A Force Measurement Method Based on Flexible PDMS Grating

Abstract

With the rapid development of flexible materials, various high-performance biocompatible flexible sensors have been proposed for specific measurement applications. Among these materials, polydimethylsiloxane (PDMS) is one of the most popular polymers by curing the mixture of pre-polymer (base) and cross-linker (curing agent). In this paper, a force measurement method based on PDMS grating is introduced. The PDMS grating is cast from a commercial master grating, which is precise, low-cost, and easy to follow. The elastic modulus can be controlled by the curing temperature and the mixing ratio. The PDMS grating is tested using a tension testing machine. As the stretching force increases, the grating line-spacing simultaneously increases and the diffraction light spot shifts. By capturing the light spot shift using a camera, the relationship between light spot position and stretching force is established and evaluated. Experimental results show that the linearity (R2) of the proposed method is better than 0.998, adding that the sensitivity is ~0.5–0.7N/mm and the accuracy is up to 0.05N.