Temperature-resistant and flexible supercapacitors based on 10-inch wafer-scale nanocarbon films

Most of the supercapacitors reported in literatures showed little or no flexibility in the working temperature around 150℃. However, the supercapacitors are generally exposed under complex system or extreme temperature, such as electric vehicles and extremely cold area. Herein, we successfully fabricated a large-scale robust nanocarbon hybrid film consisting of reduced graphene oxide (rGO), carbon nanotubes (CNTs) and MnOx nano-flowers with the size up to 550 cm^2. The mechanical properties of the hybrid films depend on the ratio o f CNTs. The supercapacitors prepared with the hybrid films exhibit high flexibility and keep their performances in a temperature range from - 20 to 200℃. In addition, the devices display remarkable electrochemical and deformation stability at extrem e temperature. This strategy has a potential for the more efficient preparation of flexible electrode materials.

CVD growth of fingerprint-like patterned 3D graphene film for an ultrasensitive pressure sensor

With the rapid development of wearable devices, flexible pressure sensors with high sensitivity and wide workable range are highly desired. In nature, there are many well-adapted structures developed through natural selection, which inspired us for the design of biomimetic materials or devices. Particularl3 human fingertip skin, where many epidermal ridges amplify external stimulations, might be a good example to imitate for highly sensitive sensors. In this work, based on unique chemical vapor depositions （CVD）-grown three-dimensional （3D） graphene films that mimic the morphology of fingertip skin, we fabricated flexible pressure sensing membranes, which simultaneously showed a high sensitivity of 110 （kPa）-1 for 0-0.2 kPa and wide workable pressure range （up to 75 kPa）. Hierarchical structured polydimethylsiloxane （PDMS） films molded from natural leaves were used as the supporting elastic films for the graphene films, which also contribute to the superior performance of the pressure sensors. The pressure sensor showed a low detection limit （0.2 Pa）, fast response （〈 30 ms）, and excellent stability for more than 10,000 loading/unloading cycles. Based on these features, we demonstrated its applications in detecting tiny objects, sound, and human physiological signals, showing its potential in wearable electronics for health monitoring and human/machine interfaces.

Superelastic wire-shaped supercapacitor sustaining 850% tensile strain based on carbon nanotube@graphene fiber

Stretchable and flexible supercapacitors are highly desired due to their many potential applications in wearable devices. However, it is challenging to fabricate supercapacitors that can withstand large tensile strain while maintaining high performance. Herein, we report an ultra-stretchable wire-shaped supercapacitor based on carbon nanotube@graphene@MnO2 fibers wound around a superelastic core fiber. The supercapacitor can sustain tensile strain up to 850%, which is the highest value reported for this type of device to date, while maintaining stable electrochemical performance. The energy density of the supercapacitor is 3.37 mWh·cm^-3 at a power density of 54.0 mW·cm^-3. The results show that 82% of the specific capacitance is retained after 1,000 stretch-release cycles with strains of 700%, demonstrating the superior durability of the elastic supercapacitor and showcasing its potential application in ultra-stretchable flexible electronics.

High resolution non-invasive intraocular pressure monitoring by use of graphene woven fabrics on contact lens

Monitoring intracorporal pressures are important for health care and diagnosis.In this work,a contact lens tonometer employing graphene woven fabrics(GWFs),which indicate great sensibility of resistance to strain,flexibility,stretchability,transparency,and biocompatibility,is proposed for real-time monitoring intraocular pressure(IOP)with high resolution.The mechanical properties of the device during the deformation were analyzed,and the sensitivity of the fabricated device was tested on a mimic human eyeball.In vitro experiments on porcine eyes were executed to test the effectiveness of the device.The change rate of resistance under different IOP was tested.Also,the relationship between the current changes and IOP variation when keeping the voltage constant for different devices was obtained.The contact lens tonometers with GWFs as high-resolution sensing element have shown a promising prospective to realize the low-cost disposable sensing contact lens with lower power.