Browsing by Author "Chao, Shuchi"

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A Flexible pH-Sensing Structure Using WO3/IrO2 Junction with Al2O3 Encapsulation Layer
(2013)
Kuo, Li-Min
;
Chen, Kuan-Neng
;
Chuang, Yi-Lin
;
Chao, Shuchi
;
電子物理學系
A diode-like current-voltage characteristic in response to hydrogen-ions based on a WO3/IrO2 diode coated with a membrane-like Al2O3 is reported. Microsensors fabricated with the oxides (IrO2 and WO3) will suffer from interference errors in pH-measurements due to their strong responses to environmental redox species. With ionic-conductive and insulation properties, the membrane can mediate the transport of released protons and block the electrons from redox species in solutions. Invoking proton-electron double injection, H+ and e(-) produce redox reactions, which control the conductivity and preserve the continuity of currents across the interface with a good sensitivity (0.168 mu A/pH) between pH = 2 to 12. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.004303ssl] All rights reserved.
A new hybrid method for H2S-sensitive devices using WO3-based film and ACF interconnect
(2013-07-01)
Kuo, Li Min
;
Shih, Yu-Tai
;
Wu, Cen-Shawn
;
Lin, Yu-Chi
;
Chao, Shuchi
A new hybrid integration method has been reported for process simplification of conventional metal-oxide sensors with a gold (Au) dopant-like catalyst during hydrogen sulfide (H2S) gas detections at room temperature. Different from conventional fabrications, an anisotropic conduction film (ACF) followed by a sputtered tungsten oxide (WO3) film tapped on Cu electrodes has been utilized in consumer applications. The process steps were reduced without compromising electrical performances. The treated ACF with a thin WO3 film, coated across two closely spaced microelectrodes is employed as the H2S solid-state sensor at room temperature. Apart from exhibiting good interconnects as conductive bumps, Au dopant-like catalyst within ACF will also produce a lower barrier between the bands of electronics, and therefore improve the electrical conductivity significantly. Our integration method offers a number of merits, including high sensitivity to the reference gas, lead-free bonding connection, low-temperature fabrication, high throughput and less fabrication time.
A precise pH microsensor using RF-sputtering IrO2 and Ta2O5 films on Pt-electrode
(2014-03-01)
Kuo, Li-Min
;
Chou, Yi-Chia
;
Chen, Kuan-Neng
;
Lu, Chien-Chia
;
Chao, Shuchi
In this study, an easily implemented surface modification scheme is reported employing Ta2O5 membrane which covers IrO2 electrode in response to H+ and eliminating redox species interference. Evidence shows that H+ can pass through Ta2O5 films and react with IrO2/Pt electrodes due to proton-electron double injection. A Ta2O5 membrane, an ionic conductor with an insulating property, blocks the transport of electrons generated from oxygen perturbation in the solution. The conduction of both electrons and protons preserve the current continuity across the interface. Owing to proton-electron double injection, IrO2 will be reduced to Ir(OH)(3) during pH detection. The [IrO2]/[Ir(OH)(3)] will remain constant and therefore the Nernstian electrode potential performs stably as a function of pH (-59.447 to -59.504 mV/pH, 2< pH <13). In addition, the proposed pH microsensor displayed high ion selectivity with respect to K+, Na+, and Li+, with log K-H,K-M values (similar to-12.4) and has a working lifetime over one week. (C) 2013 Elsevier B.V. All rights reserved.
Electrolyte-Free, H2S-Sensitive Microdiode Using a WO3/IrO2 Junction and Au Catalyst
(2013-10-01)
Kuo, Li Min
;
Shih, Yu-Tai
;
Wu, Cen-Shawn
;
Su, Chin-Yu
;
Chao, Shuchi
The H2S gas sensing performance based on a WO3/IrO2 diode assisted by gold (Au)-catalyst is investigated. Intermolecular force, similar to Van Der Waal interaction, initiates interstitial-water in IrO2 film to be H+-dipoled permanently. H+ and e(-) produce reversible redox reactions, which control conductivity by utilizing proton-electron double injection. As a result of the catalysis contributed from Au dopant-like particles distributed uniformly on the microdiode bulk surface, the barrier height between the surface of WO3-based microdiode and the reference gas molecules will be decreased in response upon exposure to H2S gas and therefore improve conductometric change significantly. The preliminary dc analysis of the microdiode has revealed repeatable and durable results. Such a microdiode can work stably for a long time without significant signal deterioration.