Development of a planar type micro electro magnetic distance sensor using high aspect ratio photoresist and its application

In this paper, a planar type micro electromagnetic distance sensor has been developed for the distance sensor of micro mobile robot. So far, because of the use of common photoresist, the thickness of the sensors has in the past only reached several μm. Therefore the sensors fabricated had low measuring accuracy. In order to obtain high sensitivity, using ultrathick high aspect ratio photoresist SU-8, a 300-μm-thick microcoil has been fabricated by micromachining technique based on sputtering and electroplating methods. The microcoil has a spiral planar ultrathick structure. The static characteristics and frequency response of the microcoil have been measured, and sensitivity and position control of the microcoil were determined. The experimental results show that the electromagnetic distance sensor has wide frequency response and high measuring accuracy