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Kurdadze T, Lamadie F, Nehme KA, Teychené S, Biscans B, Rodriguez-Ruiz I. On-Chip Photonic Detection Techniques for Non-Invasive In Situ Characterizations at the Microfluidic Scale. SENSORS (BASEL, SWITZERLAND) 2024; 24:1529. [PMID: 38475065 DOI: 10.3390/s24051529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 02/21/2024] [Accepted: 02/22/2024] [Indexed: 03/14/2024]
Abstract
Microfluidics has emerged as a robust technology for diverse applications, ranging from bio-medical diagnostics to chemical analysis. Among the different characterization techniques that can be used to analyze samples at the microfluidic scale, the coupling of photonic detection techniques and on-chip configurations is particularly advantageous due to its non-invasive nature, which permits sensitive, real-time, high throughput, and rapid analyses, taking advantage of the microfluidic special environments and reduced sample volumes. Putting a special emphasis on integrated detection schemes, this review article explores the most relevant advances in the on-chip implementation of UV-vis, near-infrared, terahertz, and X-ray-based techniques for different characterizations, ranging from punctual spectroscopic or scattering-based measurements to different types of mapping/imaging. The principles of the techniques and their interest are discussed through their application to different systems.
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Affiliation(s)
- Tamar Kurdadze
- CEA, DES, ISEC, DMRC, Univ Montpellier, 30207 Bagnols-sur-Ceze, Marcoule, France
| | - Fabrice Lamadie
- CEA, DES, ISEC, DMRC, Univ Montpellier, 30207 Bagnols-sur-Ceze, Marcoule, France
| | - Karen A Nehme
- Laboratoire de Génie Chimique, CNRS, UMR 5503, 4 Allée Emile Monso, 31432 Toulouse, France
| | - Sébastien Teychené
- Laboratoire de Génie Chimique, CNRS, UMR 5503, 4 Allée Emile Monso, 31432 Toulouse, France
| | - Béatrice Biscans
- Laboratoire de Génie Chimique, CNRS, UMR 5503, 4 Allée Emile Monso, 31432 Toulouse, France
| | - Isaac Rodriguez-Ruiz
- Laboratoire de Génie Chimique, CNRS, UMR 5503, 4 Allée Emile Monso, 31432 Toulouse, France
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2
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Zhong Y, Yu H, Wen Y, Zhou P, Guo H, Zou W, Lv X, Liu L. Novel Optofluidic Imaging System Integrated with Tunable Microlens Arrays. ACS APPLIED MATERIALS & INTERFACES 2023; 15:11994-12004. [PMID: 36655899 DOI: 10.1021/acsami.2c20191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Optofluidic tunable microlens arrays (MLAs) can manipulate and control light propagation using fluids. Lately, their applicability to miniature lab-on-a-chip systems is being extensively researched. However, it is difficult to incorporate 3D MLAs directly in a narrow microfluidic channel using common techniques. This has resulted in limited research on variable focal length imaging with optofluidic 3D MLAs. In this paper, we propose a method for fabricating MLAs in polydimethylsiloxane (PDMS)-based microchannels via electrohydrodynamic jet (E-jet) printing to achieve optofluidic tunable MLAs. Using this method, MLAs of diameters 15 to 80 μm can be fabricated in microfluidic channels with widths of 200 and 300 μm. By alternately using solutions with different refractive indices in the microchannel, the optofluidic microlenses exhibit reversible modulation properties while retaining the morphologies and refractive indices of the microlenses. The focal length of the resulting optofluidic chip can have threefold tunability, thereby achieving an imaging depth of approximately 450 μm. This outstanding advantage is useful in observing microspheres and cells flowing in the microfluidic system. Thus, the proposed optofluidic chip exhibits great potential for cell counting and imaging applications.
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Affiliation(s)
- Ya Zhong
- State Key Laboratory of Robotics, Chinese Academy of Sciences, Shenyang Institute of Automation, Shenyang110016, China
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang110016, China
- University of Chinese Academy of Sciences, Beijing100049, China
| | - Haibo Yu
- State Key Laboratory of Robotics, Chinese Academy of Sciences, Shenyang Institute of Automation, Shenyang110016, China
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang110016, China
| | - Yangdong Wen
- Institute of Urban Rail Transportation, Southwest Jiaotong University, Chengdu610000, China
| | - Peilin Zhou
- College of Mechanical and Electrical Engineering, Henan Agricultural University, Zhengzhou450002, China
| | - Hongji Guo
- State Key Laboratory of Robotics, Chinese Academy of Sciences, Shenyang Institute of Automation, Shenyang110016, China
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang110016, China
| | - Wuhao Zou
- State Key Laboratory of Robotics, Chinese Academy of Sciences, Shenyang Institute of Automation, Shenyang110016, China
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang110016, China
- University of Chinese Academy of Sciences, Beijing100049, China
| | - Xiaofeng Lv
- State Key Laboratory of Robotics, Chinese Academy of Sciences, Shenyang Institute of Automation, Shenyang110016, China
- Northeastern University, Shenyang110016, China
| | - Lianqing Liu
- State Key Laboratory of Robotics, Chinese Academy of Sciences, Shenyang Institute of Automation, Shenyang110016, China
- Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang110016, China
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3
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Tang J, Qiu G, Cao X, deMello A, Wang J. Microfluid Switching-Induced Transient Refractive Interface. ACS Sens 2022; 7:3521-3529. [PMID: 36356161 DOI: 10.1021/acssensors.2c01901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The laminar flow interface (LFI) developed at low Reynolds numbers is one of the most prominent features of microscale flows and has been employed in a diverse range of optofluidic applications. The formation of LFIs usually requires the manipulation of multiple streams within a microchannel using a complex hydrodynamic pumping system. Herein, we present a new type of LFI that is generated by fluid switching within a three-dimensional (3D) microlens-incorporating microfluidic chip (3D-MIMC). Since Poiseuille flows exhibit a parabolic velocity profile, the LFI is cone-like in shape and acts as a transient refractive interface (TRI), which is sensitive to the refractive index (RI) and the Péclet number (Pe) of the switching fluids. In response to the TRI, the intensity of the transmitted light can be intensified or attenuated depending on the sequence of fluid switching operations. By incorporating three-dimensional (3D) microlenses and increasing the Pe values, the profile and amplitude of the intensity peak are both significantly improved. The limit of detection (LoD) for a sodium chloride (NaCl) solution at Pe = 1363 is as low as 0.001% (w/w), representing an improvement of 1-2 orders of magnitude when compared to existing optofluidic concentration sensors based on intensity modulation. Fluid switching of a variety of inorganic and organic sample fluids confirms that the specific optical response (Kor) correlates positively with both Pe and the specific RI (Knc), obeying a linear relationship. This model is further verified through cross-validations and used to estimate the molecular diffusion coefficient (D) of a range of species. Furthermore, by virtue of the TRI, we achieve a sensitive measurement of optical-equivalent total dissolved solids (OE-TDS) for environmental samples.
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Affiliation(s)
- Jiukai Tang
- Institute of Environmental Engineering, ETH Zürich, Zürich8093, Switzerland.,Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf8600, Switzerland
| | - Guangyu Qiu
- Institute of Environmental Engineering, ETH Zürich, Zürich8093, Switzerland.,Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf8600, Switzerland.,School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai200240, China
| | - Xiaobao Cao
- Institute of Chemical and Bioengineering, ETH Zürich, Zürich8093, Switzerland.,Guangzhou Lab, International Bio Island, Haizhu District, Guangzhou510005, Guangdong, China
| | - Andrew deMello
- Institute of Chemical and Bioengineering, ETH Zürich, Zürich8093, Switzerland
| | - Jing Wang
- Institute of Environmental Engineering, ETH Zürich, Zürich8093, Switzerland.,Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf8600, Switzerland
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4
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Gerald A, McCandless M, Sheth A, Aihara H, Russo S. A Soft Sensor for Bleeding Detection in Colonoscopies. ADVANCED INTELLIGENT SYSTEMS (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 4:2100254. [PMID: 35757581 PMCID: PMC9216226 DOI: 10.1002/aisy.202100254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Colonoscopies allow surgeons to detect common diseases i.e. colorectal cancer, ulcers and other ailments. However, there is a risk of bleeding in the lower gastrointestinal (GI) tract while maneuvering endoscopes. This may be due to perforations, hemorrhaging, polyps, diverticuli or post-biopsy complications. Thus, it is essential for the surgeon to be able to detect bleeding at the site and evaluate the severity of blood leakage. This paper presents a soft sensor that can detect the presence of blood at the bleeding site during colonoscopies. The sensor consists of optical waveguides that interface with a microfluidic channel. Blood flow causes absorption and scattering of incident light that can be picked up by the optical sensing apparatus via light transmission through the waveguide. The surgeon can be alerted when bleeding occurs through a graphical user interface. The device is compact and measures only 1 mm thick. This allows the sensor to be circumferentially mounted onto a colonoscope at different locations. The sensor is able to record the presence of blood as an optical loss, rapidly detect the presence of blood in under 100 milliseconds as it enters the microchannel, and differentiate between gastric fluid and blood through changes in measured optical loss.
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Affiliation(s)
- Arincheyan Gerald
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
| | - Max McCandless
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
| | - Avani Sheth
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Hiroyuki Aihara
- Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
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5
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Konoplev G, Agafonova D, Bakhchova L, Mukhin N, Kurachkina M, Schmidt MP, Verlov N, Sidorov A, Oseev A, Stepanova O, Kozyrev A, Dmitriev A, Hirsch S. Label-Free Physical Techniques and Methodologies for Proteins Detection in Microfluidic Biosensor Structures. Biomedicines 2022; 10:207. [PMID: 35203416 PMCID: PMC8868674 DOI: 10.3390/biomedicines10020207] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/01/2022] [Accepted: 01/11/2022] [Indexed: 12/25/2022] Open
Abstract
Proteins in biological fluids (blood, urine, cerebrospinal fluid) are important biomarkers of various pathological conditions. Protein biomarkers detection and quantification have been proven to be an indispensable diagnostic tool in clinical practice. There is a growing tendency towards using portable diagnostic biosensor devices for point-of-care (POC) analysis based on microfluidic technology as an alternative to conventional laboratory protein assays. In contrast to universally accepted analytical methods involving protein labeling, label-free approaches often allow the development of biosensors with minimal requirements for sample preparation by omitting expensive labelling reagents. The aim of the present work is to review the variety of physical label-free techniques of protein detection and characterization which are suitable for application in micro-fluidic structures and analyze the technological and material aspects of label-free biosensors that implement these methods. The most widely used optical and impedance spectroscopy techniques: absorption, fluorescence, surface plasmon resonance, Raman scattering, and interferometry, as well as new trends in photonics are reviewed. The challenges of materials selection, surfaces tailoring in microfluidic structures, and enhancement of the sensitivity and miniaturization of biosensor systems are discussed. The review provides an overview for current advances and future trends in microfluidics integrated technologies for label-free protein biomarkers detection and discusses existing challenges and a way towards novel solutions.
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Affiliation(s)
- Georgii Konoplev
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
| | - Darina Agafonova
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
| | - Liubov Bakhchova
- Institute for Automation Technology, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg, Germany;
| | - Nikolay Mukhin
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
- Department of Engineering, University of Applied Sciences Brandenburg, 14770 Brandenburg an der Havel, Germany; (M.K.); (S.H.)
| | - Marharyta Kurachkina
- Department of Engineering, University of Applied Sciences Brandenburg, 14770 Brandenburg an der Havel, Germany; (M.K.); (S.H.)
| | - Marc-Peter Schmidt
- Faculty of Electrical Engineering, University of Applied Sciences Dresden, 01069 Dresden, Germany;
| | - Nikolay Verlov
- Molecular and Radiation Biophysics Division, Petersburg Nuclear Physics Institute Named by B.P. Konstantinov, National Research Centre Kurchatov Institute, 188300 Gatchina, Russia;
| | - Alexander Sidorov
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
- Fuculty of Photonics, ITMO University, 197101 Saint Petersburg, Russia
| | - Aleksandr Oseev
- FEMTO-ST Institute, CNRS UMR-6174, University Bourgogne Franche-Comté, 25000 Besançon, France;
| | - Oksana Stepanova
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
| | - Andrey Kozyrev
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
| | - Alexander Dmitriev
- Department of Ecological Physiology, Federal State Budgetary Scientific Institution “Institute of Experimental Medicine” (FSBSI “IEM”), 197376 Saint Petersburg, Russia;
| | - Soeren Hirsch
- Department of Engineering, University of Applied Sciences Brandenburg, 14770 Brandenburg an der Havel, Germany; (M.K.); (S.H.)
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Abstract
Optofluidics represents the interaction of light and fluids on a chip that integrates microfluidics and optics, which provides a promising optical platform for manipulating and analyzing fluid samples. Recent years have witnessed a substantial growth in optofluidic devices, including the integration of optical and fluidic control units, the incorporation of diverse photonic nanostructures, and new applications. All these advancements have enabled the implementation of optofluidics with improved performance. In this review, the recent advances of fabrication techniques and cutting-edge applications of optofluidic devices are presented, with a special focus on the developments of imaging and sensing. Specifically, the optofluidic based imaging techniques and applications are summarized, including the high-throughput cytometry, biochemical analysis, and optofluidic nanoparticle manipulation. The optofluidic sensing section is categorized according to the modulation approaches and the transduction mechanisms, represented by absorption, reflection/refraction, scattering, and plasmonics. Perspectives on future developments and promising avenues in the fields of optofluidics are also provided.
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Zhou M, Shi X, Li X, Xiao G, Liang L, Ju J, Wang F, Xia Q, Sun W, Qiao Y, Yu L, Lu Z. Constructing Silk Fibroin-Based Three-Dimensional Microfluidic Devices via a Tape Mask-Assisted Multiple-Step Etching Technique. ACS APPLIED BIO MATERIALS 2021; 4:8039-8048. [PMID: 35006785 DOI: 10.1021/acsabm.1c00948] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Regenerated silk fibroin (RSF) has been regarded as a very promising biomaterial for the preparation of microfluidic devices. However, the facile and low-cost fabrication of three-dimensional (3D) RSF microfluidic devices is still a great challenge. Herein, we developed a tape-mask-assisted multiple-step etching technique to fabricate 3D microfluidic devices based on water-annealed RSF films. Several rounds of tape adhesion- or peeling-etching cycles need to be conducted to produce 3D features on the RSF films with the LiBr aqueous solution as the etchant. The water-annealed RSF films could be effectively etched with 1.0 g·mL-1 LiBr solution at 60 °C. The shape, width, and height of the 3D structures could be precisely tailored by controlling the mask pattern, etching conditions, and the number of etchings. Using the tape adhesion- and peeling-assisted multiple-etching techniques, the convex-pyramid-shaped and the concave-step-shaped structures could be successfully prepared on the RSF films, respectively. The RSF-film-based 3D micromixers and microfluidic separator were also manufactured with the proposed approach, exhibiting excellent liquid mixing and size-dependent particle sorting capabilities, respectively. The enzymatic degradation of RSF-film-based devices was also investigated to show their environmental friendliness. This work may not only provide a facile and low-cost method for the fabrication of RSF-based 3D microfluidic devices but also extend the applications of RSF in the fields of biomedical and chemical analysis.
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Affiliation(s)
- Mengyuan Zhou
- Institute for Clean Energy & Advanced Materials, School of Materials & Energy, Southwest University, 2 Tiansheng Road, Chongqing 400715, P. R. China
| | - Xuemei Shi
- Institute for Clean Energy & Advanced Materials, School of Materials & Energy, Southwest University, 2 Tiansheng Road, Chongqing 400715, P. R. China
| | - Xiaobai Li
- Institute for Clean Energy & Advanced Materials, School of Materials & Energy, Southwest University, 2 Tiansheng Road, Chongqing 400715, P. R. China.,Sannuo Biosensing Company Limited, 265 Guyuan Road, Changsha, Hunan 410221, P. R. China
| | - Gang Xiao
- Institute for Clean Energy & Advanced Materials, School of Materials & Energy, Southwest University, 2 Tiansheng Road, Chongqing 400715, P. R. China
| | - Liping Liang
- Institute for Clean Energy & Advanced Materials, School of Materials & Energy, Southwest University, 2 Tiansheng Road, Chongqing 400715, P. R. China
| | - Jun Ju
- Institute for Clean Energy & Advanced Materials, School of Materials & Energy, Southwest University, 2 Tiansheng Road, Chongqing 400715, P. R. China
| | - Feng Wang
- Biological Science Research Center, Academy for Advanced Interdisciplinary Studies, Southwest University, Chongqing 400715, P. R. China
| | - Qingyou Xia
- Biological Science Research Center, Academy for Advanced Interdisciplinary Studies, Southwest University, Chongqing 400715, P. R. China
| | - Wei Sun
- Key Laboratory of Laser Technology and Optoelectronic Functional Materials of Hainan Province, College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158, P. R. China
| | - Yan Qiao
- Institute for Clean Energy & Advanced Materials, School of Materials & Energy, Southwest University, 2 Tiansheng Road, Chongqing 400715, P. R. China
| | - Ling Yu
- Institute for Clean Energy & Advanced Materials, School of Materials & Energy, Southwest University, 2 Tiansheng Road, Chongqing 400715, P. R. China
| | - Zhisong Lu
- Institute for Clean Energy & Advanced Materials, School of Materials & Energy, Southwest University, 2 Tiansheng Road, Chongqing 400715, P. R. China
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Tang J, Qiu G, Zhang X, Wang J. A 3D-cascade-microlens optofluidic chip for refractometry with adjustable sensitivity. LAB ON A CHIP 2021; 21:3784-3792. [PMID: 34581391 DOI: 10.1039/d1lc00570g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Refractive index (RI) sensing as a label-free and non-invasive method has been playing an important role in industrial metrology, biochemical detection, and environmental analysis. Due to the combined advantages of microoptics and microfluidics, optofluidic RI sensors have attracted growing interest. Despite a variety of prototypes of optofluidic RI sensors, comprehensive improvement in sensitivity, detection range, fabrication procedures and cost can still bring substantial benefits to the field. In this work, we fabricated a 3D-cascade-microlens optofluidic chip (3DCMOC) for RI sensing. Two-photon stereolithography was employed to fabricate the chip mold, with which the 3DCMOC could be easily manufactured via mold replication. By virtue of integrating four detection channels configured with different numbers (1, 3, 5, and 7) of cascaded microlenses within the 3DCMOC, adjustable sensitivity for RI sensing has been demonstrated through measuring standard sucrose solutions. It was found that the seven-microlens configuration achieved an excellent sensitivity (mean: 21 ± 5 AU·RIU (refractive index unit)-1) and resolution (mean: 3.8 × 10-5 ± 0.9 × 10-5 RIU) at a cost of a narrow linear dynamic range (LDR, 1.3326-1.3548). In contrast, the single-microlens configuration led to an extended LDR (1.3326-1.5120 tested) despite the lower sensitivity (mean: 2.6 ± 0.2 AU·RIU-1) and resolution (mean: 1.5 × 10-4 ± 0.1 × 10-4 RIU). Furthermore, the use of the 3DCMOC was investigated via real-time salinity sensing and analysis of urine specific gravity.
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Affiliation(s)
- Jiukai Tang
- Institute of Environmental Engineering, ETH Zürich, Zürich 8093, Switzerland.
- Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Guangyu Qiu
- Institute of Environmental Engineering, ETH Zürich, Zürich 8093, Switzerland.
- Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Xiaole Zhang
- Institute of Environmental Engineering, ETH Zürich, Zürich 8093, Switzerland.
- Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Jing Wang
- Institute of Environmental Engineering, ETH Zürich, Zürich 8093, Switzerland.
- Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
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Tang J, Cao X, Qiu G, deMello A, Wang J. Optical-Switch-Enabled Microfluidics for Sensitive Multichannel Colorimetric Analysis. Anal Chem 2021; 93:6784-6791. [PMID: 33877822 DOI: 10.1021/acs.analchem.1c00674] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The implementation of colorimetric analysis within microfluidic environments engenders significant benefits with respect to reduced sample and reagent consumption, system miniaturization, and real-time measurement of flowing samples. That said, conventional approaches to colorimetric analysis within microfluidic channels are hampered by short optical pathlengths and single-channel configurations, which lead to poor detection sensitivities and low analytical throughputs. Although the use of multiplexed light source/photodetector modules allows for multichannel analysis, such configurations significantly increase both instrument complexity and cost. To address these issues, we present a four-channel colorimetric measurement scheme within an optical-switch-enabled microfluidic chip (OSEMC) fabricated by two-photon stereolithography. The integration of optical switches enables sequential signal readout from each detection channel, and thus, only a single light source and a photodetector are required for operation. Optical switches can be controlled in a bespoke manner by changing the medium in the switch channel between a "light-transmitting" fluid and a "light-blocking" fluid using pneumatic microvalves. Such optical switches are characterized by fast response times (approximately 200 ms), tunable switching frequencies (between 0.1 and 1.0 Hz studied), and excellent stability. Operational performance demonstrates both good sensitivity and reproducibility through the colorimetric analysis of nitrite and ammonium samples using four detection channels. Furthermore, the use of OSEMC for parallel and real-time analysis of flowing samples is investigated via characterization of the adsorption kinetics of tartrazine on activated charcoal and the catalytic reaction kinetics of horseradish peroxidase (HRP).
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Affiliation(s)
- Jiukai Tang
- Institute of Environmental Engineering, ETH Zürich, Zürich 8093, Switzerland.,Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Xiaobao Cao
- Institute of Chemical and Bioengineering, ETH Zürich, Vladimir Prelog Weg 1, Zürich 8093, Switzerland
| | - Guangyu Qiu
- Institute of Environmental Engineering, ETH Zürich, Zürich 8093, Switzerland.,Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Andrew deMello
- Institute of Chemical and Bioengineering, ETH Zürich, Vladimir Prelog Weg 1, Zürich 8093, Switzerland
| | - Jing Wang
- Institute of Environmental Engineering, ETH Zürich, Zürich 8093, Switzerland.,Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
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