Humans can gently slide a finger on the surface of an object and identify it by capturing both static pressure and high-frequency vibrations. Although modern robots integrated with flexible sensors can precisely detect pressure, shear force, and strain, they still perform insufficiently or require multi-sensors to respond to both static and high-frequency physical stimuli during the interaction. Here, we report a real-time artificial sensory system for high-accuracy texture recognition based on a single iontronic slip-sensor, and propose a criterion—spatiotemporal resolution, to corelate the sensing performance with recognition capability. The sensor can respond to both static and dynamic stimuli (0-400 Hz) with a high spatial resolution of 15 μm in spacing and 6 μm in height, together with a high-frequency resolution of 0.02 Hz at 400 Hz, enabling high-precision discrimination of fine surface features. The sensory system integrated on a prosthetic fingertip can identify 20 different commercial textiles with a 100.0% accuracy at a fixed sliding rate and a 98.9% accuracy at random sliding rates. The sensory system is expected to help achieve subtle tactile sensation for robotics and prosthetics, and further be applied to haptic-based virtual reality and beyond.

Post-surgical treatments of the human throat often require continuous monitoring of diverse vital and muscle activities. However, wireless, continuous monitoring and analysis of these activities directly from the throat skin have not been developed. Here, we report the design and validation of a fully integrated standalone stretchable device platform that provides wireless measurements and machine learning-based analysis of diverse vibrations and muscle electrical activities from the throat. We demonstrate that the modified composite hydrogel with low contact impedance and reduced adhesion provides high-quality long-term monitoring of local muscle electrical signals. We show that the integrated triaxial broad-band accelerometer also measures large body movements and subtle physiological activities/vibrations. We find that the combined data processed by a 2D-like sequential feature extractor with fully connected neurons facilitates the classification of various motion/speech features at a high accuracy of over 90%, which adapts to the data with noise from motion artifacts or the data from new human subjects. The resulting standalone stretchable device with wireless monitoring and machine learning-based processing capabilities paves the way to design and apply wearable skin-interfaced systems for the remote monitoring and treatment evaluation of various diseases.

Highlights: The iontronic pressure sensor achieved an ultrahigh sensitivity (S_min > 200 kPa⁻¹, S_max > 45,000 kPa⁻¹). The iontronic pressure sensor exhibited a broad sensing range of over 1.4 MPa. Pseudocapacitive iontronic pressure sensor using MXene was proposed. Flexible pressure sensors are unprecedentedly studied on monitoring human physical activities and robotics. Simultaneously, improving the response sensitivity and sensing range of flexible pressure sensors is a great challenge, which hinders the devices’ practical application. Targeting this obstacle, we developed a Ti₃C₂T_x-derived iontronic pressure sensor (TIPS) by taking the advantages of the high intercalation pseudocapacitance under high pressure and rationally designed structural configuration. TIPS achieved an ultrahigh sensitivity (S_min > 200 kPa⁻¹, S_max > 45,000 kPa⁻¹) in a broad sensing range of over 1.4 MPa and low limit of detection of 20 Pa as well as stable long-term working durability for 10,000 cycles. The practical application of TIPS in physical activity monitoring and flexible robot manifested its versatile potential. This study provides a demonstration for exploring pseudocapacitive materials for building flexible iontronic sensors with ultrahigh sensitivity and sensing range to advance the development of high-performance wearable electronics.

Transition metal dichalcogenides (TMDs) have attracted considerable interest for exploration of next-generation electronics and optoelectronics in recent years. Fabrication of in-plane lateral heterostructures between TMDs has opened up excellent opportunities for engineering two-dimensional materials. The creation of high quality heterostructures with a facile method is highly desirable but it still remains challenging. In this work, we demonstrate a one-step growth method for the construction of high-quality MoS ₂ –WS ₂ in-plane heterostructures. The synthesis was carried out using ambient pressure chemical vapor deposition (APCVD) with the assistance of sodium chloride (NaCl). It was found that the addition of NaCl played a key role in lowering the growth temperatures, in which the Na-containing precursors could be formed and condensed on the substrates to reduce the energy of the reaction. As a result, the growth regimes of MoS ₂ and WS ₂ are better matched, leading to the formation of in-plane heterostructures in a single step. The heterostructures were proved to be of high quality with a sharp and clear interface. This newly developed strategy with the assistance of NaCl is promising for synthesizing other TMDs and their heterostructures.