A planar capacitive sensor(PCS) capable of 2D large-scale measurement is presented in this paper.Displacement interpretation depends on independently measuring the periodic variation in capacitance caused by the change in the overlapping area of sensing electrodes on a moving plate and a fixed plate.By accumulating the number of quarters in each direction and the specific position in the final quarter,the large-scale measurement is fulfilled.Displacements in Xand Y-direction can be measured independently and simultaneously.Simulation shows that a shorter gap distance and a longer electrode guarantee better sensitivity.Experiments based on a PCS test bench demonstrate that the PCS has a sensitivity of 0.198 mV/μm and a resolution of 0.308 μm.An electric fringe effect and other possible measurement errors on displacement interpretation accuracy are discussed.The study confirms the high potential of PCSs as innovative 2D long-range displacement sensors.
