• Journal of Sensor Science and Technology
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• v.21 no.2
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• pp.90-95
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• 2012

This paper describes the development of a glucose biosensor based on ion sensitive field effect transistor(ISFET) with a palladium(Pd) modified ion sensing membrane. By adopting Pd as a hydrogen sensitive layer and integrating a screen-printed reference electrode, the sensitivity and stability were considerably improved due to the high permeability and selectivity of the Pd hydrogen selective membrane. This paper suggests a new approach for realizing portable and highly sensitive glucose sensors for diagnosing and treating diabetes mellitus.

• Transactions on Semiconductor Engineering
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• v.1 no.1
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• pp.9-13
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• 2023

An AlGaN/GaN heterojunction-based hydrogen sensor with SnO₂ nanoparticles/Pd catalyst layer was fabricated for room-temperature hydrogen detection. The fabricated sensor exhibited unstable drift in standby current when it was operated at room temperature. The instability in the sensing signal was dramatically improved when the sensor was operated under UV illumination.

• Journal of Sensor Science and Technology
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• v.16 no.1
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• pp.7-10
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• 2007

A thick film catalytic gas sensors which can be operated at $142^{\circ}C$ in presence of ultra violet-light emitting diode has been developed to measure hydrogen concentration in 0-5 % range. The sensing material as a combustion catalyst consists of $TiO_{2}$ (5 wt%) and Pd/Pt (20 wt%) supported on $Al_{2}O_{3}$ powder and the reference material to compensate the heat capacity of it in a bridge circuit was an catalyst free $Al_{2}O_{3}$ powder. Platinum heater and sensor materials were formed on the alumina plate by screen printing method and heat treatment. The effect of UV radiation in the presence of photo catalyst $TiO_{2}$ on the sensor sensitivity, response and recovery time has been investigated. The reduction of operating temperature from $192^{\circ}C$ to $142^{\circ}C$ for hydrogen gas sensing property in presence of UV radiation is attributed to the hydroxy radical and superoxide which was formed at the surface of $TiO_{2}$ under UV radiation.

• Journal of the Korean institute of surface engineering
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• v.56 no.6
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• pp.420-426
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• 2023

We prepared a highly sensitive hydrogen (H₂) sensor based on Indium oxides (In₂O₃) porous nanoparticles (NPs) loaded with Platinum (Pt) nanoparticle in the range of 1.6~5.7 at.%. In₂O₃ NPs were fabricated by microwave irradiation method, and decorations of Pt nanoparticles were performed by electroless plating on In₂O₃ NPs. Crystal structures, morphologies, and chemical information on Pt-loaded In₂O₃ NPs were characterized by grazing-incident X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, respectively. The effect of the Pt nanoparticles on the H₂-sensing performance of In₂O₃ NPs was investigated over a low concentration range of 5 ppm of H₂ at 150-300 ℃ working temperatures. The results showed that the H₂ response greatly increased with decreasing sensing temperature. The H₂ response of Pt loaded porous In₂O₃ NPs is higher than that of pristine In₂O₃ NPs. H₂ gas selectivity and high sensitivity was explained by the extension of the electron depletion layer and catalytic effect. Pt loaded porous In₂O₃ NPs sensor can be a robust manner for achieving enhanced gas selectivity and sensitivity for the detection of H₂.

• Journal of Sensor Science and Technology
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• v.5 no.4
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• pp.41-46
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• 1996

The Pd/Pt gate MISFET type hydrogen sensors, for detecting dissolved hydrogen gas in the transformer oil, were fabricated and their characteristics were investigated. These sensors including diffused resister heater and temperature monitoring diode were fabricated on the same chip by a conventional silicon process technique. The differential pair plays a role in minimizing the intrinsic voltage drift of the MISFET. To avoid the drift of the sensors induced by the hydrogen, the gate insulators of both FETs were constructed with double layers of silicon dioxide and silicon nitride. In order to eliminate the blister formation on the surface of the hydrogen sensing gate metal, Pt and Pd double metal layers were deposited on the gate insulator. The hydrogen response of the Pd/Pt gate MISFET suggests that the proposed sensor can detect the dissolved hydrogen in transformer oil with 40mV/10ppm of sensitivity and 0.14mV/day of stability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.91-91
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• 2009

In the past decade, Pd based thin films have been studied far hydrogen gas sensors due to their high possibility for energy industry and environmental applications. In this work, we report a navel method to fabricate highly sensitive hydrogen gas sensors based on PdO thin films. The films were deposited on Si substrates in Ar and $O_2$ ambient using reactive sputtering system. A semiconductor process has been utilized to fabricate PdO films with t=40nm. We observed the resistance changes of the PdO films with various $H_2$ concentrations. It was found that the electrical properties of the thin films depend on the composition of oxygen. The sensitivity is defined as $S\;=\;(R_0-R)/R{\times}100%$, where R and $R_0$ are the resistances in the presence of exposing the hydrogen gas and air, respectively. The sensitivity of the thin films was found to be as high as about 95%. After exposing to hydrogen gas, we discovered that the nano-sized cracks formed on the surface of the PdO thin films. The nano-cracks formed in deoxidized PdO thin films were known by playing a key role to reduce more than 4 times the response time of absorption. Our results illustrate that the deoxidized PdO thin films can be used as hydrogen sensors.

• Korean Journal of Metals and Materials
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• v.48 no.4
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• pp.347-352
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• 2010

This study reports a novel method off abricating highly sensitive hydrogen gas sensors based on PdO thin films. The PdO thin films with a thickness of 40 nm were deposited on Si substrates under Ar and $O_2$ ambient conditions using a reactive de magnetron sputtering system. Considerable changes in the resistance of the palladium oxide thin films were observed when they were initially exposed to hydrogen gas, as a result of the reduction process. The sensitivity of the PdO thin films was found to be as high as 90%. After the thin films were exposed to hydrogen gas, the nano-sized cracks were discovered to have formed on the surface of the PdO thin films. These types of nano-cracks that formed on the deoxidized PdO thin films are known to play a key role incausing a four-fold reduction of the response time of the absorption process. The results of this study demonstrate that deoxidized PdO thin films can be applied for use in the creation of high-sensitivity hydrogen sensors.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2197-2202
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• 2014

In this paper, we report on an investigation of highly sensitive sensing performance of a hydrogen sensor composed of palladium (Pd) nanowires. The Pd nanowires have been grown by electrodeposition into nanochannels and liberated from the anodic aluminum oxide (AAO) template by dissolving in an aqueous solution of NaOH. A combination of photo-lithography, electron beam lithography and a lift-off process has been utilized to fabricate the sensor using the Pd nanowire. The hydrogen concentrations for 2% and 0.1% were obtained from the sensitivities (${\Delta}R/R$) for 1.92% and 0.18%, respectively. The resistance of the Pd nanowires depends on absorption and desorption of hydrogen. Therefore, we expect that the Pd nanowires can be applicable for detecting highly sensitive hydrogen gas at room temperature.

• Journal of the Korean Society of Safety
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• v.1 no.1
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• pp.21-26
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• 1986

Gas sensing materials for detecting inflammable gas such as alcohol, propane, acetic acid, carbon monoxide, hydrogen were developed by utiliting $MgO-Cr_2O_3-TiO_2$ system. Between 30$0^{\circ}C$ and 50$0^{\circ}C$, reversible chemisorption becomes dominant and the electrical canduction of P-type semiconductive with the gas chemisorption. The ceramic sensor exhibits a high sensitivity to particular reducing gas such as alcohol, whereas propane and butane have little effect on the resistivity. The time response of adsorption is estimated to be about 20 sec. On the other hand, the desorption process, which corresponds to oxidation due to oxygen adsorption, take more than 60 sec. Thus the ceramic sensor can be used as a alcohol sensor in an ambient aunosphere. As the oxygen concentration is increased from 0.1 to 10 precent($10^3-10^6ppm$), the resistance decreases rapidly but stabilizes at higher concentration.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.434-434
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• 2011

Electrochemical method have been employed in this work to modify the chemical vapour deposited nitrogen doped hydrogen amorphous diamond-like carbon (N-DLC) film to fabricate nickel and copper nano particle modified N-DLC electrodes. The electrochemical behaviour of the metal nano particle modified N-DLC electrodes have been characterized at the presence of glucose in electrolyte. Meanwhile, the N-DLC film structure and the morphology of metal nano particles on the N-DLC surface have been investigated using micro-Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. The nickel nano particle modified N-DLC electrode exhibits a high catalytic activity and low background current, while the advantage of copper modified N-DLC electrode is drawn back by copper oxidizations at anodic potentials. The results show that metal nano particle modification of N-DLC surface could be a promising method for controlling the electrochemical properties of N-DLC electrodes.