Wireless Inductive Displacement Sensor 3-D Printed Using Additive Technology

This article presents an application of 3-D printing technology for the production of a flexible inductive displacement sensor. In order to achieve wireless measurements, the sensor is designed in the form of an Archimedean spiral. An additional more complex structure consisting of two spirals was also examined. When displacement is applied to the spiral center, an increase in the distance between the adjacent turns of the spiral is achieved. As a result, there will be a decrease in inductance and a consequent change in the sensor’s self-resonant frequency. The change in resonant frequency is detected using an external coil (antenna) adapted to the sensor. The sensors are read by determining their phase-dip minimum or phase-peak maximum. This way the resonant frequency versus displacement characteristics are obtained. The displacement measurement range is up to 30 mm. The calculated sensitivity of the proposed single and double sensor spiral systems are 1.54 and 0.19 MHz/mm respectively.