title: An acetone microsensor with a ring oscillator circuit fabricated using the commercial 0.18 μm CMOS process.
abstract: This study investigates the fabrication and characterization of an acetone microsensor with a ring oscillator circuit using the commercial 0.18 μm complementary metal oxide semiconductor (CMOS) process. The acetone microsensor contains a sensitive material, interdigitated electrodes and a polysilicon heater. The sensitive material is α-Fe2O3 synthesized by the hydrothermal method. The sensor requires a post-process to remove the sacrificial oxide layer between the interdigitated electrodes and to coat the α-Fe2O3 on the electrodes. When the sensitive material adsorbs acetone vapor, the sensor produces a change in capacitance. The ring oscillator circuit converts the capacitance of the sensor into the oscillation frequency output. The experimental results show that the output frequency of the acetone sensor changes from 128 to 100 MHz as the acetone concentration increases 1 to 70 ppm.
authors.affiliation: Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan. d099061005@mail.nchu.edu.tw.
authors.forename: Ming-Zhi
authors.initials: MZ
authors.lastname: Yang
authors.affiliation: Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan. cldai@dragon.nchu.edu.tw.
authors.forename: Ching-Liang
authors.initials: CL
authors.lastname: Dai
authors.affiliation: Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung 811, Taiwan 320, Taiwan. pjshih@nuk.edu.tw.
authors.forename: Po-Jen
authors.initials: PJ
authors.lastname: Shih
mesh_terms: D000096:Acetone / Q000737:chemistry*; D025802:Electric Capacitance; D004566:Electrodes; D004867:Equipment Design / Q000295:instrumentation*; D005290:Ferric Compounds / Q000737:chemistry; D005740:Gases / Q000737:chemistry; D010087:Oxides / Q000737:chemistry*; D012666:Semiconductors
chemical_list: D005290:Ferric Compounds; D005740:Gases; D010087:Oxides; D000096:Acetone