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Flürenbrock F, Korn L, Schulte D, Podgoršak A, Chomarat J, Hug J, Hungerland T, Holzer C, Iselin D, Krebs L, Weiss R, Oertel MF, Stieglitz L, Weisskopf M, Meboldt M, Zeilinger MN, Schmid Daners M. VIEshunt: towards a ventricular intelligent and electromechanical shunt for hydrocephalus therapy. Fluids Barriers CNS 2025; 22:28. [PMID: 40087797 PMCID: PMC11907855 DOI: 10.1186/s12987-025-00629-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 01/31/2025] [Indexed: 03/17/2025] Open
Abstract
BACKGROUND Shunt systems for hydrocephalus therapy are commonly based on passive mechanical pressure valves that are driven by the intracranial, intra-abdominal, and hydrostatic pressure. The differential pressure acting on the valve determines the drainage rate of cerebrospinal fluid (CSF) but is not a gauge of the physiological condition of the patient. Internal and external influences can cause over- or underdrainage and lead to pathological levels of intracranial pressure (ICP). METHODS The first prototype of a ventricular intelligent and electromechanical shunt (VIEshunt) is developed, tested, and compared with previous efforts towards the development of a smart shunt. Its key components are a micro pump, a flow meter, a pressure sensor, an inertial measurement unit, a wireless communication interface, and a microcontroller. The VIEshunt prototype was tested in vitro using a hardware-in-the-loop (HiL) test bench that runs real-time patient simulations involving changes in intracranial and intra-abdominal pressure, as well as changes in posture ranging between supine and upright position. The prototype was subsequently tested in an in vivo pilot study based on an acute ovine animal model (n=1) with infusions of artificial CSF. RESULTS During 24 h in vitro testing, the prototype detected the simulated posture changes of the patient and automatically adapted the controller reference. The posture-specific ICP references of 12 mmHg for supine and -3 mmHg for upright position were tracked without offset, thus preventing adverse over- and underdrainage during the investigated HiL test scenario. During acute in vivo testing, the prototype first regulated the mean ICP of a sheep from 22 mmHg down to 20 mmHg. Each of the three subsequent intraventricular bolus infusions of 1 mL saline solution increased mean ICP by approximately 11 mmHg. While natural absorption alone decreased ICP by only 5 mmHg within 9 min, the prototype was able to regulate ICP back to the pre-bolus pressure value within 5 min. CONCLUSION The developed VIEshunt prototype is capable of posture-dependent ICP regulation and CSF drainage control. Smart shunt systems based on VIEshunt could improve patient monitoring and enable optimal physiologic therapy by adapting to the individual patient. To derive statistically relevant conclusions for the performance of VIEshunt, future work will focus on the development of a next generation prototype for use in pre-clinical studies.
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Affiliation(s)
- Fabian Flürenbrock
- Institute for Dynamic Systems and Control, ETH Zurich, Zurich, Switzerland.
| | - Leonie Korn
- Institute for Dynamic Systems and Control, ETH Zurich, Zurich, Switzerland
| | - Dominik Schulte
- Institute for Dynamic Systems and Control, ETH Zurich, Zurich, Switzerland
| | | | - Joris Chomarat
- Product Development Group Zurich, ETH Zurich, Zurich , Switzerland
| | - Janina Hug
- Product Development Group Zurich, ETH Zurich, Zurich , Switzerland
| | - Tiago Hungerland
- Product Development Group Zurich, ETH Zurich, Zurich , Switzerland
| | - Caroline Holzer
- Product Development Group Zurich, ETH Zurich, Zurich , Switzerland
| | - David Iselin
- Product Development Group Zurich, ETH Zurich, Zurich , Switzerland
| | - Luca Krebs
- Product Development Group Zurich, ETH Zurich, Zurich , Switzerland
| | - Rosina Weiss
- Product Development Group Zurich, ETH Zurich, Zurich , Switzerland
| | - Markus F Oertel
- Department of Neurosurgery, University Hospital Zurich, Zurich , Switzerland
| | - Lennart Stieglitz
- Department of Neurosurgery, University Hospital Zurich, Zurich , Switzerland
| | - Miriam Weisskopf
- Center for Preclinical Development, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Mirko Meboldt
- Product Development Group Zurich, ETH Zurich, Zurich , Switzerland
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Hong S, Coté G. Minimization of Parasitic Capacitance between Skin and Ag/AgCl Dry Electrodes. MICROMACHINES 2024; 15:907. [PMID: 39064418 PMCID: PMC11278634 DOI: 10.3390/mi15070907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Revised: 07/04/2024] [Accepted: 07/10/2024] [Indexed: 07/28/2024]
Abstract
Conventional dry electrodes often yield unstable results due to the presence of parasitic capacitance between the flat electrode surface and the non-uniform skin interface. To address this issue, a gel is typically placed between the electrodes to minimize parasitic capacitance. However, this approach has the drawbacks of being unsuitable for repeated use, limited lifetime due to gel evaporation, and the possibility of developing skin irritation. This is particularly problematic in underserved areas since, due to the cost of disposable wet electrodes, they often sterilize and reuse dry electrodes. In this study, we propose a method to neutralize the effects of parasitic capacitance by attaching high-value capacitors to the electrodes in parallel, specifically when applied to pulse wave monitoring through bioimpedance. Skin capacitance can also be mitigated due to the serial connection, enabling stable reception of arterial pulse signals through bioimpedance circuits. A high-frequency structure simulator (HFSS) was first used to simulate the capacitance when injection currents flow into the arteries through the bioimpedance circuits. We also used the simulation to investigate the effects of add-on capacitors. Lastly, we conducted preliminary comparative analyses between wet electrodes and dry electrodes in vivo with added capacitance values ranging from 100 pF to 1 μF, altering capacitance magnitudes by factors of 100. As a result, we obtained a signal-to-noise ratio (SNR) that was 8.2 dB higher than that of dry electrodes. Performance was also shown to be comparable to wet electrodes, with a reduction of only 0.4 dB using 1 μF. The comparative results demonstrate that the addition of capacitors to the electrodes has the potential to allow for performance similar to that of wet electrodes for bioimpedance pulse rate monitoring and could potentially be used for other applications of dry electrodes.
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Affiliation(s)
- Sungcheol Hong
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA;
| | - Gerard Coté
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA;
- Department of Electrical Engineering, Texas A&M University, College Station, TX 77843, USA
- Center for Remote Health Technologies and Systems, Texas A&M Engineering Experiment Station, Texas A&M University, College Station, TX 77843, USA
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Hong S, Coté G. Development of a Tetherless Bioimpedance Device That Uses Morphologic Changes to Predict Blood Flow Restrictions Mimicking Peripheral Artery Disease Progression. BIOSENSORS 2024; 14:286. [PMID: 38920590 PMCID: PMC11202059 DOI: 10.3390/bios14060286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 05/24/2024] [Accepted: 05/31/2024] [Indexed: 06/27/2024]
Abstract
A tetherless multi-targeted bioimpedance device was designed, modeled, built, and tested for measuring arterial pulse and, using morphological analysis, its potential for monitoring blood flow restrictions that mimic Peripheral Artery Disease (PAD) was assessed across multiple peripheral arteries. Specifically, we first developed a small form factor, tetherless, bioimpedance device, based on high-frequency structure simulator (HFSS) simulations. After designing and building the device we then tested it in vivo on human subjects on multiple arteries and found that we did not need to modify the gain on the device compared to the bench top system. Further, it was found that changes in the morphology of the bioimpedance signal over time, depicted through the ratio of the first and second harmonic in the signal frequency, could be used to predict blood flow restrictions that mimic peripheral artery disease (PAD). The HFSS simulations helped guide the modulation frequency selection and the placement of the bioimpedance electrodes. We built the device and compared it to two commercially available bioimpedance devices and it was shown to demonstrate a distinct advantage in its multi-target capability, enabling more accurate pulse measurements from different arteries without the need for tuning the circuit for each artery. Comparing the ratio of the 1st and 2nd harmonics as a function of the blood flow restriction, the two commercial devices showed a maximum error across arteries of between 22% and 27% depending on the measurement location, whereas our system consistently displayed a stable value of just below 4%. With this system, there is the potential for comprehensive and personalized medical examinations for PAD at the point of care (POC).
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Affiliation(s)
- Sungcheol Hong
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA;
| | - Gerard Coté
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA;
- Department of Electrical Engineering, Texas A&M University, College Station, TX 77843, USA
- Center for Remote Health Technologies and Systems, Texas A&M Engineering Experiment Station, Texas A&M University, College Station, TX 77843, USA
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Hatami-Fard G, Anastasova-Ivanova S. Advancements in Cerebrospinal Fluid Biosensors: Bridging the Gap from Early Diagnosis to the Detection of Rare Diseases. SENSORS (BASEL, SWITZERLAND) 2024; 24:3294. [PMID: 38894085 PMCID: PMC11174891 DOI: 10.3390/s24113294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 05/13/2024] [Accepted: 05/17/2024] [Indexed: 06/21/2024]
Abstract
Cerebrospinal fluid (CSF) is a body fluid that can be used for the diagnosis of various diseases. However, CSF collection requires an invasive and painful procedure called a lumbar puncture (LP). This procedure is applied to any patient with a known risk of central nervous system (CNS) damage or neurodegenerative disease, regardless of their age range. Hence, this can be a very painful procedure, especially in infants and elderly patients. On the other hand, the detection of disease biomarkers in CSF makes diagnoses as accurate as possible. This review aims to explore novel electrochemical biosensing platforms that have impacted biomedical science. Biosensors have emerged as techniques to accelerate the detection of known biomarkers in body fluids such as CSF. Biosensors can be designed and modified in various ways and shapes according to their ultimate applications to detect and quantify biomarkers of interest. This process can also significantly influence the detection and diagnosis of CSF. Hence, it is important to understand the role of this technology in the rapidly progressing field of biomedical science.
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Affiliation(s)
- Ghazal Hatami-Fard
- The Hamlyn Centre, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
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Zarrin DA, Jafari M, Kim W, Colby GP. A novel ventriculoperitoneal shunt flow sensor based on electrically induced spatial variation in cerebrospinal fluid charge density. Front Bioeng Biotechnol 2024; 11:1339831. [PMID: 38283172 PMCID: PMC10814118 DOI: 10.3389/fbioe.2023.1339831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 12/26/2023] [Indexed: 01/30/2024] Open
Abstract
Introduction: Ventriculoperitoneal (VP) shunts divert cerebrospinal fluid (CSF) out of cerebral ventricles in patients with hydrocephalus or elevated intracranial pressure (ICP). Despite high failure rates, there exist limited clinically viable solutions for long-term and continuous outpatient monitoring of CSF flow rate through VP shunts. We present a novel, low-power method for sensing analog CSF flow rate through a VP shunt premised on induced spatial electrical charge variation. Methods: Two geometric variants of the proposed sensing mechanism were prototyped: linear wire (P1) and cylindrical (P2) electrodes. Normal saline was gravity-driven through P1 and a commercially available shunt system in series. True flow rates were measured using a high-precision analytical balance. Subsequently, artificial CSF was driven by a programmable syringe pump through P2. Flow rate prediction models were empirically derived and tested. Sensor response was also assessed during simulated obstruction trials. Finally, power consumption per flow measurement was measured. Results: P1 (17 mm long) and P2 (22 mm long) averaged 7.2% and 4.2% error, respectively, in flow rate measurement from 0.01 to 0.90 mL/min. Response curves exhibited an appreciably flattened profile during obstruction trials compared to non-obstructed states. P2 consumed 37.5 µJoules per flow measurement. Conclusion: We propose a novel method for accurately sensing CSF flow rate through a VP shunt and validate this method at the benchtop with normal saline and artificial CSF over a board range of flows (0.01-0.90 mL/min). The sensing element is highly power efficient, compact, insertable into existing shunt and valve assemblies, and does not alter CSF flow mechanics.
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Affiliation(s)
- David A. Zarrin
- David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Matiar Jafari
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, United States
| | - Won Kim
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, United States
| | - Geoffrey P. Colby
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, United States
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Veletić M, Apu EH, Simić M, Bergsland J, Balasingham I, Contag CH, Ashammakhi N. Implants with Sensing Capabilities. Chem Rev 2022; 122:16329-16363. [PMID: 35981266 DOI: 10.1021/acs.chemrev.2c00005] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Because of the aging human population and increased numbers of surgical procedures being performed, there is a growing number of biomedical devices being implanted each year. Although the benefits of implants are significant, there are risks to having foreign materials in the body that may lead to complications that may remain undetectable until a time at which the damage done becomes irreversible. To address this challenge, advances in implantable sensors may enable early detection of even minor changes in the implants or the surrounding tissues and provide early cues for intervention. Therefore, integrating sensors with implants will enable real-time monitoring and lead to improvements in implant function. Sensor integration has been mostly applied to cardiovascular, neural, and orthopedic implants, and advances in combined implant-sensor devices have been significant, yet there are needs still to be addressed. Sensor-integrating implants are still in their infancy; however, some have already made it to the clinic. With an interdisciplinary approach, these sensor-integrating devices will become more efficient, providing clear paths to clinical translation in the future.
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Affiliation(s)
- Mladen Veletić
- Department of Electronic Systems, Norwegian University of Science and Technology, 7491 Trondheim, Norway.,The Intervention Centre, Technology and Innovation Clinic, Oslo University Hospital, 0372 Oslo, Norway
| | - Ehsanul Hoque Apu
- Institute for Quantitative Health Science and Engineering (IQ) and Department of Biomedical Engineering (BME), Michigan State University, East Lansing, Michigan 48824, United States.,Division of Hematology and Oncology, Department of Internal Medicine, Michigan Medicine, University of Michigan, Ann Arbor, Michigan 48105, United States
| | - Mitar Simić
- Faculty of Electrical Engineering, University of Banja Luka, 78000 Banja Luka, Bosnia and Herzegovina
| | - Jacob Bergsland
- The Intervention Centre, Technology and Innovation Clinic, Oslo University Hospital, 0372 Oslo, Norway
| | - Ilangko Balasingham
- Department of Electronic Systems, Norwegian University of Science and Technology, 7491 Trondheim, Norway.,The Intervention Centre, Technology and Innovation Clinic, Oslo University Hospital, 0372 Oslo, Norway
| | - Christopher H Contag
- Institute for Quantitative Health Science and Engineering (IQ) and Department of Biomedical Engineering (BME), Michigan State University, East Lansing, Michigan 48824, United States
| | - Nureddin Ashammakhi
- Institute for Quantitative Health Science and Engineering (IQ) and Department of Biomedical Engineering (BME), Michigan State University, East Lansing, Michigan 48824, United States.,Department of Bioengineering, University of California, Los Angeles, California 90095, United States
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Wang JH, Tavoosi J, Mohammadzadeh A, Mobayen S, Asad JH, Assawinchaichote W, Vu MT, Skruch P. Non-Singleton Type-3 Fuzzy Approach for Flowmeter Fault Detection: Experimental Study in a Gas Industry. SENSORS 2021; 21:s21217419. [PMID: 34770723 PMCID: PMC8587827 DOI: 10.3390/s21217419] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 11/16/2022]
Abstract
The main contribution of this paper is to develop a new flowmeter fault detection approach based on optimized non-singleton type-3 (NT3) fuzzy logic systems (FLSs). The introduced method is implemented on an experimental gas industry plant. The system is modeled by NT3FLSs, and the faults are detected by comparison of measured end estimated signals. In this scheme, the detecting performance depends on the estimation and modeling performance. The suggested NT3FLS is used because of the existence of a high level of measurement errors and uncertainties in this problem. The designed NT3FLS with uncertain footprint-of-uncertainty (FOU), fuzzy secondary memberships and adaptive non-singleton fuzzification results in a powerful tool for modeling signals immersed in noise and error. The level of non-singleton fuzzification and membership parameters are tuned by maximum correntropy (MC) unscented Kalman filter (KF), and the rule parameters are learned by correntropy KF (CKF) with fuzzy kernel size. The suggested learning algorithms can handle the non-Gaussian noises that are common in industrial applications. The various types of flowmeters are investigated, and the effect of common faults are examined. It is shown that the suggested approach can detect the various faults with good accuracy in comparison with conventional approaches.
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Affiliation(s)
- Jing-he Wang
- School of Economics and Finance, Huaqiao University, Quanzhou 362021, China;
| | - Jafar Tavoosi
- Department of Electrical Engineering, Ilam University, Ilam 69315516, Iran;
| | | | - Saleh Mobayen
- Future Technology Research Center, National Yunlin University of Science and Technology, Douliu 64002, Taiwan
- Correspondence: (S.M.); (W.A.)
| | - Jihad H. Asad
- Department of Physics, Faculty of Applied Sciences, Palestine Technical University, Tulkarm P.O. Box 7, Palestine;
| | - Wudhichai Assawinchaichote
- Department of Electronic and Telecommunication Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand
- Correspondence: (S.M.); (W.A.)
| | - Mai The Vu
- School of Intelligent Mechatronics Engineering, Sejong University, Seoul 05006, Korea;
| | - Paweł Skruch
- Department of Automatic Control and Robotics, AGH University of Science and Technology, 30-059 Kraków, Poland;
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