• 한국산학기술학회논문지
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• 제5권1호
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• pp.83-86
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• 2004

고온용 마이크로 전자소자를 이용한 일산화탄소 가스센서를 개발하였다. 100-300℃의 영역에서 가스 감지 특성을 조사하였다. 센서의 가스 감도는 높고, 감지속도는 빠르고 센서는 재현성을 보여 주었다. Pt-SiC 및 Pt-SnO₂ 다이오드는 표준 반도체 공정을 이용하여 제작하였다. CO 가스 감지 특성은 정상상태 및 과도 상태의 조건아래에서 Ⅰ-Ⅴ 및 △Ⅰ-t법을 이용하여 CO 가스 농도와 온도의 함수로서 분석하였다. Pt-SnO₂촉매 층을 갖는 소자의 가스 감도가 Pt 게이트만으로 이루어진 소자보다 높았다. 실험 결과는 SnO₂층이 Pt막의 촉매 반응을 향상시키는 것을 보여주었다.

• 한국재료학회지
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• 제26권12호
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• pp.741-750
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• 2016

Nanofibers(NFs), because of their high surface area and nanosized grains, have appropriate morphologies for use in chemiresistive-type sensors for gas detection applications. In this study, a highly sensitive and selective CO gas sensing material based on Au-decorated $SnO_2$ NFs was fabricated by electrospinning. $SnO_2$ NFs were synthesized by electrospinning and subsequently decorated with various amounts of Au nanoparticles(NPs) by sputtering; this was followed by thermal annealing. Different characterizations showed the successful formation of Au-decorated $SnO_2$ NFs. Gas sensing tests were performed on the fabricated sensors, which showed bell-shaped sensing behavior with respect to the amount of Au decoration. The best CO sensing performance, with a response of ~20 for 10 ppm CO, was obtained at an optimized amount of Au (2.6 at.%). The interplay between Au and $SnO_2$ in terms of the electronic and chemical sensitization by Au NPs is responsible for the great improvement in the CO sensing capability of pure $SnO_2$ NFs, suggesting that Au-decorated $SnO_2$ NFs can be a promising material for fabricating highly sensitive and selective chemiresistive-type CO gas sensors.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1993-1997
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• 2012

Mg-doped ZnO one-dimensional (1D) nanostrutures were synthesized by using a thermal evaporation technique. The morphology, crystal structure, and sensing properties of the Mg-doped ZnO nanostructures functionalized with Pt to CO gas at $100^{\circ}C$ were examined. The diameters of the 1D nanostructures ranged from 80 to 120 nm and that the lengths were up to a few tens of micrometers. The gas sensors fabricated from multiple networked Mg-doped ZnO nanowires functionalized with Pt showed enhanced electrical response to CO gas. The responses of the nanowires were improved by approximately 70, 69, 111, and 81 times at CO concentrations of 10, 25, 50, and 100 ppm, respectively. Both the response and recovery times of the nanowire sensor for CO gas sensing were not nearly changed by Pt functionalization. It also appeared that the Mg doping concentration did not influence the sensing properties of ZnO nanowires as strongly as Pt-functionalization. In addition, the mechanism for the enhancement in the CO gas sensing properties of Mg-doped ZnO nanowires by Pt functionalization is discussed.

• 한국재료학회지
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• 제33권5호
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• pp.195-204
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• 2023

Micro-electronic gas sensor devices were developed for the detection of carbon monoxide (CO), nitrogen oxides (NO_x), ammonia (NH₃), and formaldehyde (HCHO), as well as binary mixed-gas systems. Four gas sensing materials for different target gases, Pd-SnO₂ for CO, In₂O₃ for NO_x, Ru-WO₃ for NH₃, and SnO₂-ZnO for HCHO, were synthesized using a sol-gel method, and sensor devices were then fabricated using a micro sensor platform. The gas sensing behavior and sensor response to the gas mixture were examined for six mixed gas systems using the experimental data in MEMS gas sensor arrays in sole gases and their mixtures. The gas sensing behavior with the mixed gas system suggests that specific adsorption and selective activation of the adsorption sites might occur in gas mixtures, and allow selectivity for the adsorption of a particular gas. The careful pattern recognition of sensing data obtained by the sensor array made it possible to distinguish a gas species from a gas mixture and to measure its concentration.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.369-370
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• 2005

LTCC (Low Temperature Cofired Ceramic) technology is one of technologies which can realize SIP (System-In-a-Package). In this paper realization of gas sensor using LTCC technology was described. In the conventional gas sensor structure, wire bonding method is generally used as an interconnection method whereas in the LTCC sensor structure, via was used for the interconnection. As sensing materials, $SnO_2$ was adopted. The effect of frit glass portion on the adhesion of the sensing material to the LTCC substrate and the electrical conductivity of the sensing material were analyzed. AgPd, PdO, Pt was added to the sensing material as an additive for improving the gas sensitivity and electrical conductivity and the effect of the amount of additives in the sensing material on the electrical conductivity was investigated. The effect of the amount of frit glass in the termination on the sensor performance, especially mechanical integrity, was considered and the crack initiation and propagation in the boundary between the sensing material and the termination was studied.

• 센서학회지
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• 제19권5호
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• pp.385-390
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• 2010

CO sensing thick film gas sensors using $Co_3O_4$ powders prepared by hydrothermal reaction method, were fabricated, and their structural, electrical and CO gas sensing properties were investigated. The specific surface area of the $Co_3O_4$ powders obtained from BET analysis was about 79.0 $m^2/g$. XRD and SEM results show that the thick films heat-treated at $500^{\circ}C$ for 30 min after screen printing had the preferred orientation of (311) direction and the crystalline size was calculated to 221 $\AA$. The maximum activation energy obtained from the temperature-resistance characteristics was 3.11 eV in the temperature range of $290^{\circ}C$ to $310^{\circ}C$. The sensitivity to 1,000 ppm CO was about 150 %. The specific surface area, crystalline size, and maximum activation energy were increased significantly and the sensitivity for CO gas was improved largely.

• 한국재료학회지
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• 제20권5호
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• pp.235-240
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• 2010

We investigated the carbon monoxide (CO) gas-sensing properties of nanostructured Al-doped zinc oxide thin films deposited on self-assembled Au nanodots (ZnO/Au thin films). The Al-doped ZnO thin film was deposited onto the structure by rf sputtering, resulting in a gas-sensing element comprising a ZnO-based active layer with an embedded Pt/Ti electrode covered by the self-assembled Au nanodots. Prior to the growth of the active ZnO layer, the Au nanodots were formed via annealing a thin Au layer with a thickness of 2 nm at a moderate temperature of $500^{\circ}C$. It was found that the ZnO/Au nanostructured thin film gas sensors showed a high maximum sensitivity to CO gas at $250^{\circ}C$ and a low CO detection limit of 5 ppm in dry air. Furthermore, the ZnO/Au thin film CO gas sensors exhibited fast response and recovery behaviors. The observed excellent CO gas-sensing properties of the nanostructured ZnO/Au thin films can be ascribed to the Au nanodots, acting as both a nucleation layer for the formation of the ZnO nanostructure and a catalyst in the CO surface reaction. These results suggest that the ZnO thin films deposited on self-assembled Au nanodots are promising for practical high-performance CO gas sensors.

• 한국재료학회지
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• 제19권11호
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• pp.607-612
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• 2009

We investigated the effects of Co doping on the NO gas sensing characteristics of ZnO-carbon nanotube (ZnO-CNT) layered composites fabricated by coaxial coating of single-walled CNTs with ZnO using pulsed laser deposition. Structural examinations clearly confirmed a distinct nanostructure of the CNTs coated with ZnO nanoparticles of an average diameter as small as 10 nm and showed little influence of doping 1 at.% Co into ZnO on the morphology of the ZnO-CNT composites. It was found from the gas sensing measurements that 1 at.% Co doping into ZnO gave rise to a significant improvement in the response of the ZnO-CNT composite sensor to NO gas exposure. In particular, the Co-doped ZnO-CNT composite sensor shows a highly sensitive and fast response to NO gas at relatively low temperatures and even at low NO concentrations. The observed significant improvement of the NO gas sensing properties is attributed to an increase in the specific surface area and the role as a catalyst of the doped Co elements. These results suggest that Co-doped ZnOCNT composites are suitable for use as practical high-performance NO gas sensors.

• 센서학회지
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• 제20권6호
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• pp.428-433
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• 2011

We report on the building of a micro sensor array based on typical semiconductor fabrication processes aimed at monitoring selectively a specific gas in ambient of other gases. Chemical sensors can be applied for an electronic nose and/or robots using this technique. Microsensor array was fabricated on the same chip using 0.6${\mu}m$ CMOS technology, and unique gas sensing patterns were obtained by principal component analysis from the array. $SnO_2$/Pt sensor for CO gas showed a high selectivity to buthane gas and humidity. $SnO_2$ sensor for hydrogen gas, however, showed a low selectivity to CO and buthane gas. We can obtain more distinguishable patterns that provide the small sensing deviation(the high seletivity) toward a given analyte in the response space than in the chemical space through the specific parameterization of raw data for chemical image formation.

• 한국세라믹학회지
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• 제40권12호
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• pp.1177-1182
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• 2003

BaTiO$_3$ 분말에 흑연 분말을 첨가하여 BaTiO$_3$계 가스센서용 다공성 감지물을 제조하였으며, 이 감지물의 결정구조와 미세구조를 연구하였다. 이 감지물 소성체는 정방정 perovskite 결정구조를 가지고 있었다 흑연 분말의 첨가량이 증가함에 따라 소성체의 기공도가 증가하였다. 이것은 소성 시 흑연 분말과 산소가 발열반응하여 CO 및 $CO_2$ 가스를 생성하고, 이 가스가 휘발하였기 때문이라고 생각된다. 제조한 BaTiO$_3$계 소성체는 대기에서 측정한 저항과 CO 가스에서 측정한 저항이 고온( >∼20$0^{\circ}C$)에서 큰 차이를 나타내고 있으며 온도가 증가함에 따라 차이가 커짐을 관찰하였다. 소성체 기공도의 증가에 따른 반응 site의 증가로 인하여 소성체의 표면흡착기인 $O_2$$^{-}$와 CO 가스의 반응과, 소성체에 있는 $O^{-}$와 CO 가스의 반응이 활발하기 때문에 CO 가스의 민감도가 크게 증가하였다. 본 연구에서 제조된 다공성 BaTiO$_3$계 세라믹스는 CO 가스센서의 감지물 재료로써 유망하다고 생각된다.