Fully Integrated Photoacoustic NO2 Sensor for Sub-ppb Level Measurement

Sub-ppm multi-gas photoacoustic sensor.

A photoacoustic multi-gas sensor using tuneable laser diodes in the near-infrared region is reported. An optimized resonant configuration based on an acoustic longitudinal mode is described. Automatic tracking of the acoustic resonance frequency using a piezo-electric transducer and a servo electronics is demonstrated. Water vapour, methane and hydrogen chloride have been measured at sub-ppm le...

Room temperature, ppb-level NO2 gas sensing of multiple-networked ZnSe nanowire sensors under UV illumination

Reports of the gas sensing properties of ZnSe are few, presumably because of the decomposition and oxidation of ZnSe at high temperatures. In this study, ZnSe nanowires were synthesized by the thermal evaporation of ZnSe powders and the sensing performance of multiple-networked ZnSe nanowire sensors toward NO2 gas was examined. The results showed that ZnSe might be a promising gas sensor materi...

Photoacoustic Measurements of Agriculturally Interesting Gases and Detection of C2H4 below the PPB Level

A Fully Integrated Shear Stress Sensor

A fully integrated shear-stress sensor has been developed using a post-IC process that is added onto 4′′ foundry-processed CMOS wafers. The shear-stress sensor uses a gate-polysilicon hot-wire as the sensing element that sits on a freestanding Parylene diaphragm suspended over a cavity. A special Parylene vacuum sealing and etchback process is used to achieve better thermal isolation and overal...

A fully integrated wafer-scale sub-mm FBAR-based wireless mass sensor

A wireless sub-mm FBAR-based mass sensor fully integrated in a hermetic package is demonstrated. We propose a wafer-scale commercially viable manufacturing process for the integration of the sensor and the interface circuitry. The drift in frequency of the FBAR sensor due to temperature, aging and stress is reduced by a factor of 10 through an integrated differential measurement. The sensor ach...