Miniaturization of mechanical actuators in skin-integrated electronics for haptic interfaces

Skin-integrated electronics,also known as electronic skin(e-skin);are rapidly developing and are gradually being adopted in biomedical fields as well as in our daily lives.E-skin capable of providing sensitive and high-resolution tactile sensations and haptic feedback to the human body would open a new e-skin paradigm for closed-loop human-machine interfaces.Here,we report a class of materials and mechanical designs for the miniaturization of mechanical actuators and strategies for their integration into thin,soft e-skin for haptic interfaces.The mechanical actuators exhibit small dimensions of 5 mm diameter and 1.45 mm thickness and work in an electromagnetically driven vibrotactile mode with resonance frequency overlapping the most sensitive frequency of human skin.Nine mini actuators can be integrated simultaneously in a small area of 2 cm×2 cm to form a 3×3 haptic feedback array,which is small and compact enough to mount on a thumb tip.Furthermore,the thin,soft haptic interface exhibits good mechanical properties that work properly during stretching,bending,and twisting and therefore can conformally fit onto various parts of the human body to afford programmable tactile enhancement and Braille recognition with an accuracy rate over 85%.

Muscle-inspired soft robots based on bilateral dielectric elastomer actuators

Muscle groups perform their functions in the human body via bilateral muscle actuation,which brings bionic inspiration to artificial robot design.Building soft robotic systems with artificial muscles and multiple control dimensions could be an effective means to develop highly controllable soft robots.Here,we report a bilateral actuator with a bilateral deformation function similar to that of a muscle group that can be used for soft robots.To construct this bilateral actuator,a low-cost VHB 4910 dielectric elastomer was selected as the artificial muscle,and polymer films manufactured with specific shapes served as the actuator frame.By end-to-end connecting these bilateral actuators,a gear-shaped 3D soft robot with diverse motion capabilities could be developed,benefiting from adjustable actuation combinations.Lying on the ground with all feet on the ground,a crawling soft robot with dexterous movement along multiple directions was realized.Moreover,the directional steering was instantaneous and efficient.With two feet standing on the ground,it also acted as a rolling soft robot that can achieve bidirectional rolling motion and climbing motion on a 2°slope.Finally,inspired by the orbicularis oris muscle in the mouth,a mouthlike soft robot that could bite and grab objects 5.3 times of its body weight was demonstrated.The bidirectional function of a single actuator and the various combination modes among multiple actuators together allow the soft robots to exhibit diverse functionalities and flexibility,which provides a very valuable reference for the design of highly controllable soft robots.