A low-cost inductive proximity sensor for industrial applications

In this paper, we present an inductive proximity sensor with fully integrated electronics. The sensor with the compact hybrid configuration is composed of a sensing flat coil and an integrated electronic interface. We focused during the development on the temperature stability and robustness of the sensor by keeping its low-fabrication cost. The sensor exhibits a longitudinal resolution of 120 nm for an aluminum target position up to 500 mum from the sensing coil with the side size of 3.5 mm. The temperature drift of the sensor is less than 700 ppm/degreesC for the same range of the target position. The total working range is from 100 to 1500 mum. The sensor power consumption is 100 mW and the active sensor dimensions are 3.5 turn x 3.5 turn x 1.2 mm. We also showed the facility of the sensor packaging. This kind of integrated sensor has the potential for even more industrial applications. (C) 2003 Elsevier B.V. All rights reserved.