Micromachined NH3 Gas Sensor with ppb-level Sensitivity Based on WO3 Nanoparticles Thinfilm

• DOI: 10.1016/j.proeng.2011.12.283
• Publication Date: 2012-01-09T19:53:22Z
• Authors: Dzung Viet Dao; Kyoji Shibuya; Tung Thanh Bui; Susumu Sugiyama
• Keywords: Diaphragm (acoustics); Tungsten trioxide

We present a micromachined gas sensor which can detect dilute NH3 at ppb (parts per billion) concentration based on chemoresistive effect of semiconducting tungsten trioxide (WO3). The structure consists poly-Si diaphragm-heater suspended four tiny beams, are connected to frame with overall chip size 1×1×0.3 mm3. Thanks the diaphragm-beam structure, power loss due thermal conduction decreases and uniformed temperature whole diaphragm is obtained. has been fabricated tested. Thermal efficiency heater was measured be 10 oC/mW. optimal working found around 300 oC, could in background wet air. nano-gap interdigitated electrodes improvement sensitivity also confirmed. Our estimation measurement results system noise showed limit-of-detection down 2.5 concentration.