Broad‐range‐response pressure‐sensitive wearable electronics are urgently needed but their preparation remains a challenge. Herein, we report unprecedented bioinspired wearable electronics based on stretchable and superelastic reduced graphene oxide/polyurethane nanocomposite aerogels with gradient porous structures by a sol‐gel/hot pressing/freeze casting/ambient pressure drying strategy. The gradient structure with a hot‐pressed layer promotes strain transfer and resistance variation under high pressures, leading to an ultrabroad detection range of 1 Pa–12.6 MPa, one of the broadest ranges ever reported. They can withstand 10 000 compression cycles under 1 MPa, which can't be achieved by traditional flexible pressure sensors. They can be applied for broad‐range‐response electronic skins and monitoring various physical signals/motions and ultrahigh pressures of automobile tires. Moreover, the gradient aerogels can be used as high‐efficient gradient separators for water purification.

Recently, with the increasing demand for artificial skins and human bodily motion/physical signals monitoring, flexible pressure sensors with a wide detection range are urgently needed. Transparent and stretchable gels with ionic conductivities are considered to be ideal candidates for flexible pressure sensors. However, the gel-based pressure sensors usually show a relatively narrow detection range, which significantly limits their practical applications. Herein, we report an unprecedented bioinspired highly flexible modulus/conductivity-dual-gradient poly(ionic liquid) (PIL) ionogel, which is achieved by constructing three layers of PIL ionogels with different monomer concentrations via a layer-by-layer gelation method. The flexible pressure sensor based on the gradient PIL ionogel exhibits an ultrabroad detection range of 10 Pa−1 MPa. This wearable pressure sensor is highly stable in environments and able to monitor both the tiny pressures as low as 10−100 Pa and the high pressures up to 0.1−1 MPa during human body movements. This work provides a powerful strategy for the preparation of flexible gradient materials that are promising for wearable electronics with a wide pressure detection range.

Broad-range-response pressure-sensitive wearable electronics are urgently needed but their preparation remains a challenge. Herein, we report unprecedented bioinspired wearable electronics based on stretchable and superelastic reduced graphene oxide/ polyurethane nanocomposite aerogels with gradient porous structures by a sol-gel/hot pressing/freeze casting/ambient pressure drying strategy. The gradient structure with a hot-pressed layer promotes strain transfer and resistance variation under high pressures, leading to an ultrabroad detection range of 1 Pa-12.6 MPa, one of the broadest ranges ever reported. They can withstand 10 000 compression cycles under 1 MPa, which can't be achieved by traditional flexible pressure sensors. They can be applied for broad-rangeresponse electronic skins and monitoring various physical signals/motions and ultrahigh pressures of automobile tires. Moreover, the gradient aerogels can be used as high-efficient gradient separators for water purification.

With the increasing demand for electronic skin, health management, and extreme pressure monitoring, development of broad-response-range flexible pressure sensors is in urgent need. However, the reported flexible pressure sensors usually show a narrow detection range. It’s a great challenge to achieve a broad detection range of 1 Pa-10 MPa for a flexible pressure sensor. Herein, unprecedented bioinspired wearable pressure sensors based on highly stretchable reduced graphene oxide/polyurethane foam composite aerogels with modulus-gradient porous structures have been reported. A hot pressing method is applied to increase the modulus and compressive strength of the high-modulus layer of the aerogel, which ensures their compressibility at high pressures and significantly enhances the upper detection limit. Benefiting from their unique superelastic (90-99% reversible strain) and gradient structures with the gradient modulus spanning from 5.4 kPa to 430 kPa and gradient compressive stress (at 90% strain) spanning from 25 kPa to 37 MPa, the resulting pressure sensors exhibit a record-breaking detection range of 1 Pa-12.6 MPa. In addition, the pressure sensors can withstand 10000 cycles at a high pressure of 1 MPa, which can’t be achieved by traditional flexible pressure sensors. This work provides a versatile and powerful strategy towards next-generation high-performance broad-response-range flexible electronics.

Highly stretchable aerogels are promising for flexible electronics but their fabrication is a great challenge. Herein, several kinds of unprecedented intrinsically super-stretchable conductive aerogels with low or negative Poisson’s ratios are achieved by uniaxial, biaxial, and triaxial hot-pressing strategies. The highly elastic reduced graphene oxide/polymer nanocomposite aerogels with folded porous structures obtained by uniaxial hot pressing exhibit record-high stretchability up to 1200% strain, significantly surpassing all those of the reported intrinsically stretchable aerogels. Furthermore, the never-before-realized meta-aerogels with reentrant porous structures combining high biaxial (or triaxial) stretchability and negative Poisson’s ratios have been achieved by biaxial (or triaxial) hot pressing. The resulting aerogel-based wearable strain sensors exhibit a record-wide response range (0-1200%). In addition, they can be applied for smart thermal management and electromagnetic interference shielding, which are achieved by regulating the porous microstructures via stretching. This work provides a versatile strategy to highly stretchable and negative-Poisson-ratio porous materials promising for various applications including but not limited to flexible electronics, thermal management, electromagnetic shielding, and energy storage.

Flexible wearable pressure sensors with high sensitivity and broad sensing range have promoted the vigorous development of flexible electronics. Currently, most of the self-powered flexible pressure sensors are built mainly based on piezoelectric and triboelectric types, which can usually only detect dynamic pressure. They may also be built by integrating batteries or capacitors with sensors, which results in low integration and limits the development of sensor miniaturization. Here, we report a novel battery-type all-in-one self-powered stretchable pressure sensor with porous polyurethane foam (PUF)/V2O5/polypyrrole (PPy) composite as both cathode and pressure-sensitive layer, hot-pressed porous PUF/carbon nanotube (CNT)/PPy composite as anode, and polyacrylamide (PAM) ionic gel as electrolyte. This self-powered flexible pressure sensor has an excellent sensing performance combining good cyclicity (at least 5000 cycles under 40% compressive strain), high sensitivity (141.5 kPa-1), and broad sensing range (1.8 Pa-1.5 MPa). Moreover, its response is small under 50% tensile strain, demonstrating the good stability against stretching. More importantly, this battery-type all-in-one self-powered pressure sensor can address the limitations that the current piezoelectric and triboelectric self-powered pressure sensors can usually only detect dynamic pressure. This work provides a new strategy for the design of novel next-generation all-in-one self-powered miniaturized pressure-sensitive wearable electronics.

Highly stretchable aerogels are promising for flexible electronics but their fabrication is a great challenge. Herein, several kinds of unprecedented intrinsically highly stretchable conductive aerogels with low or negative Poisson’s ratios are achieved by uniaxial, biaxial, and triaxial hot-pressing strategies. The highly elastic reduced graphene oxide/polymer nanocomposite aerogels with compressed and folded porous structures obtained by the uniaxial hot-pressing method exhibit record-high stretchability up to 1200% strain, significantly surpassing all those of the reported intrinsically stretchable aerogels (usually ≤200%). In addition, the meta-aerogels with reentrant porous structures that combine high biaxial stretchability and negative Poisson’s ratios have been obtained by the biaxial hot-pressing method for the first time. Furthermore, the never-before-realized meta-aerogels combining high triaxial stretchability and negative Poisson’s ratios have been achieved by constructing the reentrant porous structures via the triaxial hot-pressing method. The wearable strain sensors based on the resulting aerogels exhibit a record-wide response range (0-1200%). In addition, they can be applied for smart thermal management and electromagnetic interference shielding, which are achieved by regulating the porous microstructures simply via stretching. This work provides a versatile and simple strategy to highly stretchable and negative-Poisson-ratio aerogels promising for various applications including but not limited to flexible electronics, thermal management, electromagnetic shielding, and energy storage.

Recently, with the increasing demand for artificial skins and human bodily motion/physical signals monitoring, flexible pressure sensors with a wide detection range are urgently needed. Transparent and stretchable gels with ionic conductivities are considered to be ideal candidates for flexible pressure sensors. However, the gel-based pressure sensors usually show a relatively narrow detection range, which significantly limits their practical applications. Herein, we report an unprecedented bioinspired highly flexible modulus/conductivity-dual-gradient poly(ionic liquid) (PIL) ionogel, which is achieved by constructing three layers of PIL ionogels with different monomer concentrations via a layer-by-layer gelation method. The flexible pressure sensor based on the gradient PIL ionogel exhibits an ultrabroad detection range of 10 Pa-1 MPa. This wearable pressure sensor is highly stable in environments and able to monitor both the tiny pressures as low as 10-100 Pa and the high pressures up to 0.1-1 MPa during human body movements. This work provides a powerful strategy for the preparation of flexible gradient materials that are promising for wearable electronics with a wide pressure detection range.