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Eijkel J, Olthuis W, Bergveld P. An ISFET-based dipstick device for protein detection using the ion-step method. Biosens Bioelectron 1997. [DOI: 10.1016/s0956-5663(97)00054-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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27
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Eijkel J, Olthuis W, Kolev S, Bergveld P. Measuring Donnan-related phenomena using a solid-state ion sensor and a concentration-step method. J Memb Sci 1997. [DOI: 10.1016/s0376-7388(96)00281-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Eijkel JCT, Bosch C, Olthuis W, Bergveld P. Constructing a Proton Titration Curve from Ion-Step Measurements, Applied to a Membrane with Adsorbed Protein. J Colloid Interface Sci 1997; 187:148-58. [PMID: 9245324 DOI: 10.1006/jcis.1996.4689] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A new measuring method is described for obtaining a proton titration curve. The curve is obtained from a microporous composite membrane, consisting of polystyrene beads in an agarose matrix, with lysozyme molecules adsorbed to the bead surface. The membrane is incorporated into a sensor system by deposition on a silicon chip with a pH-sensitive ion-sensitive field effect transistor (ISFET) located in the middle of a Ag/AgCl electrode. The actual measurement is performed by creating a stepwise change in the salt concentration of the bathing electrolyte (the ion step) and measuring the ISFET potential versus the Ag/AgCl electrode. This potential shows a transient change in the ion step, which indicates a transient pH change in the membrane. This procedure is repeated at a series of pH values. Equations are presented to calculate the proton titration curve of the membrane from the amplitude and duration of the measured transients. Measurements show qualitative agreement between the curves obtained and equilibrium titration experiments on the same system.
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Bergveld P, van Hal R, Eijkel J. The remarkable similarity between the acid-base properties of ISFETs and proteins and the consequences for the design of ISFET biosensors. Biosens Bioelectron 1995. [DOI: 10.1016/0956-5663(95)96887-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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31
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van Kerkhof JC, Bergveld P, Schasfoort RB. The ISFET based heparin sensor with a monolayer of protamine as affinity ligand. Biosens Bioelectron 1995; 10:269-82. [PMID: 7755959 DOI: 10.1016/0956-5663(95)96846-q] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The ion-step measuring method was used to determine absolute heparin concentrations in PBS and blood plasma with a Ta2O5 ISFET on to which a monolayer of protamine had been immobilized. Heparin is a highly negatively charged polysaccharide, which is used clinically to delay the clotting of blood. Protamine acts as an affinity ligand for heparin. The response of the ISFET system on a step-wise increase in the electrolyte concentration (a so-called ion-step) is a transient change of the output voltage, which is related to the surface charge density of the ISFET gate oxide. After 2 mins of incubation in a plasma sample containing heparin, the amplitude of the transient ISFET response to an ion-step showed a linear relation to the heparin concentration. In blood plasma, heparin concentrations between 0.3 and 2.0 Units/ml could be determined with an accuracy of +/- 0.08 Units/ml. Heparin concentrations in different plasma samples of heparinized patients were determined and compared with the APTT. No direct relation was found between the APTT and the heparin concentration, but this result was not surprising.
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Cobben PL, Egberink RJ, Bomer JG, Bergveld P, Reinhoudt DN. Chemically modified field effect transistors: The effect of ion-pair association on the membrane potentials. J Electroanal Chem (Lausanne) 1994. [DOI: 10.1016/0022-0728(93)03114-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Olthuis W, Luo J, Bergveld P. Characterization of proteins by means of their buffer capacity, measured with an ISFET-based coulometric sensor—actuator system. Biosens Bioelectron 1994. [DOI: 10.1016/0956-5663(94)80073-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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34
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Cobben PL, Egberink RJ, Bomer JG, Schouwenaar R, Brzozka Z, Bos M, Bergveld P, Reinhoudt DN. Chemically modified ion-sensitive field-effect transistors: elimination of the liquid juction potential in a double sensor flow-injection analysis cell. Anal Chim Acta 1993. [DOI: 10.1016/0003-2670(93)80403-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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35
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Luo J, Olthuis W, Bergveld P, Bos M, van der Linden W. Modelling of coulometric sensor—actuator systems based on ISFETs with a porous actuator covering the gate. Anal Chim Acta 1993. [DOI: 10.1016/0003-2670(93)80600-p] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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36
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van Kerkhof J, Bergveld P, Schasfoort R. Development of an ISFET based heparin sensor using the ion-step measuring method. Biosens Bioelectron 1993. [DOI: 10.1016/0956-5663(93)80031-j] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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37
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Meier JH, Rutten WL, Zoutman AE, Boom HB, Bergveld P. Simulation of multipolar fiber selective neural stimulation using intrafascicular electrodes. IEEE Trans Biomed Eng 1992; 39:122-34. [PMID: 1612615 DOI: 10.1109/10.121643] [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: 12/27/2022]
Abstract
A realistic, quantitative model is presented for the excitation of myelinated nerve fibers by intrafascicular electrodes. It predicts the stimulatory regions of any configuration of any number of electrodes, positioned anywhere inside the fascicle. The model has two parts. First, the nerve fiber is represented by a lumped electrical network and its response to an arbitrary extracellular potential field is calculated. Second, assuming a cylindrical geometry of the nerve bundle and its surroundings, an analytical expression for this field is derived. With realistic parameters, the model is applied to two cases: monopolar stimulation by a single cathode and stimulation by a specific tripolar configuration. It is shown that tripolar stimulation has the better spatial selectivity. Also tripolar stimulation is less sensitive to the conductivity of the medium surrounding the nerve and yields a more natural recruitment order.
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Olthuis W, Bergveld P. On the charge storage and decay mechanism in silicon dioxide electrets. ACTA ACUST UNITED AC 1992. [DOI: 10.1109/14.155784] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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39
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Visch LL, Bergveld P, Lamprecht W, 's-Gravenmade EJ. pH measurements with an ion sensitive field effect transistor in the mouth of patients with xerostomia. IEEE Trans Biomed Eng 1991; 38:353-6. [PMID: 1855797 DOI: 10.1109/10.133230] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A transistor pH electrode (ion sensitive field effect transistor), placed in the upper dentures of eleven xerostomia patients and five healthy volunteers, was used to register pH changes in five-, six- and seven-day-old dental plaque. A mouth rinse with a 10% sucrose solution caused a pH fall of about three decades. A significant difference in duration of critical plaque pH was observed: in xerostomia patients, a 10% longer period of pH less than 5.7 was registered during 60 min following a sucrose rinse. Normal oral functions were not influenced by the denture with an integrated electrode. This method is usable for plaque pH registration in xerostomia patients.
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Abstract
During the last decennia many protein-related electrical phenomena have been studied and applied in a variety of measuring systems, from simple metal electrodes with adsorbed proteins to sophisticated systems with lipid bilayers. Many of the investigations concern the monitoring of immuno reactions. The basic underlying electrical effects of the observed phenomena are the protein modulated dielectric constant, conductivity, electrical potential, ion permeability and ion mobility. In this paper special attention is paid to the capacitive measurements with EIS systems as well as impedance and potential measurements with FET devices. The Donnan theory is treated and applied to the static ImmunoFET operation, explaining the relatively small effects which have been reported. Finally, an alternative approach is described in which the ImmunoFET is applied in a dynamic way, to circumvent the drawbacks of the static measurements.
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Schasfoort R, Bergveld P, Kooyman R, Greve J. The ion-step-induced response of membrane-coated ISFETs: theoretical description and experimental verification. Biosens Bioelectron 1991. [DOI: 10.1016/0956-5663(91)85045-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Kruise J, Bergveld P, Voorthuyzen JA. Chemical Sensors for In Vivo Monitoring: Fundamental Approaches and Promises of Available Technologies. ANAL LETT 1990. [DOI: 10.1080/00032719008052527] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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43
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Skowronska-Ptasinska M, van der Wal PD, van den Berg A, Bergveld P, Sudhölter EJ, Reinhoudt DN. Reference field effect transistors based on chemically modified ISFETs. Anal Chim Acta 1990. [DOI: 10.1016/s0003-2670(00)82762-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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44
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Abstract
A new method is presented for the detection of an immunological reaction taking place in a membrane, which covers the gate area of an ISFET. By stepwise changing the electrolyte concentration of the sample solution, a transient diffusion of ions through the membrane-protein layer occurs, resulting in a transient membrane potential, which is measured by the ISFET. The diffusion rate is determined by the immobile charge density in the amphoteric protein layer, which changes upon formation of antibody-antigen complexes. No membrane potential is induced at zero fixed charge density as occurs at a protein characteristic pH. Isoelectric points of embedded proteins can be determined by detecting the zero potential response. Up to now, the authors have studied the membrane adsorption of lysozyme, human serum albumin (HSA) and the immune reaction of HSA with the antibody anti-human serum albumin (alpha HSA). The influence of protein parameters on the amplitude of the transient can be described with an empirical equation. Assuming Langmuir behaviour, the protein concentration in the solution can well be correlated with the concentration in the membrane. This new detection method is unique concerning direct measurements of charge densities and isoelectric points of amphoteric macromolecules adsorbed in the membrane. The simple procedure of one incubation stage followed by one detection stage, without separate washing and labelling techniques, gives direct information about specific charge properties of the macromolecules to be studied.
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Sudhölter EJ, van der Wal PD, Skowronska-Ptasinska M, van den Berg A, Bergveld P, Reinhoudt DN. Modification of ISFETs by covalent anchoring of poly(hyroxyethyl methacrylate) hydrogel. Introduction of a thermodynamically defined semiconductor-sensing membrane interface. Anal Chim Acta 1990. [DOI: 10.1016/s0003-2670(00)82761-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Luo J, Olthuis W, van der Schoot B, Bergveld P, Bos M, van der Linden W. Modelling of the migration effect occurring at an ISFET-based coulometric sensor-actuator system. Anal Chim Acta 1990. [DOI: 10.1016/s0003-2670(00)83903-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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47
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Olthuis W, Luo J, Van der Schoot B, Bergveld P, Bos M, Van der Linden W. Modelling of non-steady-state concentration profiles at ISFET-based coulometric sensor—actuator systems. Anal Chim Acta 1990. [DOI: 10.1016/s0003-2670(00)85111-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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48
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Schasfoort R, Streekstra G, Bergveld P, Kooyman R, Greve J. Influence of an immunological precipitate on D.C. and A.C. behaviour of an isfet. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/0250-6874(89)87012-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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49
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Schasfoort R, Bergveld P, Bomer J, Kooyman R, Greve J. Modulation of the ISFET response by an immunological reaction. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/0250-6874(89)80041-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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50
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Olthuis W, Van Der Schoot B, Chavez F, Bergveld P. A dipstick sensor for coulometric acid-base titrations. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/0250-6874(89)80092-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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