A Stretchable Dual-mode Sensor Array For Multifunctional Robotic Electronic Skin

Proximity sensing and tactile sensing are an integral part of the intelligent robot sensing system.The robot relies on the proximity sensor and the tactile sensing sensor to realize the whole process monitoring from sensing the object position to grasping the object.Aiming at a series of defects,such as single function,poor stretchability,low sensitivity and narrow measurement range,the robot electronic skin sensor is designed for the Stretchable Dual-mode Sensor Array for Multifunctional Robotic Electronic Skin.We have done the following main tasks:(1)This paper designs a stretchable dual-mode sensor array for multifunctional robotic electronic skin.The sensor can perform pressure sensing measurement in both the triboelectric nanogenerator and capacitive mode.The sensor can also perform proximity sensing and tensile strain measurement in capacitive mode.Simultaneously,we used COMSOL to simulate the proximity characteristics of sensors with different structures,and Selected the final structure of the sensor from the results;(2)In order to ensure the tensile properties of the sensor,the sensor uses Galinstan as the electrode material and PDMS as the base material.In order to improve the sensitivity of the sensor in the pressure measurement based on the triboelectric nanogenerator mode,we designed the sandpaper microstructure on the sensor surface.In order to improve the sensitivity of the sensor in the capacitive mode,we designed hollow micro-pillars in the dielectric layer;(3)Prepare the process flow and prepare the experiment according to the structure and material characteristics of the designed sensor.The sensor array is prepared by the liquid metal to the hydrophilicity and hydrophobicity of gold and PDMS.The dielectric layer with the hollow micro-pillars is prepared by soft lithography and PDMS secondary mold.The sandpaper surface microstructure is replicated on the PDMS surface by sandpaper molding;the final package of the sensor is completed by reactive ion etching;(4)The sensor's relevant characteristics are measured.The sensor can position the finger at a distance of 10 cm.In the low pressure range(<12KPa),the sensitivity of the sensor based on the triboelectric generator mode can reach 1.04V/KPa,at the high pressure(12KPa~120KPa),the sensitivity of the sensor based on capacitive mode can reach 1.4MPa-1.The complement of the pressure intervals of the two sensing modes makes the pressure measurement interval of the sensor reach <120KPa,and the sensor can also measure the pressure of about 10Pa;The measurement sensitivity of tensile strain can be up to-1.23,and the sensor can distinguish the pressure and tensile strain;Finally,we also completed the preliminary application of the sensor array and unit on the bionic hand.With the 3D shape sensing ability of the space conductor,the sensor array can clearly recognize the spatial shape characteristics of the orange at a short distance(about 3 cm),and can sense the presence of orange at a long distance(10 cm);The sensor was used for the pressure tactile measurement experiment of the bionic hand.In the low pressure range(<12KPa),the sensor showed good pressure measurement capability in the triboelectric nanogenerator mode.In the high pressure range(12KPa~120KPa),the mapping of capacitance changes in the sensors is also consistent with the measurements from commercial sensors.