Liquid Lens‐Based Optical Tactile Sensor with a Touch‐Sensing Separable Structure

Abstract Optical tactile sensing plays an important role in the tactile sensing field, due to its high sensitivity, fast response, and prominent interference immunity. Herein, based on the liquid lens, a low‐cost optical tactile sensor with a touch‐sensing separable structure is designed and fabricated, and it contains a touch unit and an optics sensing unit. The touch unit is a chamber structure with good integration, and the optics sensing unit is designed with a liquid‐membrane structure. Different from the existed optical tactile sensors, the principle of the proposed sensor is that the focal length of the optics sensing unit is changed with an external contact force, and then the directional light propagation direction produces change, which affects the perceived light intensity of the silicon photocell. From the sensing performance test results, this tactile sensor has good statics and dynamics performance, which embodies in the rapid response time (about 0.048 s), stable output, high sensitivity (the max sensitivity is about 7.1338 V/N), and resolution (0.01 N), low hysteresis ratio (less than 6.5%), and good linearity (R² ≈ 0.98). In addition, some application experiments are conducted and the results demonstrate the application feasibility of the proposed sensor in health monitoring and multichannel sensing.