A CMOS MEMS Gas Sensor Using Monolayer Protected Gold nanoClusters Coating On Three-Dimensional interdigitated Electrodes
Date Issued
2012
Date
2012
Author(s)
Chen, Yen-Cheng
Abstract
In this research, we developed a chemiresistive gas sensor for micro gas chromatography system. The sensing material, monolayer protected gold nano-cluster (MPC), was coated onto the three dimensional interdigitated electrodes (3D IDEs) of the sensor. The measuring principle of this sensitive material is based on the impedance variation corresponding to different gas concentrations. This chemiresistive sensor was realized by using CMOS-MEMS fabrication process is based on TSMC 0.35μm 2P4M (2 polysilicon 4 metal) process and post process. The device was completed after spreading the sensitive material MPC on its surface. The 3D IDEs are composed by the first and third layer of the metal on one side and the second and forth layer of the metal on the other side. Our 3D IDEs not only increased the sensing surface area at a given chip area but also decreased the gap distance between electrodes to 1μm. This reduced gap distance increased the sensitivity of the sensor as well as lowered the resistance of the deposited sensing material. In this research, the great linearity and sensitivity of the sensor were demonstrated with three compounds (Octane, Butanol, and Toluene) at different concentrations in the range of 30ppm to 5000ppm and manifested the good linearity and sensitivity. Our sensor with exceptional reliability was also demonstrated by a prolonged testing over three months with minimal drift.
Subjects
MEMS System
CMOS MEMS
Gas sensor
Monolayer Protected nano-Au Cluster
three-dimensional interdigitated electrodes
Type
thesis
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