Novel Sensors of the Linear Displacement Measurement With High-Resolution for Mechatronics Applications

Abstract

A displacement sensor with high resolution is presented in this paper using an elastic sphere that acts as the sensing element; which can be used in several applications of mechatronics. To have the elastic behavior for the sensing element, the sphere was made from polymeric material with 600µm in diameter. The sphere vibrates mechanically in response to a time varying displacement excited by piezo-stack actuator (PZT). The mechanical vibration transmitted to the elastic sphere was monitored optically based on tracking the optical resonance shifts on the transmission spectrum, in turn the displacement of the piezo-stack actuator can be determined. The sphere was lying between two micro-sticks made from silica with ~80µm in diameter for each with ~3cm long; one of them is fixed while the other is mechanically connected to the PZT. By moving the PZT, the displacement was fully transmitted to the sensing element leading to a change in its morphology and therefore shifts of its optical resonances. By tracking these shifts and comparing them with typical electronic strain gauges used within piezo-nanopositioners, it is possible to determine the displacement of the PZT in high resolution. The resolution for the new design was recorded to be up to ~3.16nm with sensitivity up to ~2nm/µm. The novelty for the proposed design could be used for several mechatronics applications like the feedback on the linear actuators for the micro/nano robots, and also it can extend for structural health monitoring in nanoscale.