The design and functionality of extremely flexible, foldable, and rollable microsupercapacitors (MSCs) with in-plane interdigital electrodes that consist of single-walled carbon nanotube (SWCNT) networks on an ultrathin polyimide substrate are demonstrated through experiments and finite element simulations. The all-solid-state MSCs can be reversibly bent, folded, and rolled purely elastically without degradation of their electrical performance. The simulation results confirm that the deformation in bent, folded, and rolled MSCs is purely elastic. The high power density (1125 W cm^–3) and small time constant (1 ms) of the present MSCs are comparable to those of aluminum electrolytic capacitors. The MSCs operate at scan rates of up to 1000 V s^–1, are characterized by a volumetric capacitance of 18 F cm^–3 and an energy density of 1.6 mWh cm^–3, and exhibit superior electrochemical stability with 96% capacity retention even after 100,000 charge/discharge cycles. The developed MSCs demonstrate high potential for integration in flexible and wearable electronic systems.

Prototyping of nanoporous carbon membranes with three-dimensional microscale patterns is significant for integration of such multifunctional materials into various miniaturized systems. Incorporating nano material synthesis into microelectronics technology, we present a novel approach to direct prototyping of carbon membranes with highly nanoporous structures inside. Membranes with significant thicknesses (1 ~ 40 μm) are rapidly prototyped at wafer level by combining nano templating method with readily available microfabrication techniques, which include photolithography, high-temperature annealing and etching. In particular, the high-surface-area membranes are specified as three-dimensional electrodes for micro supercapacitors and show high performance compared to reported ones. Improvements in scalability, compatibility and cost make the general strategy promising for batch fabrication of operational on-chip devices or full integration of three-dimensional nanoporous membranes with existing micro systems.

This paper reports a novel ultraviolet (UV) photodetector based on a TiO ₂ /graphene hybrid, with high responsivity (0.482 A W ⁻¹ ) at 3 V bias and 330 nm irradiation, which is ~100 times higher than that based on pure TiO ₂ . The collaboration of TiO ₂ and graphene in the hybrid material contributes to the high performance of the device. To be more specific, graphene provides a large surface area to load sufficient TiO ₂ nanoparticles, and the generated electrons are instantly collected due to the prominent electrical properties of graphene which can overcome the low quantum efficiency of pristine TiO ₂ caused by recombination of photo-induced electron–hole pairs. The device was fabricated on a flexible substrate using a facile spraying method that shows the possibility of broadening the future of photodetectors in wearable devices. An on-board interface circuit based on commercial IC components is implemented to collaborate with the photodetector to demonstrate a UV sensing application.