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Xu L, Hu C, Huang Q, Jin K, Zhao P, Wang D, Hou W, Dong L, Hu S, Ma H. Trends and recent development of the microelectrode arrays (MEAs). Biosens Bioelectron 2021; 175:112854. [PMID: 33371989 DOI: 10.1016/j.bios.2020.112854] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/20/2020] [Accepted: 11/23/2020] [Indexed: 11/27/2022]
Abstract
In this paper, we reviewed the history of microelectrode arrays (MEAs), compared different microfabrication techniques applied to modern MEAs in terms of their material characters, device properties and application scenarios. Then we discussed the biocompatibility of different MEAs as well as corresponding strategy of improvement. At last, we analyzed the growing trend of MEAs' technical route, expected application of MEAs in the field of Electrical impedance tomography (EIT).
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Affiliation(s)
- Longqian Xu
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No.88 Keling Road, Suzhou, Jiangsu province, 215163, PR China
| | - Chenxuan Hu
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No.88 Keling Road, Suzhou, Jiangsu province, 215163, PR China
| | - Qi Huang
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No.88 Keling Road, Suzhou, Jiangsu province, 215163, PR China
| | - Kai Jin
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No.88 Keling Road, Suzhou, Jiangsu province, 215163, PR China; International Joint Research Center for Nanophotonics and Biophotonics, School of Science, Changchun University of Science and Technology, Changchun, Jilin province, 130022, PR China
| | - Ping Zhao
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No.88 Keling Road, Suzhou, Jiangsu province, 215163, PR China; International Joint Research Center for Nanophotonics and Biophotonics, School of Science, Changchun University of Science and Technology, Changchun, Jilin province, 130022, PR China
| | - Dongping Wang
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No.88 Keling Road, Suzhou, Jiangsu province, 215163, PR China
| | - Wei Hou
- Department of Radiation Oncology & Therapy, The First Hospital of Jilin University, NO.1 Xinmin Street, Changchun, Jilin province, 130021, PR China
| | - Lihua Dong
- Department of Radiation Oncology & Therapy, The First Hospital of Jilin University, NO.1 Xinmin Street, Changchun, Jilin province, 130021, PR China
| | - Siyi Hu
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No.88 Keling Road, Suzhou, Jiangsu province, 215163, PR China
| | - Hanbin Ma
- CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No.88 Keling Road, Suzhou, Jiangsu province, 215163, PR China.
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Khor JM, Tizzard A, Demosthenous A, Bayford R. Wearable sensors for patient-specific boundary shape estimation to improve the forward model for electrical impedance tomography (EIT) of neonatal lung function. Physiol Meas 2014; 35:1149-61. [DOI: 10.1088/0967-3334/35/6/1149] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Ahmed B. Study of peripheral circulation in non-pregnant, pregnant and pre-eclamptic women using applied potential tomography. Aust N Z J Obstet Gynaecol 2004; 44:322-7. [PMID: 15282004 DOI: 10.1111/j.1479-828x.2004.00240.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Profound changes are known to occur in the cardiovascular system during pregnancy, involving an increase in cardiac output and a fall in peripheral resistance. In some women these adaptations may be inappropriate and this may result in pregnancy-induced hypertension and pre-eclampsia. AIMS AND METHODS The aims of the study were to evaluate the relatively new, non-invasive technique of applied potential tomography (APT) in measurements of peripheral blood flow, to study peripheral blood flow in a sample of non-pregnant, pregnant and pre-eclamptic women, and to investigate whether the adaptive changes in the peripheral circulation are different in pre-eclampsia compared with normal pregnancy. Applied potential tomography was used to assess peripheral vascular reactivity, by monitoring fluid distribution in calf muscles during postural change. RESULTS The APT technique was able to detect peripheral vasoconstriction in response to an increase in intramural pressure brought about by passive lowering of the leg (peripheral mechanisms). The peripheral vasoconstriction response was found to be more prominent in woman with pre-eclampsia. CONCLUSIONS The presence of a local reflex in the lower limb had been postulated and the effect of this reflex on the peripheral circulation could be detected using APT, regardless of how it was initiated. In normal pregnant women this reflex was diminished when compared to non-pregnant women, which might contribute to the reduction in peripheral vascular resistance seen in normal pregnancy. This reflex was defective in pre-eclampsia and this lack of adaptation may be a local reflex contributing to the raised peripheral resistance, which in turn may be a factor in high blood pressure in pre-eclampsia.
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Abstract
Some evidence has been found that malignant breast tumors have lower electrical impedance than surrounding normal tissues. Although the separation of malignant tumors from benign lesions based on impedance measurements needs further investigation, electrical impedance could be used as an indicator for breast cancer detection. In this paper, we provide a systematic technical review of the existing electrical impedance techniques proposed for breast cancer detection, with an emphasis on noninvasive impedance imaging techniques. The electrical impedance of human breast tissue is first introduced, with tabulation of previous in vitro impedance measurement results on cancerous and normal breast tissues, and a brief description on the limited in vivo impedance measurements completed with invasive, or noninvasive, non-imaging techniques. A detailed review on noninvasive impedance imaging techniques for breast cancer detection, such as electrical impedance tomography (EIT) and electrical impedance mapping (EIM), is then presented. We suggest that for better breast cancer detection, an invasive impedance technique may be enhanced by combination with other cancer indicators. 3D EIT should be improved through collective efforts. EIM using a pair of electrode arrays is a viable method with great potential. Magnetic induction tomography and other magnetic induction based impedance imaging for breast cancer detection are promising and merit further exploration as well.
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Affiliation(s)
- Y Zou
- Department of Electrical and Computer Engineering, The George Washington University, 801 22nd Street NW, Washington, DC 20052, USA.
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Kunst PW, Vazquez de Anda G, Böhm SH, Faes TJ, Lachmann B, Postmus PE, de Vries PM. Monitoring of recruitment and derecruitment by electrical impedance tomography in a model of acute lung injury. Crit Care Med 2000; 28:3891-5. [PMID: 11153631 DOI: 10.1097/00003246-200012000-00025] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To evaluate a noninvasive system for obtaining information about alveolar recruitment and derecruitment in a model of acute lung injury. DESIGN Prospective experimental study. SETTING Animal research laboratory. SUBJECTS Nine anesthetized pigs. INTERVENTIONS Electrical impedance tomography measurements were performed. Electrical impedance tomography is an imaging technique that can register the ventilation-induced impedance changes in different parts of the lung. In nine anesthetized pigs, repeated lung lavages were performed until a PaO2 of <80 mm Hg was reached. Thereafter, the lungs were recruited according to two different recruitment protocols: the open lung approach and the open lung concept. Five time points for measurements were chosen: healthy (reference), lavage (atelectasis), recruitment, derecruitment, and maintain recruited (final). MEASUREMENTS AND MAIN RESULTS After lavage, there was a significant increase in the impedance ratio, defined as the ventilation-induced impedance changes of the anterior part of the lung divided by that of the posterior part (from 1.75 +/- 0.63 to 4.51 +/- 2.22; p < .05). The impedance ratio decreased significantly after performing the recruitment protocol (from 4.51 +/- 2.22 to 1.18 +/- 0.51). During both recruitment procedures, a steep increase in baseline impedance change was seen. Furthermore, during derecruitment, a decrease in the slope in baseline impedance change was seen in the posterior part of the lung, whereas the anterior part showed no change. CONCLUSION Electrical impedance tomography is a technique that can show impedance changes resembling recruitment and derecruitment of alveoli in the anterior and posterior parts of the lung. Therefore, electrical impedance tomography may help in determining the optimal mechanical ventilation in a patient with acute lung injury.
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Affiliation(s)
- P W Kunst
- Department of Pulmonary Medicine, Institute for Cardiovascular Research, Academic Hospital Vrije Universiteit, Amsterdam, The Netherlands
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Kunst PW, Böhm SH, Vazquez de Anda G, Amato MB, Lachmann B, Postmus PE, de Vries PM. Regional pressure volume curves by electrical impedance tomography in a model of acute lung injury. Crit Care Med 2000; 28:178-83. [PMID: 10667519 DOI: 10.1097/00003246-200001000-00029] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE A new noninvasive method, electrical impedance tomography (EIT), was used to make pressure-impedance (PI) curves in a lung lavage model of acute lung injury in pigs. The lower inflection point (LIP) and the upper deflection point (UDP) were determined from these curves and from the traditional pressure-volume (PV) curves to determine whether the PI curves resemble the traditional PV curves. Furthermore, regional differences in the mentioned determinants were investigated. DESIGN Prospective, experimental study. SETTING Animal research laboratory. INTERVENTIONS In nine anesthetized pigs, repeated lung lavage was performed until a Pao2 <80 torr was reached. Thereafter, an inspiratory PV curve was made using a constant flow of oxygen. During the intervention, EIT measurements were performed. MEASUREMENTS AND MAIN RESULTS In this study, the LIP(EIT) was within 2 cm H2O of the LIP(PV). Furthermore, it was possible to visualize regional PI curves by EIT. No significant difference was found between the LIP(PV) (21.3+/-3.0 cm H2O) and the LIP(EIT) of the total lung (21.5+/-3.0 cm H2O) or the anterior parts of the lung (21.5+/-2.9 cm H2O). A significantly higher LIP (29.5+/-4.9 cm H2O) was found in the posterior parts of the lung. A UDP(PV) could be found in three animals only, whereas in all animals a UDP(EIT) could be determined from the anterior part of the lung. CONCLUSIONS Using EIT, determination of LIP and UDP from the regional PI curves is possible. The obtained information from the regional PI curves may help in understanding alveolar recruitment. The use of this new bedside technique for clinical decision making remains to be examined.
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Affiliation(s)
- P W Kunst
- Department of Pulmonary Medicine, Institute for Cardiovascular Research, Academic Hospital Vrije Universiteit, Amsterdam, The Netherlands
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Kunst PW, Vonk Noordegraaf A, Raaijmakers E, Bakker J, Groeneveld AB, Postmus PE, de Vries PM. Electrical impedance tomography in the assessment of extravascular lung water in noncardiogenic acute respiratory failure. Chest 1999; 116:1695-702. [PMID: 10593797 DOI: 10.1378/chest.116.6.1695] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
STUDY OBJECTIVES To establish the value of electrical impedance tomography (EIT) in assessing pulmonary edema in noncardiogenic acute respiratory failure (ARF), as compared to the thermal dye double indicator dilution technique (TDD). DESIGN Prospective clinical study. SETTING ICU of a general hospital. PATIENTS Fourteen ARF patients. INTERVENTIONS In order to use the TDD to determine the amount of extravascular lung water (EVLW), a fiberoptic catheter was placed in the femoral artery. MEASUREMENTS AND MAIN RESULTS Fourteen consecutive ARF patients receiving mechanical ventilation were measured by EIT and TDD. EIT visualizes the impedance changes caused by the ventilation in two-dimensional image planes. An impedance ratio (IR) of the ventilation-induced impedance changes of a posterior and an anterior part of the lungs was used to indicate the amount of EVLW. For the 29 measurements in 14 patients, a significant correlation between EIT and TDD (r = 0. 85; p < 0.001) was found. The EIT reproducibility was good. The diagnostic value of the method was tested by receiver operator characteristic analysis, with 10 mL/kg of EVLW considered as the upper limit of normal. At a cutoff level of the IR of 0.64, the IR had a sensitivity of 93%, a specificity of 87%, and a positive predictive value of 87% for a supranormal amount of EVLW. Follow-up measurements were performed in 11 patients. A significant correlation was found between the changes in EVLW measured with EIT and TDD (r = 0.85; p < 0.005). CONCLUSION We conclude that EIT is a noninvasive technique for reasonably estimating the amount of EVLW in noncardiogenic ARF.
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Affiliation(s)
- P W Kunst
- Department of Pulmonary Medicine, Hospital Centre Apeldorn, The Netherlands
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Kunst PW, de Vries PM, Postmus PE, Bakker J. Evaluation of electrical impedance tomography in the measurement of PEEP-induced changes in lung volume. Chest 1999; 115:1102-6. [PMID: 10208215 DOI: 10.1378/chest.115.4.1102] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
STUDY OBJECTIVES A new noninvasive practical technique called electrical impedance tomography (EIT) was examined for the measurement of alveolar recruitment. DESIGN Prospective clinical study. SETTING ICU of a general hospital. PATIENTS Acute respiratory failure (ARF) patients. MEASUREMENTS The ventilation-induced impedance changes (VICs) of the nondependent and the dependent part of the lung were determined by EIT as a measure of tidal volume distribution. By the use of an impedance ratio (IR), defined as the VIC of the nondependent part of the lung divided by the VIC of the dependent part of the lung, the ventilation performances in both parts of the lung were compared to each other. RESULTS Between patients, the VIC of the nondependent part of the lung was significantly lower in the patients with a level of positive end-expiratory pressure (PEEP) of > 10 cm H2O than in patients with a PEEP of < 5 cm H2O (p < 0.05). A significantly lower IR (-/+ SD) was found in the group with PEEP of > 10 cm H2O than in the group with PEEP between 0 and 5 cm H2O (1.28+/-0.58 vs 2.99+/-1.24, respectively; p < 0.01). In individual patients, the VIC of the whole lung increased when the PEEP level was increased. The VICs of the nondependent part of the lung and of the dependent part of the lung showed significant increases at a PEEP of 10 cm H2O compared to a PEEP of 0 cm H2O (p < 0.05). Also the IR decreased in individual patients when the PEEP was increased; a significant decrease was found at 10 cm H2O compared to 0 cm H2O (1.67+/-1.24 vs 2.23+/-1.47, respectively; p < 0.05). CONCLUSIONS The decrease in IR indicates an increase in VIC in the dependent part of the lung above the nondependent part of the lung. The increase in VIC can be regarded as an increase in lung volume, implying alveolar recruitment in the dependent part of the lung. The same results also have been shown in earlier reports by CT scan. Since EIT is far more practical than CT scanning and also is a bedside method, EIT might help in the adjustment of ventilator settings in ARF patients.
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Affiliation(s)
- P W Kunst
- Department of Pulmonary Medicine, Institute for Cardiovascular Research, Academic Hospital Vrije Universiteit, Amsterdam, The Netherlands
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Kunst PW, Vonk Noordegraaf A, Hoekstra OS, Postmus PE, de Vries PM. Ventilation and perfusion imaging by electrical impedance tomography: a comparison with radionuclide scanning. Physiol Meas 1998; 19:481-90. [PMID: 9863674 DOI: 10.1088/0967-3334/19/4/003] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Electrical impedance tomography (EIT) is a technique that makes it possible to measure ventilation and pulmonary perfusion in a volume that approximates to a 2D plane. The possibility of using EIT for measuring the left-right division of ventilation and perfusion was compared with that of radionuclide imaging. Following routine ventilation (81mKr) and perfusion scanning (99mTc-MAA), EIT measurements were performed at the third and the sixth intercostal level in 14 patients with lung cancer. A correlation (r = 0.98, p < 0.005) between the left-right division for the ventilation measured with EIT and that with 81mKr was found. For the left-right division of pulmonary perfusion a correlation of 0.95 (p < 0.005) was found between the two methods. The reliability coefficient (RC) was calculated for estimating the left-right division with EIT. The RC for the ventilation measurements was 94% and 96% for the perfusion measurements. The correlation analysis for reproducibility of the EIT measurements was 0.95 (p < 0.001) for the ventilation and 0.93 (p < 0.001) for the perfusion measurements. In conclusion, EIT can be regarded as a promising technique to estimate the left-right division of pulmonary perfusion and ventilation.
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Affiliation(s)
- P W Kunst
- Department of Pulmonary Medicine, Academic Hospital Vrije Universiteit, Amsterdam, The Netherlands
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Kolehmainen V, Vauhkonen M, Karjalainen PA, Kaipio JP. Assessment of errors in static electrical impedance tomography with adjacent and trigonometric current patterns. Physiol Meas 1997; 18:289-303. [PMID: 9413863 DOI: 10.1088/0967-3334/18/4/003] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In electrical impedance tomography (EIT), difference imaging is often preferred over static imaging. This is because of the many unknowns in the forward modelling which make it difficult to obtain reliable absolute resistivity estimates. However, static imaging and absolute resistivity values are needed in some potential applications of EIT. In this paper we demonstrate by simulation the effects of different error components that are included in the reconstruction of static EIT images. All simulations are carried out in two dimensions with the so-called complete electrode model. Errors that are considered are the modelling error in the boundary shape of an object, errors in the electrode sizes and localizations and errors in the contact impedances under the electrodes. Results using both adjacent and trigonometric current patterns are given.
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Affiliation(s)
- V Kolehmainen
- Department of Applied Physics, University of Kuopio, Finland
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Jongschaap HC, Wytch R, Hutchison JM, Kulkarni V. Electrical impedance tomography: a review of current literature. Eur J Radiol 1994; 18:165-74. [PMID: 7957285 DOI: 10.1016/0720-048x(94)90329-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Electrical impedance tomography (EIT) is a relatively new imaging technique that has been developed during the past decade. The electrical properties of tissues are imaged by injecting small currents and measuring the resultant voltages. These voltages are then converted into a tomographic image using a reconstructing algorithm. The method has no known hazards and is relatively inexpensive. There are many possible clinical applications of this technique but apart from gastric emptying, most are still at the research stage as there are various technical and practical problems to be overcome. This paper describes the basic principles of EIT and reviews the English literature to try to assess its potential in clinical imaging.
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Dijkstra AM, Brown BH, Leathard AD, Harris ND, Barber DC, Edbrooke DL. Clinical applications of electrical impedance tomography. J Med Eng Technol 1993; 17:89-98. [PMID: 8263905 DOI: 10.3109/03091909309016213] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
This article is a preliminary review of the possible clinical applications of electrical impedance tomography (EIT). The applications to, for example, the central nervous, respiratory, cardiovascular and digestive systems are covered. It is concluded that the area of greatest potential application of EIT is monitoring cardiopulmonary function, but that studies on much larger groups of patients than have been carried out hitherto are required to fully assess the potential of EIT as a clinical tool.
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Affiliation(s)
- A M Dijkstra
- Department of Medical Physics and Clinical Engineering, Royal Hallamshire Hospital, Sheffield, UK
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Affiliation(s)
- R Pethig
- Institute of Molecular and Biomolecular Electronics, University of Wales, Bangor, Gwynedd, UK
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