Improvements in the responses of
semiconductor gas sensors and reductions in their detection limits toward
volatile organic compounds (VOCs) are required in order to facilitate the simple detection of diseases, such as
cancer, through human-breath analysis. In this study, we introduce a heater-switching, pulse-driven, micro gas sensor composed of a microheater and a sensor
electrode fabricated with Pd-SnO2-clustered nanoparticles as the
sensing material. The sensor was repeatedly heated and allowed to cool by the application of voltage to the microheater; the VOC
gases penetrate into the interior of the sensing layer during its unheated state. Consequently, the utility factor of the pulse-driven sensor was greater than that of a conventional, continuously heated sensor. As a result, the response of the sensor to
toluene was enhanced; indeed, the sensor responded to
toluene at levels of 1 ppb. In addition, according to the relationship between its response and concentration of
toluene, the pulse-driven sensor in this report can detect
toluene at concentrations of 200 ppt and even lower. Therefore, the combination of a pulse-driven microheater and a suitable material designed to detect
toluene resulted in improved sensor response, and facilitated ppt-level
toluene detection. This sensor may play a key role in the development of medical diagnoses based on human breath.