20.3 A 4.0×3.7×1.0mm³-MEMS CMOS Integrated E-Nose with Embedded 4×Gas Sensors, a Temperature Sensor and a Relative Humidity Sensor

Abstract

An Electronic Nose (F-Nose). capable of recognizing various odors and flavors, will add essential functions to Al robots [1], which traditional physical sensors such as cameras cannot provide. To date, a miniaturized E-Nose, as a chemical sensor, that is capable of sensing multiple gases below ppm-level, still remains a challenge. As a miniaturized but highly sensitive gas sensor platform, chemically coated resonators such as beam resonator [2], Surface Acoustic Wave (SAW) [4], and Film Bulk Acoustic Resonator (FBAR) [5] or integrated metal nanosheets with catalytic reaction [3] have been reported so far. However, none of them demonstrates 1 ppm sensitivity in response to a change in temperature (TEMP) and relative humidity (RH). This work advances the state-of-the-art by integrating a TEMP sensor, an RH sensor within a 4.0×3.7×1.0mm3 package allowing TEMP (15°C~ 35°C) and RH (30 ~ 70%RH) regulated sensing (ppm-level accuracy) of up to 4 different gases at once. With the help of dedicated AFE, chemically-tuned 2.5GHz Shear Horizontal (SH) SAW sensor responds to a 1 ppm Toluene gas within 200 seconds with a limit of detection (LoD) of 0.02ppm.