High-Speed Capacitance Scanner

Javad Frounchi and Fahimeh Dehkhoda

Microelectronic and Microsensor Research Laboratory, Electrical Engineering Department, Faculty of Engineering, Tabriz University, Tabriz, Iran

Tel: +98 (0)411 3393722, Fax: +98 (0)411 3300829, Email: jfrounchi@tabrizu.ac.ir

ABSTRACT

A high-speed capacitive scanner employs an array of 8 × 8 small proximity capacitive sensors to reduce significantly the scanning time of an object and a mechanical system to move the sensors in small steps in X and Y directions (a pixel size). A ring-shaped sensor structure is used to increase the sensor sensitivity. The capacitive scanner can be used to determine size, shape, and even type of objects underneath the sensors. The different contributions of the values of the pixel under a sensor and the surrounding pixels are incorporated into a sensitivity map. When the sensitivity map is applied for image reconstruction, the reconstructed images of a metal ring and a word NOISE printed on a metal layer of a PCB resemble very closely to the photos of these objects.

Keywords Planner Capacitive Tomography, Capacitance scanner, Capacitance measurement