Multifunctional electronic skins (e-skins), which mimic the somatosensory system of human skin, have been widely employed in wearable devices for intelligent robotics, prosthetics, and human health monitoring. Relatively low sensitivity and severe mutual interferences of multiple stimuli detection have limited the applications of the existing e-skins. To address these challenges, inspired by the physical texture of the natural fingerprint, a novel fully elastomeric e-skin is developed herein for highly sensitive pressure and temperature sensing. A region-partition strategy is utilized to construct the multifunctional fingerprint-shaped sensing elements, where strain isolation structure of indurated film patterns are further embedded to enhance the sensitivity and effectively reduce mutual interferences between the differentiated units. The fully elastomeric graphene/silver/silicone rubber nanocomposites are synthesized with tunable properties including conductivity and sensitivity to satisfy the requirements of highly sensitive pressure and temperature sensing as well as stretchable electrodes. Remarkable progress in sensitivities for both pressure and temperature, up to 5.53 kPa–1 in a wide range of 0.5–120 kPa and 0.42% °C–1 in 25–60 °C, respectively, are achieved with the inappreciable mutual interferences. Further studies demonstrate the great potential of the proposed e-skin in the next-generation of wearable electronics for human–machine interfaces.

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.

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