DocumentCode :
1504841
Title :
A CMOS Gas Sensor Array Platform With Fourier Transform Based Impedance Spectroscopy
Author :
Murali, P. ; Ranjit, K. ; Bhat, N. ; Banerjee, G. ; Amrutur, B. ; Bhat, K.N. ; Ramamurthy, P.C.
Author_Institution :
Centre of Nanosci. & Eng., Indian Inst. of Sci., Bangalore, India
Volume :
59
Issue :
11
fYear :
2012
Firstpage :
2507
Lastpage :
2517
Abstract :
A CMOS gas sensor array platform with digital read-out containing 27 sensor pixels and a reference pixel is presented. A signal conditioning circuit at each pixel includes digitally programmable gain stages for sensor signal amplification followed by a second order continuous time delta sigma modulator for digitization. Each sensor pixel can be functionalized with a distinct sensing material that facilitates transduction based on impedance change. Impedance spectrum (up to 10 KHz) of the sensor is obtained off-chip by computing the fast Fourier transform of sensor and reference pixel outputs. The reference pixel also compensates for the phase shift introduced by the signal processing circuits. The chip also contains a temperature sensor with digital readout for ambient temperature measurement. A sensor pixel is functionalized with polycarbazole conducting polymer for sensing volatile organic gases and measurement results are presented. The chip is fabricated in a 0.35 μm CMOS technology and requires a single step post processing for functionalization. It consumes 57 mW from a 3.3 V supply.
Keywords :
CMOS integrated circuits; delta-sigma modulation; digital readout; fast Fourier transforms; gas sensors; signal conditioning circuits; spectroscopy; temperature measurement; CMOS gas sensor array platform; Impedance spectrum; ambient temperature measurement; digital programmable gain stage; digital read-out; digitization; fast Fourier transform based impedance spectroscopy; polycarbazole conducting polymer; power 57 mW; reference pixel; second order continuous time delta sigma modulator; sensor signal ampliήcation; signal conditioning circuit; single step post processing; size 0.35 mum; temperature sensor; volatile organic gas sensor; voltage 3.3 V; Arrays; CMOS integrated circuits; Gain; Impedance; Materials; Modulation; Sensors; CMOS; FFT; delta-sigma; impedance spectroscopy; sensor array;
fLanguage :
English
Journal_Title :
Circuits and Systems I: Regular Papers, IEEE Transactions on
Publisher :
ieee
ISSN :
1549-8328
Type :
jour
DOI :
10.1109/TCSI.2012.2189062
Filename :
6191335
Link To Document :
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