E-Nose: Multichannel Analog Signal Conditioning Circuit with Pattern Recognition for Explosive Sensing

Palaparthy, VS and Doddapujar, SN and Gupta, G and Das, P and Chandorkar, SA and Mukherji, S and Baghini, MS and Rao, VR (2020) E-Nose: Multichannel Analog Signal Conditioning Circuit with Pattern Recognition for Explosive Sensing. In: IEEE Sensors Journal, 20 (3). pp. 1373-1382.

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Abstract

This paper presents E-Nose, a novel cost-effective, field-deployable portable system that constitutes a 4-channel signal conditioning circuit and multi-coated piezo-resistive micro-cantilever sensors for explosive sensing. E-Nose also features an embedded PCA and K-means based pattern recognition (PR) algorithm for the classification of explosives from non-explosives. The 4-channel configuration is a stack of two 2-channel circuits that are capable of measuring the change in the sensor resistance or capacitance in four optional modes of � R - � R, � R - � C , � C- � R , and � C - � C by using time multiplexing. The circuit uses a bidirectional AC current excitation method to drive the sensor bridge for significant reduction of DC offset errors, 1/f noise, line noise, and DC drifts. The proposed signal conditioning circuit uses the phase-sensitive synchronous rectification (PSSR) method for AC-to-DC conversion by using balanced demodulation. The circuit can measure a wide range of resistors that range from 100 Ω to 4 MΩ , with a sensitivity of 0.4mV/ppm and the worst relative error of 2.6. The capacitive measurement range is from 100pF to 100 μF with the worst relative error of 3.3. The entire data processing and the PR algorithms run on Raspberry Pi (R-Pi), which is integrated into the E-Nose system. The system performance is tested with MEMS cantilevers for the detection of explosive compounds, such as TNT and its derivatives, RDX and PETN in a controlled environment at a concentration that was as low as 16ppb TNT, 56ppb RDX and 134ppb of PETN. Measurements show that the E-Nose can detect explosives with 77 as true positive results without considering the environmental and mixed vapor effects.

Item Type:	Journal Article
Publication:	IEEE Sensors Journal
Publisher:	Institute of Electrical and Electronics Engineers Inc.
Additional Information:	Copyright of this article belongs to IEEE
Keywords:	Cost effectiveness; Digital storage; Electric rectifiers; Electronic nose; Errors; Explosives; Explosives detection; K-means clustering; Nanocantilevers; Pattern recognition; Rectifying circuits; Strain measurement; Timing circuits, AC currents; Capacitive sensing; Multi coating; Phase sensitive; Piezo-resistive cantilevers, Signal conditioning circuits
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	14 Feb 2020 09:51
Last Modified:	14 Feb 2020 09:51
URI:	http://eprints.iisc.ac.in/id/eprint/64513

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