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Shih HJ, Cheng SC, Shih PJ. Experimental evaluation of corneal stress-optic coefficients using a pair of force test. J Mech Behav Biomed Mater 2024; 152:106454. [PMID: 38354567 DOI: 10.1016/j.jmbbm.2024.106454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 01/04/2024] [Accepted: 01/31/2024] [Indexed: 02/16/2024]
Abstract
BACKGROUND Topography and tomography are valuable techniques for measuring the corneal shape, but they cannot directly assess its internal mechanical stresses. And nonuniform corneal stress plays a crucial biomechanical role in the progression of diseases and postoperative changes. Given the cornea's inherent transparency, analyzing corneal stresses using the photoelasticity method is highly advantageous. However, quantification of photoelasticity faces challenges in obtaining the stress-optic coefficient due to wrinkles caused by the non-spherical geometry during tensional experiments. OBJECTIVE In this study, we propose an innovative experimental setup aimed at generating a gradient field of simple shear stress and achieving surface flatness during corneal stretching experiments, enabling the acquisition of the stress-optic coefficient through comparison with numerical results. METHODS Our designed setup applies fluid pressure and force couples on the cornea. The internal fluid pressure maintains the corneal shape, preventing wrinkles, while the force couples create a stress field leading to isochromatic fringes. RESULTS We successfully measured the stress-optic coefficients of the porcine anisotropic cornea in ex-vivo as 1.87 × 10-9 (horizontal) and 1.97 × 10-9 (vertical) (m2/N). Each isochromatic fringe order represents a shear stress range of 6.05 × 104 Pa under a low tension. CONCLUSIONS This study establishes a significant connection between corneal photoelastic patterns and the quantification of corneal stress by enabling direct measurement through advanced photoelastic visualization technology for clinical applications.
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Affiliation(s)
- Hua-Ju Shih
- Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan
| | - Shan-Chien Cheng
- Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei, Taiwan.
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2
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Tseng WH, Chiu HL, Hsiao TY, Yang TL, Shih PJ. Identification and analysis of Nonlinear behaviors of vocal fold biomechanics during phonation to assess efficacy of surgery for benign laryngeal Diseases. Comput Biol Med 2024; 169:107946. [PMID: 38176211 DOI: 10.1016/j.compbiomed.2024.107946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 12/21/2023] [Accepted: 01/01/2024] [Indexed: 01/06/2024]
Abstract
BACKGROUND Current voice assessments focus on perceptive evaluation and acoustic analysis. The interaction of vocal tract pressure (PVT) and vocal fold (VF) vibrations are important for volume and pitch control. However, there are currently little non-invasive ways to measure PVT. Limited information has been provided by previous human trials, and interactions between PVT and VF vibrations and the potential clinical application remain unclear. Here, we propose a non-invasive method for monitoring the nonlinear characteristics of PVT and VF vibrations, analyze voices from pathological and healthy individuals, and evaluate treatment efficacy. METHOD Healthy volunteers and patients with benign laryngeal lesions were recruited for this study. PVT was estimated using an airflow interruption method, VF vibrational frequency was calculated from accelerometer signals, and nonlinear relationships between PVT and VF vibrations were analyzed. Results from healthy volunteers and patients, as well as pre- and post-operation for the patients, were compared. RESULTS For healthy volunteers, nonlinearity was exhibited as an initial increase and then prompt decrease in vibrational frequency at the end of phonation, coinciding with PVT equilibrating with the subglottal pressure upon airflow interruption. For patients, nonlinearity was present throughout the phonation period pre-operatively, but showed a similar trend to healthy volunteers post-operatively. CONCLUSION This novel method simultaneously monitors PVT and VF vibration and helps clarify the role of PVT. The results demonstrate differences in nonlinear characteristics between healthy volunteers and patients, and pre-/post-operation in patients. The method may serve as an analysis tool for clinicians to assess pathological phonation and treatment efficacy.
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Affiliation(s)
- Wen-Hsuan Tseng
- Department of Otolaryngology, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan; Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Hsiang-Ling Chiu
- Department of Otolaryngology, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Tzu-Yu Hsiao
- Department of Otolaryngology, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
| | - Tsung-Lin Yang
- Department of Otolaryngology, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan; Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan; Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei, Taiwan.
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Shih PJ, Shih HJ, Wang IJ, Chang SW. The extraction and application of antisymmetric characteristics of the cornea during air-puff perturbations. Comput Biol Med 2024; 168:107804. [PMID: 38070205 DOI: 10.1016/j.compbiomed.2023.107804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 11/04/2023] [Accepted: 11/29/2023] [Indexed: 01/10/2024]
Abstract
BACKGROUND A non-contact tonometer is used to measure intraocular pressure, and studies have primarily relied on apex displacements to assess corneal properties. However, previous studies have overlooked the asymmetric characteristics of lateral corneal perturbations, leading to a gap in understanding of the lateral mechanical properties and its application. METHOD To investigate these lateral perturbations, we designed an experiment to sequentially record the corneal profiles when two consecutive air-puffs were applied at the center of the same cornea within a short period. Moreover, we used modal decomposition to decompose anterior surface profiles into symmetric and antisymmetric modes to comprehensively analyze the asymmetric characteristics. To extract mechanical properties, we utilized high-pass frequency analysis (>250 Hz) to filter out noise and errors. RESULTS Symmetric modes between the two consecutive air-puffs exhibited major similarities during vibration; however, antisymmetric modes exhibited minor differences in lateral perturbations of asymmetric vibration. The antisymmetric modes might be related to air-puff misalignment and mechanical properties. Through applying frequency analysis, the mechanical properties could be proven at high frequencies and misalignment shown at low frequencies. Furthermore, we compared the corneal vibration profiles of 259 healthy participants and 50 patients with keratoconus. Their properties showed that the antisymmetric modes of the keratoconus group exhibited a completely opposite direction of deformation compared to that in the healthy group. CONCLUSIONS Our proposed algorithm not only extracts antisymmetric characteristics but also offers valuable insights into decompose misalignment and mechanical properties of healthy and keratoconus corneas, presenting a new perspective for corneal biomechanics.
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Affiliation(s)
- Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei, Taiwan.
| | - Hua-Ju Shih
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - I-Jong Wang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
| | - Shu-Wen Chang
- Department of Ophthalmology, Far Eastern Memorial Hospital, New Taipei City, Taiwan.
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Kuo YC, Cheng CY, Chen LC, Lawal B, Shih PJ, Huang HS. Diagnosis of kidney insufficiency by using the pressure waveforms of wrist-type sphygmomanometers: toward a convenient point-of-care device. Am J Transl Res 2023; 15:6015-6025. [PMID: 37969185 PMCID: PMC10641355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 09/26/2023] [Indexed: 11/17/2023]
Abstract
OBJECTIVES Digital sphygmomanometers have been used for more than 40 years in Western medicine for accurately measuring systolic and diastolic blood pressures, which are vital signs observed for the diagnosis of different diseases. Similarly, traditional Chinese medicine (TCM) has been using wrist pulse diagnosis for thousands of years. Some studies have combined digital wrist pulse signals and the diagnosis method of TCM to quantify pulse waves and identify diseases. However, the effectiveness of this approach is limited because of scattered methods and complex pathological features. Moreover, the literature on TCM does not provide quantitative data or objective indicators. METHODS In this prospective study, we developed a diagnostic system that contains a modified sphygmomanometer. In addition, we designed a procedure for analyzing pulse waves with 156 features of harmonic modes and a decision tree method for diagnosing kidney insufficiency. RESULTS In the decision tree method, at least three features of harmonic modes can achieve an accuracy of 0.86, a specificity of 0.91, and a Cohen's kappa coefficient of 0.72. By comparison, the random forest method can achieve an accuracy of 0.99, a specificity of 0.99, and a Cohen's kappa coefficient of 0.94 within 200 trees. The results of this study indicated that even in patients with kidney insufficiency and complex etiology, common features can be distinguished by identifying changes in pulse waveforms. CONCLUSION By using the modified sphygmomanometer to measure blood pressure, people can monitor their health status and take care of it in advance by simply measuring their blood pressure.
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Affiliation(s)
- Yu-Cheng Kuo
- Department of Pharmacology, School of Medicine, College of Medicine, Taipei Medical UniversityTaipei 11031, Taiwan
- School of Post-Baccalaureate Chinese Medicine, College of Chinese Medicine, China Medical UniversityTaichung 40604, Taiwan
| | - Chung-Yi Cheng
- Division of Nephrology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical UniversityTaipei 11031, Taiwan
- Division of Nephrology, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical UniversityTaipei 11031, Taiwan
- Research Center of Urology and Kidney, School of Medicine, College of Medicine, Taipei Medical UniversityTaipei 11031, Taiwan
| | - Lung-Ching Chen
- Division of Cardiology, Department of Internal Medicine, Shin Kong Wu Ho-Su Memorial HospitalTaipei 11101, Taiwan
- School of Medicine, Fu Jen Catholic UniversityNew Taipei 24205, Taiwan
| | - Bashir Lawal
- Graduate Institute for Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical UniversityTaipei 11031, Taiwan
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan UniversityTaipei 10617, Taiwan
| | - Hsu-Shan Huang
- Graduate Institute for Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical UniversityTaipei 11031, Taiwan
- Graduate Institute of Medical Sciences, National Defense Medical CentreTaipei 114, Taiwan
- Ph.D. Program in Biotechnology Research and Development, College of Pharmacy, Taipei Medical UniversityTaipei 11031, Taiwan
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Chen YC, Kuo KN, Takagi T, Takayama S, Shih PJ, Chang CH. A new technique for separating radioulnar synostosis with vascularized flap: a case report. JSES Int 2023; 7:709-713. [PMID: 37426932 PMCID: PMC10328788 DOI: 10.1016/j.jseint.2023.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2023] Open
Affiliation(s)
- Yi-Chih Chen
- Department of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
- Department of Orthopaedics, Cathay General Hospital, Taipei, Taiwan
| | - Ken N. Kuo
- Department of Orthopaedic Surgery, National Taiwan University Hospital, Taipei, Taiwan
- Cochrane Taiwan, Taipei Medical University, Taipei, Taiwan
| | - Takehiko Takagi
- Division of Orthopaedic Surgery, Department of Surgical Specialties, National Center for Child Health and Development, Setagaya-Ku, Tokyo, Japan
| | - Shinichiro Takayama
- Division of Orthopaedic Surgery, Department of Surgical Specialties, National Center for Child Health and Development, Setagaya-Ku, Tokyo, Japan
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
| | - Chia-Hsieh Chang
- Department of Pediatric Orthopaedics, Chang Gung Memorial Hospital, Taoyuan, Taiwan
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Hsu FLT, Shih PJ, Wang IJ. Development and validation of an intuitive biomechanics-based method for intraocular pressure measurement: a modal analysis approach. BMC Ophthalmol 2023; 23:124. [PMID: 36973657 PMCID: PMC10041475 DOI: 10.1186/s12886-023-02867-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 03/20/2023] [Indexed: 03/29/2023] Open
Abstract
BACKGROUND Current intraocular pressure (IOP) measurements based on non-contact tonometry are derived from statistics-driven equations and lack biomechanical significance, which often leads to under-estimation in post-refractive surgery cornea. This study aims to introduce and validate modal analysis-derived intraocular pressure (mIOP) as a novel method generated through Legendre-based modal decomposition of the anterior corneal contour; it provides an accurate and intuitive IOP measurement from an energy-based perspective. METHODS This retrospective study included 680 patients. Healthy participants were divided into reference (n = 385) and validation (n = 142) datasets, and the others underwent either femtosecond-assisted laser in situ keratomileusis (FS-LASIK, n = 58) or transepithelial photorefractive keratectomy (TPRK, n = 55). Corneal curvature of the right eyes was extracted from raw serial cross-sectional images of the cornea generated by Corvis ST, a noncontact tonometer with a high-speed Scheimpflug-camera. Legendre expansion was then applied to the corneal curvature to obtain the modal profiles (i.e., temporal changes of the coefficient for each basis polynomial [modes]). Using the reference dataset, feature selection on the modal profiles generated a final mIOP model consisting of a single parameter: total area under curve (frames 1-140) divided by the area under curve of the rising phase (frames 24-40) in the fourth mode, i.e. the M4 ratio. Validation was performed in both the healthy validation and postoperative datasets. IOP-Corvis, pachymetry-corrected IOP, biomechanically corrected IOP, and mIOP values were compared. For the FS-LASIK and TPRK groups, pairwise postoperative IOP changes were analyzed through repeated measures analysis of variance, and agreement was examined through Bland-Altman analysis. Using a finite element analysis based three-dimensional model of the human cornea, we further compared the M4 ratio with the true intraocular pressure within the physiological range. RESULTS The M4 ratio-based mIOP demonstrated weak to negligible association with age, radius of corneal curvature, and central corneal thickness (CCT) in all validation analyses, and performed comparably with biomechanically corrected IOP (bIOP) in the refractive surgery groups. Both remained nearly constant postoperatively and were not influenced by CCT changes. Additionally, M4 ratio accurately represented true intraocular pressure in the in silico model. CONCLUSIONS mIOP is a reliable IOP measurement in healthy and postrefractive surgery populations. This energy-based, ratio-derived approach effectively filters out pathological, rotational, misaligned movements and serves as an interpatient self-calibration index. Modal analysis of corneal deformation dynamics provides novel insights into regional corneal responses against pressure loading.
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Affiliation(s)
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, 10048, Taipei, Taiwan.
| | - I-Jong Wang
- College of Medicine, National Taiwan University, 10048, Taipei, Taiwan
- Department of Ophthalmology, National Taiwan University Hospital, 10048, Taipei, Taiwan
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Chou CC, Shih PJ, Jou TS, Hsu MY, Chen JP, Hsu RH, Lee NC, Chien YH, Hwu WL, Wang IJ. Corneal Biomechanical Characteristics in Osteogenesis Imperfecta With Collagen Defect. Transl Vis Sci Technol 2023; 12:14. [PMID: 36622688 PMCID: PMC9838590 DOI: 10.1167/tvst.12.1.14] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Purpose To identify the characteristic corneal biomechanical properties of osteogenesis imperfecta (OI), and to compare the corneal biomechanical properties between OI and keratoconus. Methods We included 46 eyes of 23 patients with OI, 188 eyes of 99 keratoconus patients, and 174 eyes of 92 normal controls to compare corneal biomechanical parameters between OI corneas, keratoconus, and normal controls by using Corneal Visualization Scheimpflug Technology (Corvis ST). Results Patients with OI had significantly higher Corvis biomechanical index (CBI) (P < 0.001), higher tomographic and biomechanical index (TBI) (P = 0.040), lower Corvis Biomechanical Factor (CBiF) (P = 0.034), and lower stiffness parameter at first applanation (SP-A1) (P < 0.001) compared with normal controls. In contrast, OI group showed lower CBI (P < 0.001), lower TBI (P < 0.001), higher CBiF (P < 0.001), and higher SP-A1 (P = 0.020) than keratoconus group. Notably, the stress-strain index (SSI) was not significantly different between the OI and normal controls (P = 1.000), whereas keratoconus showed the lowest SSI compared with OI group (P = 0.025) and normal controls (P < 0.001). Conclusions Although the corneal structures of OI patients are less stable and easier to deform as compared to those of the control group, there is no significant difference in material stiffness observed between the OI and normal controls. In contrast, the corneas of keratoconus showed not only lower structural stability and higher deformability but also lower material stiffness compared with those of OI cornea and normal controls. Translational Relevance The biomechanical alterations are different between OI corneas and keratoconus.
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Affiliation(s)
- Chien-Chih Chou
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan,School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan,Department of Ophthalmology, Taichung Veterans General Hospital, Taichung, Taiwan,Department of Post-Baccalaureate Medicine, College of Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
| | - Tzuu-Shuh Jou
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan,Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Min-Yen Hsu
- School of Medicine, Chung Shan Medical University, Taichung, Taiwan,Department of Ophthalmology, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Jun-Peng Chen
- Biostatistics Task Force of Taichung Veterans General Hospital, Taichung, Taiwan
| | - Rai-Hseng Hsu
- Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan,Department of Pediatrics, National Taiwan University Hospital, Taipei, Taiwan
| | - Ni-Chung Lee
- Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan,Department of Pediatrics, National Taiwan University Hospital, Taipei, Taiwan
| | - Yin-Hsiu Chien
- Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan,Department of Pediatrics, National Taiwan University Hospital, Taipei, Taiwan
| | - Wuh-Liang Hwu
- Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan,Department of Pediatrics, National Taiwan University Hospital, Taipei, Taiwan
| | - I-Jong Wang
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan,Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan,Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
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Chou CC, Shih PJ, Wang CY, Jou TS, Chen JP, Wang IJ. Corvis Biomechanical Factor Facilitates the Detection of Primary Angle Closure Glaucoma. Transl Vis Sci Technol 2022; 11:7. [PMID: 36180025 PMCID: PMC9547358 DOI: 10.1167/tvst.11.10.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To characterize the corneal biomechanical properties of primary angle closure glaucoma (PACG) and to investigate the diagnostic performance of combining corneal biomechanical parameters and anterior segment parameters in detecting PACG. Methods This retrospective cross-sectional study evaluated 79 and 81 eyes of normal controls and patients with PACG, respectively. Corvis Biomechanical Factor (CBiF) and anterior chamber volume (ACV) were measured using the Corvis ST and Pentacam, respectively. We performed multivariable logistic regression, adjusted for age, sex, central corneal thickness, intraocular pressure, and ACV to evaluate the effect of CBiF on PACG. The area under the receiver operating curve (AUC) was calculated to compare the diagnostic performance of ACV, CBiF, and ACV-CBiF combination for detecting PACG. Results The median CBiF of the control and PACG groups was 6.61 (interquartile range [IQR], 6.39–6.88) and 6.20 (IQR, 5.93–6.48), respectively (P < 0.001). A lower CBiF, suggestive of decreased corneal biomechanical stability, increased the odds of PACG (odds ratio, 0.029; 95% confidence interval [CI], 0.003–0.266; P = 0.002) in the multivariable logistic regression model. The ACV–CBiF combination yielded the highest AUC (0.934; 95% CI, 0.882–0.968) compared with ACV alone (0.878; 95% CI, 0.823–0.928). The ACV-CBiF combination had significantly higher discriminatory ability than that of ACV alone (DeLong test, P = 0.004). Conclusions Lower CBiF and ACV may act as independent predictors for PACG. Combining ACV and CBiF may enhance detection of PACG. Translational Relevance The combination of corneal biomechanical parameters and anterior segment parameters enhances the detection of PACG.
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Affiliation(s)
- Chien-Chih Chou
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.,Department of Ophthalmology, Taichung Veterans General Hospital, Taichung, Taiwan.,School of Medicine, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Department of Post-Baccalaureate Medicine, College of Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
| | - Chun-Yuan Wang
- Department of Ophthalmology, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Tzuu-Shuh Jou
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.,Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jun-Peng Chen
- Biostatistics Task Force of Taichung Veterans General Hospital, Taichung, Taiwan
| | - I-Jong Wang
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.,Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
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Tai HY, Lin JJ, Huang YH, Shih PJ, Wang IJ, Yen JY. Correlation between corneal dynamic responses and keratoconus topographic parameters. J Int Med Res 2022; 50:3000605221108100. [PMID: 35766023 PMCID: PMC9247384 DOI: 10.1177/03000605221108100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Objective To investigate the correlation between corneal biomechanical properties and
topographic parameters using machine learning networks for automatic
severity diagnosis and reference benchmark construction. Methods This was a retrospective study involving 31 eyes from 31 patients with
keratonus. Two clustering approaches were used (i.e., shape-based and
feature-based). The shape-based method used a keratoconus benchmark
validated for indicating the severity of keratoconus. The feature-based
method extracted imperative features for clustering analysis. Results There were strong correlations between the symmetric modes and the
keratoconus severity and between the asymmetric modes and the location of
the weak centroid. The Pearson product-moment correlation coefficient (PPMC)
between the symmetric mode and normality was 0.92 and between the asymmetric
mode and the weak centroid value was 0.75. Conclusion This study confirmed that there is a relationship between the keratoconus
signs obtained from topography and the corneal dynamic behaviour captured by
the Corvis ST device. Further studies are required to gather more patient
data to establish a more extensive database for validation.
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Affiliation(s)
- Hsi-Yun Tai
- Department of Mechanical Engineering, National Taiwan University, Taipei
| | - Jun-Ji Lin
- Department of Mechanical Engineering, National Taiwan University, Taipei
| | - Yi-Hung Huang
- Department of Mechanical Engineering, National Taiwan University, Taipei
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei
| | - I-Jong Wang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei
| | - Jia-Yush Yen
- Department of Mechanical Engineering, National Taiwan University, Taipei
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Shih PJ, Wu SJ, Sung YH, Tung YT, Chang CY, Hatamie S, Dai ZX. Eye orbit effects on eyeball resonant frequencies and acoustic tonometer measurements. Sci Rep 2022; 12:4883. [PMID: 35318400 PMCID: PMC8941096 DOI: 10.1038/s41598-022-08874-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 03/14/2022] [Indexed: 11/11/2022] Open
Abstract
The eye orbit has mechanical and acoustic characteristics that determine resonant frequencies and amplify acoustic signals in certain frequency ranges. These characteristics also interfere with the acoustic amplitudes and frequencies of eyeball when measured with an acoustic tonometer. A model in which a porcine eyeball was embedded in ultrasonic conductive gel in the orbit of a model skull was used to simulate an in vivo environment, and the acoustic responses of eyeballs were detected. The triggering source was a low-power acoustic speaker contacting the occipital bone, and the detector was a high-resolution microphone with a dish detecting the acoustic signals without contacting the cornea. Dozens of ex vivo porcine eyeballs were tested at various intraocular pressure levels to detect their resonant frequencies and acoustic amplitudes in their power spectra. We confirmed that the eyeballs’ resonant frequencies were proportional to intraocular pressure, but interference from orbit effects decreased the amplitudes in these resonant frequency ranges. However, we observed that the frequency amplitudes of eyeballs were correlated with intraocular pressure in other frequency ranges. We investigated eye orbit effects and demonstrated how they interfere with the eyeball’s resonant frequencies and frequency amplitudes. These results are useful for developing advanced acoustic tonometer.
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Affiliation(s)
- Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei, 10617, Taiwan, ROC.
| | - Shao-Jie Wu
- Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan, ROC
| | - Ya-Hsing Sung
- Department of Biomedical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei, 10617, Taiwan, ROC
| | - Yu-Ting Tung
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan, ROC
| | - Chia-Yu Chang
- Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan, ROC
| | - Shadie Hatamie
- Department of Biomedical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei, 10617, Taiwan, ROC
| | - Zhi-Xuan Dai
- Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan, ROC
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Chang CY, Dai ZX, Shih PJ. Modeling and simulation of cell migration on the basis of force equilibrium. Int J Numer Method Biomed Eng 2022; 38:e3550. [PMID: 34719116 DOI: 10.1002/cnm.3550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 10/26/2021] [Indexed: 06/13/2023]
Abstract
To study cell behavior, we developed a cell model to simulate cell movements and the interacting forces among cells and between cells and obstacles. The developed model simulates several cells simultaneously and examines correlations among characteristic parameters between cells and substrates during migration. We modified Odde's model to develop fundamental model, applied Gillespie's stochastic algorithm to design time during in the migration simulation, and employed Keren's membrane theory to analyze the equilibrium at the leading edges. Thus, the proposed model can analyze stresses due to substrate, the intracellular body, and the external interaction between cells and obstacles. Simulation results indicate that cell-cell interaction depends on the equilibrium between the forces at the leading edge of the membrane, namely the cell-substrate interaction force, cell-cell interaction forces, and the cell membrane force. These results also indicate that the migration direction is dependent on the resultant forces. The membrane force and substrate force directions are "low correlation," and the polymerization rate exhibits "little correlative" with the migration direction. We propose a modified cell migration model for simulating allocation and interaction among multiple cells. This model helps indicate the weightings of characteristic parameters that affect the cell migration direction and velocity.
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Affiliation(s)
- Chia-Yu Chang
- Department of Mechanical Engineering, National Taiwan University, Taipei city, Taiwan
| | - Zhi-Xuan Dai
- Department of Mechanical Engineering, National Taiwan University, Taipei city, Taiwan
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei city, Taiwan
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12
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Wu CH, Shih PJ, Tsai YC, Dai CL. Manufacturing and Characterization of Three-Axis Magnetic Sensors Using the Standard 180 nm CMOS Technology. Sensors (Basel) 2021; 21:s21216953. [PMID: 34770260 PMCID: PMC8587165 DOI: 10.3390/s21216953] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 10/14/2021] [Accepted: 10/18/2021] [Indexed: 12/04/2022]
Abstract
A three-axis micro magnetic sensor (MS) is developed based on the standard 180 nm complementary metal oxide semiconductor (CMOS) technology. The MS designs two magnetic sensing elements (MSEs), which consists of an x/y-MSE and an z-MSE, to reduce cross-sensitivity. The x/y-MSE is constructed by an x-MSE and an y-MSE that are respectively employed to detect in the x- and y-direction magnetic field (MF). The z-MSE is used to sense in the z-direction MF. The x/y-MSE, which is constructed by two magnetotransistors, designs four additional collectors that are employed to increase the sensing current and to enhance the sensitivity of the MS. The Sentaurus TCAD software simulates the characteristic of the MS. The measured results reveal that the MS sensitivity is 534 mV/T in the x-direction MF, 525 mV/T in the y-direction MF and 119 mV/T in the z-axis MF.
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Affiliation(s)
- Chi-Han Wu
- Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan;
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei 106, Taiwan;
| | - Yao-Chuan Tsai
- Department of Bio-Industrial Mechatronics Engineering, National Chung Hsing University, Taichung 402, Taiwan;
| | - Ching-Liang Dai
- Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan;
- Correspondence: ; Tel.: +886-4-2284-0433; Fax: +886-4-2287-7170
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13
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Hatamie S, Shih PJ, Chen BW, Shih HJ, Wang IJ, Young TH, Yao DJ. Effects of Electromagnets on Bovine Corneal Endothelial Cells Treated with Dendrimer Functionalized Magnetic Nanoparticles. Polymers (Basel) 2021; 13:3306. [PMID: 34641122 PMCID: PMC8512180 DOI: 10.3390/polym13193306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 09/23/2021] [Accepted: 09/24/2021] [Indexed: 11/17/2022] Open
Abstract
To improve bovine corneal endothelial cell (BCEC) migration, enhance cell energy, and facilitate symmetric cell distribution in corneal surfaces, an electromagnet device was fabricated. Twenty nanometer superparamagnetic iron oxide nanoparticles (SPIONs) functionalized with fourth-generation dendrimer macromolecules were synthesized, and their size and structure were evaluated using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The results confirmed the configuration of the dendrimer on the SPION surfaces. In vitro biocompatibility was assessed using the 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyl tetrazolium bromide assay. No significant toxicity was noted on BCECs within 24 h of incubation. In the cell migration assay, cells treated with dendrimer-coated SPIONs exhibited a relatively high wound healing rate under sample addition (1 μg/mL) under a magnetic field. Real-time PCR on BCECs treated with dendrimer-coated SPIONs revealed upregulation of specific genes, including AT1P1 and NCAM1, for BCECs-dendrimer-coated SPIONs under a magnetic field. The three-dimensional dispersion of BCECs containing dendrimer-coated SPIONs under a magnetic field was evaluated using COMSOL Multiphysics software. The results revealed the BCECs-SPION vortex pattern layers in the corneal surface corresponded to the electromagnet's displacement from the ocular surface. Magnetic resonance imaging (MRI) indicated that dendrimer-coated SPIONs can be used as a T2 contrast agent.
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Affiliation(s)
- Shadie Hatamie
- College of Medicine, National Taiwan University, Taipei 10048, Taiwan;
- Department of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan;
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan;
| | - Bo-Wei Chen
- Institute of Nanoengineering and Microsystem, National Tsing Hua University, Hsinchu 30013, Taiwan; (B.-W.C.); (D.-J.Y.)
| | - Hua-Ju Shih
- Institute of Applied Mechanics, National Taiwan University, Taipei 10617, Taiwan;
| | - I-Jong Wang
- College of Medicine, National Taiwan University, Taipei 10048, Taiwan;
| | - Tai-Horng Young
- Department of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan;
| | - Da-Jeng Yao
- Institute of Nanoengineering and Microsystem, National Tsing Hua University, Hsinchu 30013, Taiwan; (B.-W.C.); (D.-J.Y.)
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14
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Dai ZX, Shih PJ, Yen JY, Wang IJ. Functional assistance for stress distribution in cell culture membrane under periodically stretching. J Biomech 2021; 125:110564. [PMID: 34237658 DOI: 10.1016/j.jbiomech.2021.110564] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 05/28/2021] [Accepted: 05/31/2021] [Indexed: 11/19/2022]
Abstract
Dynamic cell cultures simulate the in vivo cell environment for a regular loading system with curtain strains. However, it is difficult to obtain strains that are suitable for cells without conducting multiple trials. This study develops a device that increases the strain gradient by changing the tensile section, in order to determine the effect of various cyclic strains on cultured human keratinocytes (HK) cells. This device is used to determine the effect of 3% and 5% cyclic strain and shear strain on cell proliferation and arrangement at 1 Hz. The results show that compared with static and 3% strain, a 5% cyclic strain better inhibits the proliferation of HK cells. Compared to the initial cell attachment when there is no specific directionality, the cells are aligned in the vertical stretching direction after cyclic stretching. This equipment increases the efficiency of the experiment and more intuitively maps the cell behavior and shape to the strain field and the response to the shear strain.
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Affiliation(s)
- Zhi-Xuan Dai
- Department of Mechanical Engineering, National Taiwan University, 10617 Taipei, Taiwan
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, 10617 Taipei, Taiwan.
| | - Jia-Yush Yen
- Department of Mechanical Engineering, National Taiwan University, 10617 Taipei, Taiwan; Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan
| | - I-Jong Wang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
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15
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Chou CC, Shih PJ, Lin HC, Chen JP, Yen JY, Wang IJ. Changes in Intraocular Pressure after Transepithelial Photorefractive Keratectomy and Femtosecond Laser In Situ Keratomileusis. J Ophthalmol 2021; 2021:5592195. [PMID: 33777445 PMCID: PMC7972855 DOI: 10.1155/2021/5592195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 02/22/2021] [Accepted: 02/28/2021] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the changes in intraocular pressure (IOP) and biomechanically corrected IOP (bIOP) in patients undergoing transepithelial photorefractive keratectomy (TPRK) and femtosecond laser in situ keratomileusis (FS-LASIK) and to determine the effects of preoperative biomechanical factors on IOP and bIOP changes after FS-LASIK and TPRK. DESIGN A retrospective comparative study. METHODS We retrospectively investigated the IOP and corneal biomechanical changes in 93 eyes undergoing FS-LASIK and 104 eyes undergoing TPRK in a clinical setting. Preoperative and postoperative data on ophthalmic and Corvis ST examinations, in vivo Young's modulus, and noncontact tonometry were analyzed. Marginal linear regression models with generalized estimating equations were used for intragroup and intergroup comparisons of IOP and bIOP changes. RESULTS In the univariate model, IOP reduction after FS-LASIK was 2.49 mmHg higher than that after TPRK. In addition, bIOP reduction after FS-LASIK was 1.85 mmHg higher than that after TPRK. In the multiple regression model, we revealed that IOP reduction after FS-LASIK was 1.75 mmHg higher than that after TPRK. Additionally, bIOP reduction after FS-LASIK was 1.64 mmHg higher than that after TPRK. Postoperative changes in bIOP were less than those in IOP. In addition, Young's modulus and CBI had no significant effect on postoperative IOP and bIOP changes. We establish a biomechanically predictive model using the available data to predict postoperative IOP and bIOP changes after TPRK and FS-LASIK. CONCLUSIONS Reductions in IOP and bIOP after FS-LASIK were 1.75 mmHg and 1.64 mmHg, respectively, more than those after TPRK, after adjustment for confounders. We revealed that the type of refractive surgery and peak distance (PD) were significant predictors of postoperative IOP and bIOP changes. By contrast, depth of ablation showed a significant effect on only IOP changes.
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Affiliation(s)
- Chien-Chih Chou
- Department of Ophthalmology, Taichung Veterans General Hospital, Taichung, Taiwan
- Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
| | - Hung-Chou Lin
- Dr. Lin's Eye Clinic and Laser Vision Correction Center, Taoyuan, Taiwan
| | - Jun-Peng Chen
- Biostatistics Task Force of Taichung Veterans General Hospital, Taichung, Taiwan
| | - Jia-Yush Yen
- Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan
| | - I-Jong Wang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
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16
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Hatamie S, Shih PJ, Chen BW, Wang IJ, Young TH, Yao DJ. Synergic Effect of Novel WS 2 Carriers Holding Spherical Cobalt Ferrite @cubic Fe 3O 4 (WS 2/s-CoFe 2O 4@c-Fe 3O 4) Nanocomposites in Magnetic Resonance Imaging and Photothermal Therapy for Ocular Treatments and Investigation of Corneal Endothelial Cell Migration. Nanomaterials (Basel) 2020; 10:E2555. [PMID: 33352770 PMCID: PMC7766809 DOI: 10.3390/nano10122555] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/14/2020] [Accepted: 12/16/2020] [Indexed: 12/18/2022]
Abstract
The design of novel materials to use simultaneously in an ocular system for driven therapeutics and wound healing is still challenging. Here, we produced nanocomposites of tungsten disulfide carriers with spherical cobalt ferrite nanoparticles (NPs) as core inside a cubic iron oxide NPs shell (WS2/s-CoFe2O4@c-Fe3O4). Transmission electron microscopy (TEM) confirmed that 10 nm s-CoFe2O4@c-Fe3O4 NPs were attached on the WS2 sheet surfaces. The cytotoxicity of the WS2 sheets and nanocomposites were evaluated on bovine cornea endothelial cells (BCECs) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for a duration of three days. The MTT assay results showed low toxicity of the WS2 sheets on BCECs by 67% cell viability at 100 μg/mL in 24 h, while the nanocomposites show 50% cell viability in the same conditions. The magnetic resonance imaging (MRI) of nanocomposites revealed the excellent T2-weighted imaging with an r2 contrast of 108 mM-1 S-1. The in vitro photothermal therapy based on WS2 sheets and WS2/s-CoFe2O4 @c-Fe3O4 nanocomposites using 808 nm laser showed that the maximum thermal energy dispatched in medium at different applied power densities (1200 mw, 1800, 2200, 2600 mW) was for 0.1 mg/mL of the sample solution. The migration assay of BCECs showed that the wound healing was approximately 20% slower for the cell exposed by nanocomposites compared with the control (no exposed BCECs). We believe that WS2/s-CoFe2O4@c-Fe3O4 nanocomposites have a synergic effect as photothermal therapy agents for eye diseases and could be a target in an ocular system using MRI.
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Affiliation(s)
- Shadie Hatamie
- College of Medicine, National Taiwan University, Taipei 10048, Taiwan;
- Department of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan;
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan;
| | - Bo-Wei Chen
- Institute of Nanoengineering and Microsystem, National Tsing Hua University, Hsinchu 30013, Taiwan; (B.-W.C.); (D.-J.Y.)
| | - I-Jong Wang
- College of Medicine, National Taiwan University, Taipei 10048, Taiwan;
| | - Tai-Horng Young
- Department of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan;
| | - Da-Jeng Yao
- Institute of Nanoengineering and Microsystem, National Tsing Hua University, Hsinchu 30013, Taiwan; (B.-W.C.); (D.-J.Y.)
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17
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Chen WR, Tsai YC, Shih PJ, Hsu CC, Dai CL. Magnetic Micro Sensors with Two Magnetic Field Effect Transistors Fabricated Using the Commercial Complementary Metal Oxide Semiconductor Process. Sensors (Basel) 2020; 20:s20174731. [PMID: 32825769 PMCID: PMC7506958 DOI: 10.3390/s20174731] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/09/2020] [Accepted: 08/19/2020] [Indexed: 06/01/2023]
Abstract
The fabrication and characterization of a magnetic micro sensor (MMS) with two magnetic field effect transistors (MAGFETs) based on the commercial complementary metal oxide semiconductor (CMOS) process are investigated. The magnetic micro sensor is a three-axis sensing type. The structure of the magnetic microsensor is composed of an x/y-MAGFET and a z-MAGFET. The x/y-MAGFET is employed to sense the magnetic field (MF) in the x- and y-axis, and the z-MAGFET is used to detect the MF in the z-axis. To increase the sensitivity of the magnetic microsensor, gates are introduced into the two MAGFETs. The sensing current of the MAGFET enhances when a bias voltage is applied to the gates. The finite element method software Sentaurus TCAD was used to analyze the MMS's performance. Experiments show that the MMS has a sensitivity of 182 mV/T in the x-axis MF and a sensitivity of 180 mV/T in the y-axis MF. The sensitivity of the MMS is 27.8 mV/T in the z-axis MF.
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Affiliation(s)
- Wei-Ren Chen
- Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan;
| | - Yao-Chuan Tsai
- Department of Bio-Industrial Mechatronics Engineering, National Chung Hsing University, Taichung 402, Taiwan;
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei 106, Taiwan;
| | - Cheng-Chih Hsu
- Department of Electro-Optical Engineering, National United University, Miaoli 360, Taiwan;
| | - Ching-Liang Dai
- Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan;
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18
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Ho WT, Chang JS, Chou SF, Hwang WL, Shih PJ, Chang SW, Yang MH, Jou TS, Wang IJ. Targeting non-muscle myosin II promotes corneal endothelial migration through regulating lamellipodial dynamics. J Mol Med (Berl) 2019; 97:1345-1357. [PMID: 31302714 DOI: 10.1007/s00109-019-01818-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 05/18/2019] [Accepted: 07/02/2019] [Indexed: 10/26/2022]
Abstract
Corneal endothelial cell (CEC) dysfunction causes corneal edema that may lead to blindness. In addition to corneal transplantation, simple descemetorhexis has been proposed to treat centrally located disease with adequate peripheral cell reserve, but promoting the centripetal migration of CECs is pivotal to this strategy. Here, we show that targeting non-muscle myosin II (NMII) activity by Y27632, a ROCK inhibitor, or blebbistatin, a selective NMII inhibitor, promotes directional migration of CECs and accelerates in vitro wound healing. The lamellipodial protrusion persistence is increased, and actin retrograde flow is decreased after NMII inhibition. Counteracting lamellipodial protrusion by actin-related protein 2/3 (ARP2/3) inhibitor abolishes this migration-promoting effect. Although both Y27632 and blebbistatin accelerate wound healing, cell junctional integrity and barrier function are better preserved after blebbistatin treatment, leading to more rapid corneal deturgescence in rabbit corneal endothelial wounding model. Our findings indicate that NMII is a promising therapeutic target in the treatment of CEC dysfunction. KEY MESSAGES: NMII inhibition promotes directional migration and wound healing of CECs in vitro. Lamellipodial protrusion persistence is increased after NMII inhibition. Selective NMII inhibitor preserves junctional integrity better than ROCK inhibitor. Selective NMII inhibitor accelerates corneal deturgescence after wounding in vivo.
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Affiliation(s)
- Wei-Ting Ho
- Department of Ophthalmology, Far Eastern Memorial Hospital, New Taipei City, Taiwan.,Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jung-Shen Chang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
| | - San-Fang Chou
- Department of Medical Research, Far Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Wei-Lun Hwang
- Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Po-Jen Shih
- Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, Taiwan
| | - Shu-Wen Chang
- Department of Ophthalmology, Far Eastern Memorial Hospital, New Taipei City, Taiwan.,College of Medicine, National Taiwan University, No. 7, Chung-Shan S. Rd., Taipei, Taiwan
| | - Muh-Hwa Yang
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Tzuu-Shuh Jou
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan. .,College of Medicine, National Taiwan University, No. 7, Chung-Shan S. Rd., Taipei, Taiwan. .,Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.
| | - I-Jong Wang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan. .,College of Medicine, National Taiwan University, No. 7, Chung-Shan S. Rd., Taipei, Taiwan.
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19
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Shih HJ, Dai CL, Shih PJ. Tip Pressure on Semicircular Specimens in Tapping Mode Atomic Force Microscopy in Viscous Fluid Environments. Sensors (Basel) 2017; 17:E2182. [PMID: 28937607 PMCID: PMC5676617 DOI: 10.3390/s17102182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 09/21/2017] [Accepted: 09/21/2017] [Indexed: 11/18/2022]
Abstract
Tapping mode (TM) atomic force microscopy (AFM) in a liquid environment is widely used to measure the contours of biological specimens. The TM triggers the AFM probe approximately at the resonant frequencies and controls the tip such that it periodically touches the specimen along the scanning path. The AFM probe and its tip produce a hydrodynamic pressure on the probe itself and press the specimen. The tip to specimen size ratio is known to affect the measurement accuracy of AFM, however, few studies have focused on the hydrodynamic pressure caused by the effects of specimen size. Such pressure affects the contour distortion of the biological specimen. In this study, a semi-analytical method is employed for a semicircular specimen to analyze the vorticity and pressure distributions for specimens of various sizes and at various tip locations. Changes in pressure distribution, fluid spin motion, and specimen deformation are identified as the tip approaches the specimen. The results indicate the following: the specimen surface experiences the highest pressure when the specimen diameter equals the tip width; the vorticity between tip and specimen is complex when the tip is close to the specimen center line; and the specimen inflates when the tip is aligned with the specimen center line.
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Affiliation(s)
- Hua-Ju Shih
- Institute of Applied Mechanics, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan.
| | - Ching-Liang Dai
- Department of Mechanical Engineering, National Chung Hsing University, No. 145, Xingda Rd. South Dist., Taichung 40227, Taiwan.
| | - Po-Jen Shih
- Department of Civil and Environmental Engineering, National University of Kaohsiung, No. 700, Kaohsiung University Rd., Nanzih District, Kaohsiung 81148, Taiwan.
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20
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Abstract
An acoustic tonometer that measures shifts in resonance frequencies associated with intraocular pressure (IOP) could provide an opportunity for a type of tonometer that can be operated at home or worn by patients. However, there is insufficient theoretical background, especially with respect to the uncertainty in operating frequency ranges and the unknown relationships between IOPs and resonance frequencies. The purpose of this paper is to develop a frequency function for application in an acoustic tonometer. A linear wave theory is used to derive an explicit frequency function, consisting of an IOP and seven other physiological parameters. In addition, impulse response experiments are performed to measure the natural frequencies of porcine eyes to validate the provided function. From a real-time detection perspective, explicitly providing a frequency function can be the best way to set up an acoustic tonometer. The theory shows that the resonance oscillation of the eyeball is mainly dominated by liquid inside the eyeball. The experimental validation demonstrates the good prediction of IOPs and resonance frequencies. The proposed explicit frequency function supports further modal analysis not only of the dynamics of eyeballs, but also of the natural frequencies, for further development of the acoustic tonometer.
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Affiliation(s)
- Po-Jen Shih
- Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, Taiwan
| | - Yi-Ren Guo
- Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, Taiwan
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21
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Shih PJ, Cao HJ, Huang CJ, Wang IJ, Shih WP, Yen JY. A corneal elastic dynamic model derived from Scheimpflug imaging technology. Ophthalmic Physiol Opt 2015; 35:663-72. [PMID: 26353939 DOI: 10.1111/opo.12240] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 07/23/2015] [Indexed: 11/29/2022]
Abstract
PURPOSE To simultaneously extract the corneal Young's modulus and the damping ratio from Scheimpflug imaging data. METHODS A spherical diaphragm model can better represent the geometry and physics of an eyeball than the popular mass-spring-damper model. This research derived the dynamic model of a water-filled spherical diaphragm based on the hydrodynamics and wave propagation theories. By applying modal analysis on the model, one can decouple the cornea vibration into individual modes and reconstruct the air puff vibration from the decoupled responses. By matching this response with the Scheimpflug imaging data from the Corvis(®) ST, it was then possible to extract multiple physiological properties as desired. RESULTS The dynamic modal analysis was employed to extract the corneal physiological properties of 25 Taiwanese normal subjects. Specifically, the corneal Young's moduli and damping ratios were estimated. In fact the model is dependent on the physiological parameters such as cornea thickness, densities, and intraocular pressure. It is thus also possible to extract these parameters through multi-goal minimisation processes. CONCLUSIONS The spherical diaphragm model was able to better describe the dynamic response of the eyeball. The model analysis also provides additional corneal physiological properties that were not available through other means.
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Affiliation(s)
- Po-Jen Shih
- Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, Taiwan
| | - Huei-Jyun Cao
- Department of Mechanic Engineering, National Taiwan University, Taipei, Taiwan
| | - Chun-Ju Huang
- Department of Mechanic Engineering, National Taiwan University, Taipei, Taiwan
| | - I-Jong Wang
- Department of Ophthalmology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wen-Pin Shih
- Department of Mechanic Engineering, National Taiwan University, Taipei, Taiwan
| | - Jia-Yush Yen
- Department of Mechanic Engineering, National Taiwan University, Taipei, Taiwan
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22
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Shih HJ, Shih PJ. Tip Effect of the Tapping Mode of Atomic Force Microscope in Viscous Fluid Environments. Sensors (Basel) 2015; 15:18381-401. [PMID: 26225979 PMCID: PMC4570326 DOI: 10.3390/s150818381] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 07/02/2015] [Accepted: 07/14/2015] [Indexed: 11/16/2022]
Abstract
Atomic force microscope with applicable types of operation in a liquid environment is widely used to scan the contours of biological specimens. The contact mode of operation allows a tip to touch a specimen directly but sometimes it damages the specimen; thus, a tapping mode of operation may replace the contact mode. The tapping mode triggers the cantilever of the microscope approximately at resonance frequencies, and so the tip periodically knocks the specimen. It is well known that the cantilever induces extra liquid pressure that leads to drift in the resonance frequency. Studies have noted that the heights of protein surfaces measured via the tapping mode of an atomic force microscope are ~25% smaller than those measured by other methods. This discrepancy may be attributable to the induced superficial hydrodynamic pressure, which is worth investigating. In this paper, we introduce a semi-analytical method to analyze the pressure distribution of various tip geometries. According to our analysis, the maximum hydrodynamic pressure on the specimen caused by a cone-shaped tip is ~0.5 Pa, which can, for example, pre-deform a cell by several nanometers in compression before the tip taps it. Moreover, the pressure calculated on the surface of the specimen is 20 times larger than the pressure without considering the tip effect; these results have not been motioned in other papers. Dominating factors, such as surface heights of protein surface, mechanical stiffness of protein increasing with loading velocity, and radius of tip affecting the local pressure of specimen, are also addressed in this study.
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Affiliation(s)
- Hua-Ju Shih
- Department of Civil and Environmental Engineering, National University of Kaohsiung, No. 700, Kaohsiung University Rd., Nanzih District, 81148 Kaohsiung, Taiwan.
| | - Po-Jen Shih
- Department of Civil and Environmental Engineering, National University of Kaohsiung, No. 700, Kaohsiung University Rd., Nanzih District, 81148 Kaohsiung, Taiwan.
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23
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Yang MZ, Dai CL, Shih PJ. An acetone microsensor with a ring oscillator circuit fabricated using the commercial 0.18 μm CMOS process. Sensors (Basel) 2014; 14:12735-47. [PMID: 25036331 PMCID: PMC4168457 DOI: 10.3390/s140712735] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 07/12/2014] [Accepted: 07/15/2014] [Indexed: 11/17/2022]
Abstract
This study investigates the fabrication and characterization of an acetone microsensor with a ring oscillator circuit using the commercial 0.18 μm complementary metal oxide semiconductor (CMOS) process. The acetone microsensor contains a sensitive material, interdigitated electrodes and a polysilicon heater. The sensitive material is α-Fe2O3 synthesized by the hydrothermal method. The sensor requires a post-process to remove the sacrificial oxide layer between the interdigitated electrodes and to coat the α-Fe2O3 on the electrodes. When the sensitive material adsorbs acetone vapor, the sensor produces a change in capacitance. The ring oscillator circuit converts the capacitance of the sensor into the oscillation frequency output. The experimental results show that the output frequency of the acetone sensor changes from 128 to 100 MHz as the acetone concentration increases 1 to 70 ppm.
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Affiliation(s)
- Ming-Zhi Yang
- Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan.
| | - Ching-Liang Dai
- Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan.
| | - Po-Jen Shih
- Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung 811, Taiwan 320, Taiwan.
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Shih PJ. Frequency function in atomic force microscopy applied to a liquid environment. Sensors (Basel) 2014; 14:9369-79. [PMID: 24865882 PMCID: PMC4118394 DOI: 10.3390/s140609369] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 05/20/2014] [Accepted: 05/20/2014] [Indexed: 11/16/2022]
Abstract
Scanning specimens in liquids using commercial atomic force microscopy (AFM) is very time-consuming due to the necessary try-and-error iteration for determining appropriate triggering frequencies and probes. In addition, the iteration easily contaminates the AFM tip and damages the samples, which consumes probes. One reason for this could be inaccuracy in the resonant frequency in the feedback system setup. This paper proposes a frequency function which varies with the tip-sample separation, and it helps to improve the frequency shift in the current feedback system of commercial AFMs. The frequency function is a closed-form equation, which allows for easy calculation, as confirmed by experimental data. It comprises three physical effects: the quasi-static equilibrium condition, the atomic forces gradient effect, and hydrodynamic load effect. While each of these has previously been developed in separate studies, this is the first time their combination has been used to represent the complete frequency phenomenon. To avoid "jump to contact" issues, experiments often use probes with relatively stiffer cantilevers, which inevitably reduce the force sensitivity in sensing low atomic forces. The proposed frequency function can also predict jump to contact behavior and, thus, the probe sensitivity could be increased and soft probes could be widely used. Additionally, various tip height behaviors coupling with the atomic forces gradient and hydrodynamic effects are discussed in the context of carbon nanotube probes.
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Affiliation(s)
- Po-Jen Shih
- Department of Civil and Environmental Engineering, National University of Kaohsiung, CEE NUK, No. 700, Kaohsiung University Rd., Nanzih District, 81148, Kaohsiung, Taiwan.
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Shih PJ. Tip-jump response of an amplitude-modulated Atomic Force Microscope. Sensors (Basel) 2012; 12:6666-84. [PMID: 22778663 PMCID: PMC3386762 DOI: 10.3390/s120506666] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 04/24/2012] [Accepted: 05/14/2012] [Indexed: 11/16/2022]
Abstract
The dynamic behaviors of an Atomic Force Microscope are of interest, and variously unpredictable phenomena are experimentally measured. In practical measurements, researchers have proposed many methods for avoiding these uncertainties. However, causes of these phenomena are still hard to demonstrate in simulation. To demonstrate these phenomena, this paper claims the tip-jump motion is a predictable process, and the jumping kinetic energy results in different nonlinear phenomena. It emphasizes the variation in the eigenvalues of an AFM with tip-sample distance. This requirement ensures the phase transformations from one associated with the oscillation mode to one associated with the tip-jump/sample-contact mode. Also, multi-modal analysis was utilized to ensure the modal transformation in varying tip-sample distances. In the presented model, oscillations with various tip-sample distances and with various excitation frequencies and amplitudes were compared. The results reveal that the tip-jump motion separates the oscillation orbit into two regions, and the jumping kinetic energy, comparing with the superficial potential energy, leads the oscillation to be bistable or intermittent. The sample-contact condition associates to bifurcation and chaos. Additionally, the jumping is a strong motion that occurs before the tip-sample contacts, and this motion signal can replace the sample-contact-signal to avoid destroying the sample.
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Affiliation(s)
- Po-Jen Shih
- Department of Civil and Environmental Engineering, National University of Kaohsiung, No. 700, Kaohsiung University Road, Nanzih District, 81148, Kaohsiung, Taiwan.
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Kao PH, Shih PJ, Dai CL, Liu MC. Fabrication and characterization of CMOS-MEMS thermoelectric micro generators. Sensors (Basel) 2010; 10:1315-25. [PMID: 22205869 PMCID: PMC3244015 DOI: 10.3390/s100201315] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2009] [Revised: 01/28/2010] [Accepted: 02/01/2010] [Indexed: 11/16/2022]
Abstract
This work presents a thermoelectric micro generator fabricated by the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and the post-CMOS process. The micro generator is composed of 24 thermocouples in series. Each thermocouple is constructed by p-type and n-type polysilicon strips. The output power of the generator depends on the temperature difference between the hot and cold parts in the thermocouples. In order to prevent heat-receiving in the cold part in the thermocouples, the cold part is covered with a silicon dioxide layer with low thermal conductivity to insulate the heat source. The hot part of the thermocouples is suspended and connected to an aluminum plate, to increases the heat-receiving area in the hot part. The generator requires a post-CMOS process to release the suspended structures. The post-CMOS process uses an anisotropic dry etching to remove the oxide sacrificial layer and an isotropic dry etching to etch the silicon substrate. Experimental results show that the micro generator has an output voltage of 67 μV at the temperature difference of 1 K.
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Affiliation(s)
- Pin-Hsu Kao
- Department of Mechanical Engineering, National Chung Hsing University, Taichung, 402, Taiwan; E-Mails: (P.-H.K.); (M.-C.L.)
| | - Po-Jen Shih
- Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, 811, Taiwan; E-Mail:
| | - Ching-Liang Dai
- Department of Mechanical Engineering, National Chung Hsing University, Taichung, 402, Taiwan; E-Mails: (P.-H.K.); (M.-C.L.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +886-4-22840433; Fax: +886-4-22877170
| | - Mao-Chen Liu
- Department of Mechanical Engineering, National Chung Hsing University, Taichung, 402, Taiwan; E-Mails: (P.-H.K.); (M.-C.L.)
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Shandilya H, Griffiths K, Flynn EK, Astatke M, Shih PJ, Lee JE, Gerard GF, Gibbs MD, Bergquist PL. Thermophilic bacterial DNA polymerases with reverse-transcriptase activity. Extremophiles 2004; 8:243-51. [PMID: 15197605 DOI: 10.1007/s00792-004-0384-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2003] [Accepted: 02/10/2004] [Indexed: 11/30/2022]
Abstract
Conserved motifs found in known bacterial polI DNA polymerase sequences were identified, and degenerate PCR primers were designed for PCR amplification of an internal portion of polI genes from all bacterial divisions. We describe here a method that has allowed the rapid identification and isolation of 13 polI genes from a diverse selection of thermophilic bacteria and report on the biochemical characteristics of nine of the purified recombinant enzymes. Several enzymes showed significant reverse-transcriptase activity in the presence of Mg2+, particularly the polymerases from Bacillus caldolyticus EA1, Caldibacillus cellovorans CompA.2, and Clostridium stercorarium.
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Affiliation(s)
- Harini Shandilya
- Invitrogen Corporation, 1600 Faraday Avenue, Carlsbad, CA 92008, USA
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28
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Lipsky NG, Drachman DB, Pestronk A, Shih PJ. Neural regulation of mRNA for the alpha-subunit of acetylcholine receptors: role of neuromuscular transmission. Exp Neurol 1989; 105:171-6. [PMID: 2546789 DOI: 10.1016/0014-4886(89)90116-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Levels of mRNA for acetylcholine receptor (AChR) subunits are relatively low in innervated skeletal muscles. Following denervation they rise rapidly, leading to increased AChR synthesis. The mechanism by which motor nerves normally regulate these mRNA levels is not yet known. In order to determine the possible role of synaptic transmission in this process, we have compared the effect of blockade of cholinergic ACh transmission with that of surgical denervation. Blockade of quantal ACh transmission was produced by injection of type A botulinum toxin into the soleus muscles of rats. We measured mRNA for the alpha-subunit of the AChR (alpha-AChR mRNA) in RNA extracts of botulinum-treated, denervated, and normal control muscles by hybridization with a highly specific cDNA probe. Our findings show that treatment with botulinum toxin resulted in an increase in alpha-AChR mRNA which was similar to the effect of surgical denervation, although slower in its time course. Since botulinum toxin specifically inhibits quantal ACh release, these results support the concept that cholinergic synaptic transmission plays a key role in mediating the neural control of the alpha-AChR message. The difference between the effects of denervation and botulinum-treatment may be explained by the fact that botulinum toxin does not block the spontaneous non-quantal component of ACh transmission, which has previously been shown to have a partial influence in regulating certain properties of muscles. The present results suggest that synaptic transmission has an important influence in regulating gene expression in the target cell.
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Affiliation(s)
- N G Lipsky
- Department of Neurology and Neurosciences, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205
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