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Hussain NM, Amin B, O’Halloran M, Elahi A. Development and Characterization of Interstitial-Fluid-Mimicking Solutions for Pre-Clinical Assessment of Hypoxia. Diagnostics (Basel) 2023; 13:3125. [PMID: 37835868 PMCID: PMC10572912 DOI: 10.3390/diagnostics13193125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 09/20/2023] [Accepted: 09/29/2023] [Indexed: 10/15/2023] Open
Abstract
Asphyxia, a leading cause of illness and death in newborns, can be improved by early detection and management. Arterial blood gas (ABG) analysis is commonly used to diagnose and manage asphyxia, but it is invasive and carries risks. Dermal interstitial fluid (ISF) is an alternative physiological fluid that can provide valuable information about a person's health. ISF is more sensitive to severe hypoxia and metabolic disorders compared to blood, making it an attractive option for minimally invasive asphyxia detection using biosensors. However, obtaining ISF samples from humans is challenging due to ethical concerns and sampling difficulties. To address this, researchers are developing ISF-mimicking solutions as substitutes for early testing and evaluation of biosensors. This paper focuses on the development of these solutions for bench-based testing and validation of continuous asphyxia-monitoring biosensors. With an understanding of the factors influencing system quality and performance, these solutions can aid in the design of biosensors for in vivo monitoring of dermal ISF. Monitoring interstitial fluid pH levels can provide valuable insights into the severity and progression of asphyxia, aiding in accurate diagnosis and informed treatment decisions. In this study, buffer solutions were prepared to mimic the pH of ISF, and their electrical properties were analyzed. The results suggest that certain buffers can effectively mimic metabolic acidosis associated with asphyxia (pH < 7.30), while others can mimic metabolic alkalosis (pH > 7.45). Overall, this research contributes to the development of ISF-mimicking solutions and lays the groundwork for biosensor systems that monitor dermal ISF in real time.
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Affiliation(s)
- Nadia Muhammad Hussain
- Translational Medical Device Lab, University of Galway, H91 TK33 Galway, Ireland; (B.A.); (M.O.); (A.E.)
- Electrical and Electronic Engineering, University of Galway, H91 TK33 Galway, Ireland
| | - Bilal Amin
- Translational Medical Device Lab, University of Galway, H91 TK33 Galway, Ireland; (B.A.); (M.O.); (A.E.)
- Electrical and Electronic Engineering, University of Galway, H91 TK33 Galway, Ireland
- School of Medicine, University of Galway, H91 TK33 Galway, Ireland
| | - Martin O’Halloran
- Translational Medical Device Lab, University of Galway, H91 TK33 Galway, Ireland; (B.A.); (M.O.); (A.E.)
- Electrical and Electronic Engineering, University of Galway, H91 TK33 Galway, Ireland
- School of Medicine, University of Galway, H91 TK33 Galway, Ireland
| | - Adnan Elahi
- Translational Medical Device Lab, University of Galway, H91 TK33 Galway, Ireland; (B.A.); (M.O.); (A.E.)
- Electrical and Electronic Engineering, University of Galway, H91 TK33 Galway, Ireland
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2
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Villasana Y, Moradi N, Navas‐Cárdenas C, Patience GS. Experimental methods in chemical engineering:
pH. CAN J CHEM ENG 2022. [DOI: 10.1002/cjce.24393] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Yanet Villasana
- Biomass Laboratory, Biomass to Resources Group, Universidad Regional Amazónica IKIAM 150150 Tena Ecuador
| | - Nooshin Moradi
- Chemical Engineering, Polytechnique Montréal, C.P. 6079, Succ. “CV”, Montréal Québec Canada
| | - Carlos Navas‐Cárdenas
- Biomass Laboratory, Biomass to Resources Group, Universidad Regional Amazónica IKIAM 150150 Tena Ecuador
- School of Chemical Sciences and Engineering, Universidad Yachay Tech Urcuquí Ecuador
| | - Gregory S. Patience
- Chemical Engineering, Polytechnique Montréal, C.P. 6079, Succ. “CV”, Montréal Québec Canada
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Dulay S, Rivas L, Pla L, Berdún S, Eixarch E, Gratacós E, Illa M, Mir M, Samitier J. Fetal ischemia monitoring with in vivo implanted electrochemical multiparametric microsensors. J Biol Eng 2021; 15:28. [PMID: 34930385 PMCID: PMC8691007 DOI: 10.1186/s13036-021-00280-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/30/2021] [Indexed: 12/15/2022] Open
Abstract
Under intrauterine growth restriction (IUGR), abnormal attainment of the nutrients and oxygen by the fetus restricts the normal evolution of the prenatal causing in many cases high morbidity being one of the top-ten causes of neonatal death. The current gold standards in hospitals to detect this relevant problem is the clinical observation by echography, cardiotocography and Doppler. These qualitative techniques are not conclusive and requires risky invasive fetal scalp blood testing and/or amniocentesis. We developed micro-implantable multiparametric electrochemical sensors for measuring ischemia in real time in fetal tissue and vascular. This implantable technology is designed to continuous monitoring for an early detection of ischemia to avoid potential fetal injury. Two miniaturized electrochemical sensors were developed based on oxygen and pH detection. The sensors were optimized in vitro under controlled concentration, to assess the selectivity and sensitivity required. The sensors were then validated in vivo in the ewe fetus model, by means of their insertion in the muscle leg and inside the iliac artery of the fetus. Ischemia was achieved by gradually obstructing the umbilical cord to regulate the amount of blood reaching the fetus. An important challenge in fetal monitoring is the detection of low levels of oxygen and pH changes under ischemic conditions, requiring high sensitivity sensors. Significant differences were observed in both; pH and pO2 sensors under changes from normoxia to hypoxia states in the fetus tissue and vascular with both sensors. Herein, we demonstrate the feasibility of the developed sensors for future fetal monitoring in medical applications.
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Affiliation(s)
- Samuel Dulay
- Nanobioengineering group, Institute for Bioengineering of Catalonia (IBEC) Barcelona Institute of Science and Technology (BIST), 12 Baldiri Reixac 15-21, 08028, Barcelona, Spain
| | - Lourdes Rivas
- Nanobioengineering group, Institute for Bioengineering of Catalonia (IBEC) Barcelona Institute of Science and Technology (BIST), 12 Baldiri Reixac 15-21, 08028, Barcelona, Spain
| | - Laura Pla
- Fetal Medicine Research Center, BCNatal. Hospital Clínic and Hospital Sant Joan de Déu, Universitat de Barcelona, Building Helios 2, Sabino Arana Street 1, 08028, Barcelona, Spain
| | - Sergio Berdún
- Fetal Medicine Research Center, BCNatal. Hospital Clínic and Hospital Sant Joan de Déu, Universitat de Barcelona, Building Helios 2, Sabino Arana Street 1, 08028, Barcelona, Spain
| | - Elisenda Eixarch
- Fetal Medicine Research Center, BCNatal. Hospital Clínic and Hospital Sant Joan de Déu, Universitat de Barcelona, Building Helios 2, Sabino Arana Street 1, 08028, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Eduard Gratacós
- Fetal Medicine Research Center, BCNatal. Hospital Clínic and Hospital Sant Joan de Déu, Universitat de Barcelona, Building Helios 2, Sabino Arana Street 1, 08028, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Miriam Illa
- Fetal Medicine Research Center, BCNatal. Hospital Clínic and Hospital Sant Joan de Déu, Universitat de Barcelona, Building Helios 2, Sabino Arana Street 1, 08028, Barcelona, Spain
| | - Mònica Mir
- Nanobioengineering group, Institute for Bioengineering of Catalonia (IBEC) Barcelona Institute of Science and Technology (BIST), 12 Baldiri Reixac 15-21, 08028, Barcelona, Spain. .,Biomedical Research Networking Center in Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN), Monforte de Lemos 3-5, Pabellón 11, 28029, Madrid, Spain. .,Department of Electronics and Biomedical Engineering, University of Barcelona, Martí i Franquès 1, 08028, Barcelona, Spain.
| | - Josep Samitier
- Nanobioengineering group, Institute for Bioengineering of Catalonia (IBEC) Barcelona Institute of Science and Technology (BIST), 12 Baldiri Reixac 15-21, 08028, Barcelona, Spain.,Biomedical Research Networking Center in Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN), Monforte de Lemos 3-5, Pabellón 11, 28029, Madrid, Spain.,Department of Electronics and Biomedical Engineering, University of Barcelona, Martí i Franquès 1, 08028, Barcelona, Spain
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4
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Dulay S, Rivas L, Miserere S, Pla L, Berdún S, Parra J, Eixarch E, Gratacós E, Illa M, Mir M, Samitier J. in vivo Monitoring with micro-implantable hypoxia sensor based on tissue acidosis. Talanta 2020; 226:122045. [PMID: 33676640 DOI: 10.1016/j.talanta.2020.122045] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 12/17/2020] [Accepted: 12/21/2020] [Indexed: 12/22/2022]
Abstract
Hypoxia is a common medical problem, sometimes difficult to detect and caused by different situations. Control of hypoxia is of great medical importance and early detection is essential to prevent life threatening complications. However, the few current methods are invasive, expensive, and risky. Thus, the development of reliable and accurate sensors for the continuous monitoring of hypoxia is of vital importance for clinical monitoring. Herein, we report an implantable sensor to address these needs. The developed device is a low-cost, miniaturised implantable electrochemical sensor for monitoring hypoxia in tissue by means of pH detection. This technology is based on protonation/deprotonation of polypyrrole conductive polymer. The sensor was optimized in vitro and tested in vivo intramuscularly and ex vivo in blood in adult rabbits with respiration-induced hypoxia and correlated with the standard device ePOCTM. The sensor demonstrated excellent sensitivity and reproducibility; 46.4 ± 0.4 mV/pH in the pH range of 4-9 and the selectivity coefficient exhibited low interference activity in vitro. The device was linear (R2 = 0.925) with a low dispersion of the values (n = 11) with a cut-off of 7.1 for hypoxia in vivo and ex vivo. Statistics with one-way ANOVA (α = 0.05), shows statistical differences between hypoxia and normoxia states and the good performance of the pH sensor, which demonstrated good agreement with the standard device. The sensor was stable and functional after 18 months. The excellent results demonstrated the feasibility of the sensors in real-time monitoring of intramuscular tissue and blood for medical applications.
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Affiliation(s)
- Samuel Dulay
- Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC) Barcelona Institute of Science and Technology (BIST), 12 Baldiri Reixac 15-21, Barcelona, 08028, Spain
| | - Lourdes Rivas
- Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC) Barcelona Institute of Science and Technology (BIST), 12 Baldiri Reixac 15-21, Barcelona, 08028, Spain
| | - Sandrine Miserere
- Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC) Barcelona Institute of Science and Technology (BIST), 12 Baldiri Reixac 15-21, Barcelona, 08028, Spain
| | - Laura Pla
- Fetal Medicine Research Center, BCNatal. Hospital Clínic and Hospital Sant Joan de Déu, Universitat de Barcelona. Building Helios 2, Sabino Arana Street 1, 08028, Barcelona, Spain
| | - Sergio Berdún
- Fetal Medicine Research Center, BCNatal. Hospital Clínic and Hospital Sant Joan de Déu, Universitat de Barcelona. Building Helios 2, Sabino Arana Street 1, 08028, Barcelona, Spain
| | - Johanna Parra
- Fetal Medicine Research Center, BCNatal. Hospital Clínic and Hospital Sant Joan de Déu, Universitat de Barcelona. Building Helios 2, Sabino Arana Street 1, 08028, Barcelona, Spain
| | - Elisenda Eixarch
- Fetal Medicine Research Center, BCNatal. Hospital Clínic and Hospital Sant Joan de Déu, Universitat de Barcelona. Building Helios 2, Sabino Arana Street 1, 08028, Barcelona, Spain; Institut D'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
| | - Eduard Gratacós
- Fetal Medicine Research Center, BCNatal. Hospital Clínic and Hospital Sant Joan de Déu, Universitat de Barcelona. Building Helios 2, Sabino Arana Street 1, 08028, Barcelona, Spain; Institut D'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
| | - Míriam Illa
- Fetal Medicine Research Center, BCNatal. Hospital Clínic and Hospital Sant Joan de Déu, Universitat de Barcelona. Building Helios 2, Sabino Arana Street 1, 08028, Barcelona, Spain
| | - Mònica Mir
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Monforte de Lemos 3-5, Pabellón 11, 28029, Madrid, Spain; Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC) Barcelona Institute of Science and Technology (BIST), 12 Baldiri Reixac 15-21, Barcelona, 08028, Spain; Department of Electronics and Biomedical Engineering, Universitat de Barcelona, Martí I Franquès 1, 08028, Barcelona, Spain.
| | - Josep Samitier
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Monforte de Lemos 3-5, Pabellón 11, 28029, Madrid, Spain; Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC) Barcelona Institute of Science and Technology (BIST), 12 Baldiri Reixac 15-21, Barcelona, 08028, Spain; Department of Electronics and Biomedical Engineering, Universitat de Barcelona, Martí I Franquès 1, 08028, Barcelona, Spain
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5
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Effect of pH on the Conductivity of Basidiomycetes DNAs Integrated Within Schottky‐Like Junctions. ChemistrySelect 2020. [DOI: 10.1002/slct.201903643] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Hafezi H, Robertson TL, Moon GD, Au-Yeung KY, Zdeblick MJ, Savage GM. An ingestible sensor for measuring medication adherence. IEEE Trans Biomed Eng 2015; 62:99-109. [PMID: 25069107 DOI: 10.1109/tbme.2014.2341272] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In this paper, we describe the design and performance of the first integrated-circuit microsensor developed for daily ingestion by patients. The ingestible sensor is a device that allows patients, families, and physicians to measure medication ingestion and adherence patterns in real time, relate pharmaceutical compliance to important physiologic metrics, and take appropriate action in response to a patient's adherence pattern and specific health metrics. The design and theory of operation of the device are presented, along with key in-vitro and in-vivo performance results. The chemical, toxicological, mechanical, and electrical safety tests performed to establish the device's safety profile are described in detail. Finally, aggregate results from multiple clinical trials involving 412 patients and 5656 days of system usage are presented to demonstrate the device's reliability and performance as part of an overall digital health feedback system.
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7
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Tahirbegi IB, Alvira M, Mir M, Samitier J. Simple and fast method for fabrication of endoscopic implantable sensor arrays. SENSORS 2014; 14:11416-26. [PMID: 24971473 PMCID: PMC4168460 DOI: 10.3390/s140711416] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 06/10/2014] [Accepted: 06/20/2014] [Indexed: 01/21/2023]
Abstract
Here we have developed a simple method for the fabrication of disposable implantable all-solid-state ion-selective electrodes (ISE) in an array format without using complex fabrication equipment or clean room facilities. The electrodes were designed in a needle shape instead of planar electrodes for a full contact with the tissue. The needle-shape platform comprises 12 metallic pins which were functionalized with conductive inks and ISE membranes. The modified microelectrodes were characterized with cyclic voltammetry, scanning electron microscope (SEM), and optical interferometry. The surface area and roughness factor of each microelectrode were determined and reproducible values were obtained for all the microelectrodes on the array. In this work, the microelectrodes were modified with membranes for the detection of pH and nitrate ions to prove the reliability of the fabricated sensor array platform adapted to an endoscope.
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Affiliation(s)
- I Bogachan Tahirbegi
- Nanobioengineering Laboratory, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac, 10-12, Barcelona 08028, Spain.
| | - Margarita Alvira
- Nanobioengineering Laboratory, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac, 10-12, Barcelona 08028, Spain.
| | - Mònica Mir
- Nanobioengineering Laboratory, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac, 10-12, Barcelona 08028, Spain.
| | - Josep Samitier
- Nanobioengineering Laboratory, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac, 10-12, Barcelona 08028, Spain.
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Tahirbegi IB, Mir M, Schostek S, Schurr M, Samitier J. in vivo ischemia monitoring array for endoscopic surgery. Biosens Bioelectron 2014; 61:124-30. [PMID: 24874655 DOI: 10.1016/j.bios.2014.02.080] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 02/27/2014] [Accepted: 02/28/2014] [Indexed: 11/15/2022]
Abstract
An array with all-solid-state, potentiometric, miniaturized sensors for pH and potassium was developed to be introduced into the stomach or other sectors of the digestive tract by means of flexible endoscopy. These sensors perform continuous and simultaneous measurement of extracellular pH and potassium. This detection seeks to sense ischemia in the gastric mucosa inside the stomach, an event indicative of local microvascular perfusion and tissue oxygenation status. Our array is proposed as a medical tool to identify the occurrence of the ischemia after gastrointestinal or gastroesophageal anastomosis. The stability and feasibility of the miniaturized working and reference electrodes integrated in the array were studied under in vitro conditions, and the behavior of the potassium and pH ion-selective membranes were optimized to work under acidic gastric conditions with high concentrations of HCl. The array was tested in vivo in pigs to measure the ischemia produced by clamping the blood flow into the stomach. Our results indicate that ischemic and reperfusion states can be sensed in vivo and that information on tissue damage can be collected by this sensor array. The device described here provides a miniaturized, inexpensive, and mass producible sensor array for detecting local ischemia caused by unfavorable anastomotic perfusion and will thus contribute to preventing anastomotic leakage and failure caused by tissue necrosis.
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Affiliation(s)
- Islam Bogachan Tahirbegi
- Nanobioengineering Laboratory, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac, 10-12, Barcelona 08028, Spain; Department of Electronics, Barcelona University (UB), Martí i Franques, 1, Barcelona 08028, Spain
| | - Mònica Mir
- Nanobioengineering Laboratory, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac, 10-12, Barcelona 08028, Spain; Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Maria de Luna, 11, 50018 Zaragoza, Spain.
| | - Sebastian Schostek
- Steinbeis University, IHCI Institute, Dorfackerstr. 26, 72074 Tuebingen, Germany
| | - Marc Schurr
- Steinbeis University, IHCI Institute, Dorfackerstr. 26, 72074 Tuebingen, Germany
| | - Josep Samitier
- Nanobioengineering Laboratory, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac, 10-12, Barcelona 08028, Spain; Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Maria de Luna, 11, 50018 Zaragoza, Spain; Department of Electronics, Barcelona University (UB), Martí i Franques, 1, Barcelona 08028, Spain
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Tahirbegi IB, Mir M, Samitier J. Real-time monitoring of ischemia inside stomach. Biosens Bioelectron 2012; 40:323-8. [PMID: 22951532 DOI: 10.1016/j.bios.2012.07.071] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 07/03/2012] [Accepted: 07/13/2012] [Indexed: 10/28/2022]
Abstract
The low pH in the gastric juice of the stomach makes it difficult to fabricate stable and functional all-solid-state pH ISE sensors to sense ischemia, mainly because of anion interference and adhesion problem between the ISE membrane and the electrode surface. In this work, the adhesion of ISE membrane on solid surface at low pH was improved by modifying the surface with a conductive substrate containing hydrophilic and hydrophobic groups. This creates a stable and robust candidate for low pH applications. Moreover, anion interference problem at low pH was solved by integration of all-solid-state ISE and internal reference electrodes on an array. So, the same tendencies of anion interferences for all-solid-state ISE and all-solid-state reference electrodes cancel each other in differential potentiometric detection. The developed sensor presents a novel all-solid-state potentiometric, miniaturized and mass producible pH ISE sensor for detecting ischemia on the stomach tissue on an array designed for endoscopic applications.
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Affiliation(s)
- Islam Bogachan Tahirbegi
- Nanobioengineering Laboratory, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac, 10-12, Barcelona 08028, Spain
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Giouvanoudi AC, Spyrou NM. Epigastric electrical impedance for the quantitative determination of the gastric acidity. Physiol Meas 2008; 29:1305-17. [PMID: 18854603 DOI: 10.1088/0967-3334/29/11/006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Electrical impedance measurements have been used by scientists since the 1980s to investigate the gastric function. In this work, these measurements were carried out using the epigastrograph, a device generating alternating current of 32 kHz and injecting it in the gastric area of the human body with surface electrodes, located around the abdominal area. Although the method has been used for about three decades the physiological interpretation of these measurements is still under research. This work states that the electrical impedance measurements from the gastric area depend on the conductivity of the gastric lumen, due mainly to gastric acid secretions and to the conductivity and chemical form of the ingested meal. By choosing the proper test meal the gastric acidity in the empty, healthy stomach was also estimated. The estimated value is in accordance with the literature. The method is non-invasive, relatively inexpensive, simple to medical technologists and subjects, and involves no radiation risk. The method may form the basis for the development of a non-invasive gastric pH meter.
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Affiliation(s)
- A C Giouvanoudi
- STEF/Physics, Tech/cal Educational Institute, Thessaloniki, Greece.
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