title: A miniature electronic nose system based on an MWNT-polymer microsensor array and a low-power signal-processing chip.
abstract: This article introduces a power-efficient, miniature electronic nose (e-nose) system. The e-nose system primarily comprises two self-developed chips, a multiple-walled carbon nanotube (MWNT)-polymer based microsensor array, and a low-power signal-processing chip. The microsensor array was fabricated on a silicon wafer by using standard photolithography technology. The microsensor array comprised eight interdigitated electrodes surrounded by SU-8 "walls," which restrained the material-solvent liquid in a defined area of 650 × 760 μm(2). To achieve a reliable sensor-manufacturing process, we used a two-layer deposition method, coating the MWNTs and polymer film as the first and second layers, respectively. The low-power signal-processing chip included array data acquisition circuits and a signal-processing core. The MWNT-polymer microsensor array can directly connect with array data acquisition circuits, which comprise sensor interface circuitry and an analog-to-digital converter; the signal-processing core consists of memory and a microprocessor. The core executes the program, classifying the odor data received from the array data acquisition circuits. The low-power signal-processing chip was designed and fabricated using the Taiwan Semiconductor Manufacturing Company 0.18-μm 1P6M standard complementary metal oxide semiconductor process. The chip consumes only 1.05 mW of power at supply voltages of 1 and 1.8 V for the array data acquisition circuits and the signal-processing core, respectively. The miniature e-nose system, which used a microsensor array, a low-power signal-processing chip, and an embedded k-nearest-neighbor-based pattern recognition algorithm, was developed as a prototype that successfully recognized the complex odors of tincture, sorghum wine, sake, whisky, and vodka.
authors.affiliation: Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Shih-Wen
authors.initials: SW
authors.lastname: Chiu
authors.forename: Hsiang-Chiu
authors.initials: HC
authors.lastname: Wu
authors.forename: Ting-I
authors.initials: TI
authors.lastname: Chou
authors.forename: Hsin
authors.initials: H
authors.lastname: Chen
authors.forename: Kea-Tiong
authors.initials: KT
authors.lastname: Tang
mesh_terms: D000465:Algorithms; D062609:Electronic Nose; D004867:Equipment Design; D037742:Nanotubes, Carbon / Q000737:chemistry*; D009812:Odorants / Q000032:analysis*; D011108:Polymers / Q000737:chemistry; D012666:Semiconductors; D012984:Software; D014920:Wine / Q000032:analysis*
chemical_list: D037742:Nanotubes, Carbon; D011108:Polymers