Piezoresistive Characteristic of Conductive Rubber for Flexible Tactile Sensor

In the research of 2D flexible tactile sensor matrix,pressure-sensitive conductive rubber was developed and tested in which carbon black was used as its conductive phase and silicon rubber as its matrix layer.Experiments were undertaken and the resultant data were used for its piezoresistive characteristics investigation for two kinds of electrode connection configurations,the surface directive connection and embedded connection.It is found that due to the rather strong nonlinearity of the piezoresistive characteristic curves obtained,a higher correlation relationship can be obtained by means of quadratic polynomial fitting.It also showed that the embedded electrode assembling has higher fitting accuracy while the surface directive connection has better mechanical sensitivity.

3D Printing of Liquid Metal Based Tactile Sensor for Simultaneously Sensing of Temperature and Forces

Tactile sensors have been used for haptic perception in intelligent robotics,smart prosthetics,and human-machine interface.The development of multifunctional tactile sensor remains a challenge and limit its application in flexible electronics and devices.We propose a liquid metal based tactile sensor for both temperature and force sensing which is made by 3D printing.The structural design and working principle of liquid metal based tactile sensor are firstly described.A digital light processing-based printing process is developed to print two kinds of photosensitive resins with different hardness,and used to fabricate the tactile sensor.A Wheatstone bridge circuit is designed for decoupling the temperature and forces from the measured output voltages.Characterization tests show that the tactile sensor has relatively high force sensing sensitivity of 0.29 N^(-1),and temperature sensing sensitivities are 0.55%°C−1 at 20~50°C and 0.21%°C^(−1)at 50~80°C,respectively.Then,the fabricated tactile sensor is mounted onto hand finger to measure the contact force and temperature during grasping.Results show that the 3D printed tactile sensor has excellent flexibility and durability and can accurately measure the temperature and contact forces,which demonstrate its potential in robotic manipulation applications.

Hyperelastic Graphene Aerogels Reinforced by In‑suit Welding Polyimide Nano Fiber with Leaf Skeleton Structure and Adjustable Thermal Conductivity for Morphology and Temperature Sensing

Graphene-aerogel-based flexible sensors have heat tolerances and electric-resistance sensitivities superior to those of polymer-based sensors.However,graphene sheets are prone to slips under repeated compression due to inadequate chemical con-nections.In addition,the heat-transfer performance of existing compression strain sensors under stress is unclear and lacks research,making it difficult to perform real-temperature detections.To address these issues,a hyperelastic polyimide fiber/graphene aerogel(PINF/GA)with a three-dimensional interconnected structure was fabricated by simple one-pot compound-ing and in-situ welding methods.The welding of fiber lap joints promotes in-suit formation of three-dimensional crosslinked networks of polyimide fibers,which can effectively avoid slidings between fibers to form reinforced ribs,preventing graphene from damage during compression.In particular,the inner core of the fiber maintains its macromolecular chain structure and toughness during welding.Thus,PINF/GA has good structural stabilities under a large strain compression(99%).Moreover,the thermal and electrical conductivities of PINF/GA could not only change with various stresses and strains but also keep the change steady at specific stresses and strains,with its thermal-conductivity change ratio reaching up to 9.8.Hyperelastic PINF/GA,with dynamically stable thermal and electrical conductivity,as well as high heat tolerance,shows broad applica-tion prospects as sensors in detecting the shapes and temperatures of unknown objects in extreme environments.