A Sensing Circuit For Micro-Capacitance Tomography

Iwan Evans, Alan Somerville and Trevor York

Department of Electrical Engineering and Electronics, UMIST, PO Box 88, Sackville Street, Manchester, M60 1QD, UK

Tel: 0161 200 4790 Fax: 0161 200 4789 email:ige@skoda.ee.umist.ac.uk

IE, TY and AS are members of the Virtual Centre for Industrial Process Tomography

Abstract - A circuit is described that has applications for micro scale capacitance tomography. The circuit has been developed for use with linear arrays of rectangular electrodes measuring between 10Dm-100Dm and integrated onto a silicon chip.

Simulations suggest that the circuit is capable of measuring very small

capacitance changes of the order of tens of atto-farads. The circuit also features a small area footprint, which allows the implementation of large arrays of electrodes, and the associated measurement circuitry, onto one integrated circuit.

Keywords: Capacitance, Measurement, VLSI, Micro-Tomography