A differential structure based on a compression stage, which has negative displacement coefficient unit (NDCU) and positive displacement coefficient unit (PDCU), is designed to improve the sensitivity of the displacement measurement. The sensing material in the compression-stage-based differential displacement sensing device is made of conductive polymer composite, which has a critical deformation. If the deformation of the composite is less/more than the critical deformation, the composite is at the negative/positive compression stage, which results in the decrease/increase of the electrical resistance in the composite with the increase in the deformation. To ensure that NDCU/PDCU is at the negative/positive compression stage, the initial deformation of the composite in NDCU/PDCU is set to a value less/more than the critical deformation. By using NDCU and PDCU as the neighboring arms of an electrical bridge, the displacement is converted into the voltage. The experimental results show that the sensitivity can be improved using the compression-stage-based differential structure. [2015-0334]