Extremely Stretchable and Self-Healable Electrical Skin with Mechanical Adaptability, an Ultrawide Linear Response Range, and Excellent Temperature Tolerance

Abstract

Artificial electronic skin (e-skin) that imitates the complex functions of human skin is able to transduce external stimuli into electronic signals. However, it remains challenging to fabricate e-skin sensing materials with extreme stretchability, self-healing, mechanical compliance, extreme temperature tolerance, and an ultrawide linear response range. Here, we demonstrate a new e-skin sensor fabricated by introducing polyvinylpyrrolidone (PVP)-capped Ag nanowires into the chemically and physically cross-linked polyacrylamide–PVP double-network ethylene glycol organogel. The resulting organogel e-skin exhibits extreme stretchability (>22 000%), autonomous self-healing, as well as mechanical compliance. Particularly, the sensor is capable of antifreezing and antiheating (−20 to 80 °C) and provides an ultrawide linear response range with a gauge factor of 0.15 for 0–430% tensile strain and 0.71 for 430–18 100% tensile strain, respectively. By dynamically accommodating to a curved surface, the e-skin sensor demonstrates comprehensive applications in real-time and in situ tracking of large body deformations, spatial gesture movements, and physiological signals for motion behaviors and health level evaluation, showing great promise in wearable electronics, biomedical devices, and soft robotics.

Highly Stretchable, Elastic, and Sensitive MXene-Based Hydrogel for Flexible Strain and Pressure Sensors

“…The sensitivity of a strain sensor is defined as a gauge factor (GF) and calculated by the formula: GF = (Δ R / R 0 )/ ε , where Δ R = R − R 0 and R 0 and R are the raw resistance and the resistance under deformation, respectively. ε is the applied strain [ 15 , 30 , 31 ]. In the MDN hydrogel, the highly conductive MXene nanosheets form a 3D conductive network for electron conduction, presenting a predominant impact on the piezoresistive property.…”

“…Nevertheless, it is still challenging to combine good mechanical property with high sensing performance to design a highly stretchable and sensitive strain sensing hydrogel for wearable electronics. Recently, conductive materials, such as conductive polymers, carbon nanomaterials, and metal nanoparticles, have been incorporated into a polymer matrix to improve the electromechanical performances of hydrogel-based strain sensors [ 13 – 15 ]. For example, carbon nanomaterials could greatly increase the elongation of the hydrogel due to strong interaction between their rich surface groups and polymer skeleton.…”

Materials, Electrical Performance, Mechanisms, Applications, and Manufacturing Approaches for Flexible Strain Sensors

“…In addition, other low strain motions, such as swallowing, [ 134 , 179 , 191 ] voice vibrations, [ 164 , 192 , 193 ] pulsing, [ 29 , 135 ] blowing, [ 194 , 195 ] and neck joint motion [ 196 , 197 ] biomedical test have also been presented by different composites. On the other hand, large strain movements, including finger [ 198 , 199 ] and knee bending [ 200 , 201 ], wrist [ 60 ] and elbow motions [ 202 , 203 ], plantar distribution [ 204 ], respiration rate [ 205 ], and some derived sports behaviors requires high stretchability and better sensitivity of the sensors. For example, a strain sensor with multidirectional sensing capability and high GF value of 180 has been introduced based on carbon nanofiber-PDMS composites [ 206 ].…”

Highly Compressible, Thermally Stable, Light-Weight, and Robust Aramid Nanofibers/Ti3AlC2 MXene Composite Aerogel for Sensitive Pressure Sensor

“…With the rapid development of the intelligent industry, wearable sensor devices are constantly emerging in all aspects of people’s lives including bionic limbs, healthy sports monitoring devices, and medical devices, − most of which make a healthy lifestyle compatible with convenience, energy efficiency, and intellectualization. At the same time, high-performance pressure sensors play a critical role in wearable sensor devices.…”