3D Printed Interdigitated Capacitor Based Tilt Sensor

Abstract

This paper presents a tilt sensor comprising of 3D printed capacitive sensors located at the four ends of a '+' shaped channel to provide the orientation of objects by using the capacitive fluid level measurement concept. The interdigitated capacitive sensors were developed by 3D printing and the channel was filled with ecoflex and silicone oil to obtain two variants of tilt sensor. The results show a change in the capacitance of 11.5% and 9.53% for ecoflex and silicone oil-based sensors respectively. A drift of 2.6% is observed for ecoflex and 0.16% for silicone oil. Considering the lower viscosity and the lower drift, the silicone oil-based tilt sensors were further investigated and two tilt sensors with varying silicone volumes (1 ml and 1.5 ml) were fabricated and compared for tilt angles ranging from 0° to 30°. The result from all four interdigitated capacitive sensors in the tilt sensing structure show similar rate of change in capacitance (0.67% per degree increase in the tilt angle) with a standard deviation of ±0.1%. However, the sensor with higher volume of silicone oil (1.5 ml) saturated at a tilt angle of 20° which is 10° smaller than the response of the sensor fabricated with 1 ml of silicone oil (saturated at 30°). We also demonstrate the possibility of extending the sensor range by optimizing the volume of fluid and the channel's fluid capacity. With integration of fabricated tilt sensor with a robots' body, white cane or smart objects etc., it will be possible to obtain the information about orientation.