• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.6
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• pp.28-33
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• 1985

ISFETS for physiological applications have been developed using the techniques for integrated circuit fabrication. The silicon nitride layer was used as a H+ sensing membrane. However, K+, Na+ and Ca++ sensing ISFETS were fabricated by forming tach specification sensing membranes over the silicon nitride gate insulator. The sensitivities of the fabricated devices were very good. The typical values of measured sentivities were iEmV/pH, 42mv1, pH,5 gmV/pNa and 28mv1p0a. However, the selectivity and stability should be somewhat improved for practical physiological uses with good reliability. The response times were, less than one second, short enough for the practical uses in physiological applications.

• Journal of Sensor Science and Technology
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• v.2 no.1
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• pp.41-48
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• 1993

An ISFET urea sensor was fabricated by immobilizing the urease using polyurethane on the $H^{+}$ sensing $Si_{3}N_{4}$ thin film of pH-ISFET. The sensor could determine the urea concentration $1{\sim}50$ mg/dl with fast response of $3{\sim}5$ min. and good repeatability. For its application to clinical analysis, the results of the urea measurements in blood plasma using ISFET urea sensor were compared with these of conventional Urease-Indophenol method.

• ETRI Journal
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• v.31 no.2
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• pp.243-245
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• 2009

A novel ultra-low-power readout circuit for a pH-sensitive ion-sensitive field-effect transistor (ISFET) is proposed. It uses an ISFET/reference FET (REFET) differential pair operating in weak-inversion and a simple current-mode metal-oxide semiconductor FET (MOSFET) translinear circuit. Simulation results verify that the circuit operates with excellent common-mode rejection ability and good linearity for a single pH range from 4 to 10, while only 4 nA is drawn from a single 1 V supply voltage.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.486-489
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• 1987

For longterm conservation of the $Si_3N_4$ gate pH-ISFET, characteristics of ISFET surface treatment with HF and surface coating with paraffin wax were investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.103-104
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• 2012

• Journal of Sensor Science and Technology
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• v.4 no.4
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• pp.55-61
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• 1995

A new ISFET array chip, based on detection of the threshold voltages of ISFETs by using an adjustable input, was designed. The chip includes 240 pH-ISFETs and circuitry such as comparators, a decoder and register. The chip has increased reliability, improved accuracy, digital output capability and the possibility of multi sensor implementation. To fabricate the chip, an extended CMOS process was devised and implemented.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.11
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• pp.1335-1341
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• 1988

A pH-ISEFET microprobe for in vivo measurements has been fabricated by combining ISFET (SL-IIS) chip and capillary thin film reference electrode. A two-step TCE oxidation for the gate oxide layer and multilayer encapsulation using silicone rubber and epoxy were specially used for the improvement of the stability and temperature dependence of the ISFET's. The measured sensitivit, response time and temperature dependence of the pH-ISFET microprobes are 50 mV/pH, less than one second, and - 0.01 pH/$^{\circ}$ , respectively. By operating continuously more than 40 days, a long term stability of 0.016 pH/day is obtained. The result of pH monitoring of femoral arterial blood in a rabbit is fairly good agreement with the value of blood gas analysis.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.1
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• pp.46-51
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• 1991

The new signal process circuit using ISFETs as two input devices of a MOS differential amplifier stage for application to a ISFET biosensor was developed and its operational characteristics simulated. For a single chip integration of ISFETs, developed signal process circuit and metal reference electrode, serial studies including process development and chip layout was carried out.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.4
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• pp.58-63
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• 1992

Photolithography techniques were applied for immobilization of GOD membrane on the pH-ISFET with photo-sensitive polymers to realize ISEFT glucose sensor. This IC technology-compatible glucose sensor showed good sensing characteristics in the wide range of 10-1000 mg/dl glucose concentrations.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.301-304
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• 1988

A pH-meter has been newly developed by using on ISFET as the ion sensing element. The performance characteristics of the developed pH-meter have been investigated and confirmed to be used practically. The stable operation and the temperature compensation were stressed in this study.