and positions between the robots and the interacted objects. [6] Thus, various kinds of the pressure sensors have been designed and applied as different force sensing interfaces. [7,8] Although the pressure sensors are attracting great attention in robot field, the limited sensing function, rigid structure and complicated back-end data processing still raise the requirements of further advancement in the robot safety detection. Flexible electronic skin (e-skin) has been widely applied in wearable devices, artificial prosthetics, health monitoring, and smart robots as it can mimic human skin functions and convert the external stimuli into different output signals through various sensors. [9-12] Among them, tactile e-skin is drawing the attention, including human-computer interfaces, medical and security systems. [13-16] Generally, the tactile sensors based on capacitive, [17,18] piezoelectric, [19-21] resistive, [22-24] and optical [25] mechanisms rely on the deformation produced by the interaction between the sensing unit and the object. Thus, the tactile sensor will occasionally generate the unstable and insensitive signals and lead to poor detection for very weak interactions. Meanwhile, the tactile sensors often require the external power source to sense the environmental stimuli. In addition, it is noted that the reported tactile sensors are mainly focusing on the tactile sensing without the direct visualization capability. The skin of specific animal species has extra functions that can change their colors when they are activated by external stimuli. Both vertebrates and invertebrates use various strategies for visualization and camouflage. For example, Chameleons can prey, camouflage protection, and even communicate through the ability of color changing. [26] Inspired by this, it is also possible to mimic the color conversion function of chameleons through mechanical or electronic equipment. [27-30] Whitesides and his colleague reported a soft machine with a microfluidic channel that could be filled or rinsed by pumping a colored liquid. [31] Rogers's team fabricated an adaptive optoelectronic camouflage system that used a bright-colored composite, producing a black-and-white pattern to match the surrounding environment. [32] A soft material system presented by Wang et al. produced voltage-controlled on-demand fluorescent patterns which could be modulated to display a variety of geometries. [33] However, these mentioned devices can only

The biocompatible strechable ionogels were prepared by a facile solution-processed method. The ionogels showed outstanding stretchable and self-healing properties. The electrical property could revert to its original state after 4 s. The repaired ionogels could still bear stretching about 150%. Moreover, the ionogels exhibited high sensitivity and wide-detection range to temperature. The temperature-sensitive sensor could detect the human breath frequency and intensity, showing potential application in detecting disease.

Temperature is one of the key parameters for activity of cells. The trade-off between sensitivity and biocompatibility of cell temperature measurement is a challenge for temperature sensor development. Herein, a highly sensitive, biocompatible, and degradable temperature sensor was proposed to detect the living cell extracellular environments. Biocompatible silk materials were applied as sensing and packing layers, which endow the device with biocompatibility, biodegradability, and flexibility. The silk-based temperature sensor presented a sensitivity of 1.75%/°C and a working range of 35–63 °C with the capability to measure the extracellular environments. At the bending state, this sensor worked at promising response of cells at different temperatures. The applications of this developed silk material-based temperature sensor include biological electronic devices for cell manipulation, cell culture, and cellular metabolism.

Wearable smart glove of gesture language provides a novel strategy for the hearing‐impaired people to commutate with the world. Current commercialized solutions of gesture language are limited by the full extent of human interaction beyond operation dexterity, sensory feedback, and the huge cost of fabrication. Herein, a low‐cost, high‐efficient gesture‐language‐recognition feedback system combined with the strain‐sensor arrays and machine‐learning technology is proposed. The strain‐sensor arrays integrated with 3D‐printed glove can extract both spatial and temporal information about the finger's movement. The smart glove achieves gesture‐language recognition using machine learning with an accuracy of over 99%. Integrating with multidimensional manipulation, visual feedback and artificial intelligence (AI)‐based gesture‐language recognition, the smart system can accurately recognize complex gestures and provide real‐time feedback to users. The smart glove system can not only provide an efficient way for hearing‐impaired persons to communicate with the outside world, but also benefit industries in multiple fields such as entertainment, home healthcare, sports training, and the medical industry.

Total knee arthroplasty (TKA) is a common treatment for terminal knee arthropathy. Soft tissue balance is one of the key factors affecting the success rate of TKA. However, current measurement systems still face great challenges in terms of accuracy and timeliness. Herein, a novel force measurement system based on a smart spacer is proposed to measure soft tissue balance in a timely and accurate manner. The smart spacer is designed according to the simulated results, where six flexible pressure sensors with a high sensitivity of 99.56 N−1 and a wide detection range of 50 N are attached to the spacer base to directly detect the soft tissue balance force. Moreover, a soft tissue balance measurement system is constructed, which can measure the force at different positions, such as the extension position (0°), the middle position (45°), and the flexion position (90°), and display them on the computer in a timely manner. This novel real‐time knee soft tissue balance measurement system provides a way for surgeons or knee joint replacement surgery robots to accurately evaluate soft tissue balance and paves the way for improving the success rate of TKA and the patient's postoperative rehabilitation.