All-in-one membrane micro-supercapacitors for implantable devices

The integration of energy storage devices into a single design is crucial for achieving a stable and efficient energy supply for implantable electronic devices that are compatible with soft human organs and tissues. Here we present a novel approach to fabricate all-in-one flexible energy storage devices based on phase inversion engineering of plastic polyethersulfone membrane. This method is simple, controllable, and highly scalable, and the membrane devices have no extra separator and electrolyte. Furthermore, one can effectively control the membrane structure, hydrophilicity, mechanical property, and electrochemical performance by regulating the content and kinds of active material, additives amount, and device thickness. The obtained all-in-one supercapacitor is very thin and light, with a mass of only 6.3 mg per 1.2 x 1.2 x 0.01 cm3, and applied in an opening-up system within a body fluid environment with good electrochemical performance (3.01 F cm-3 at 0.1 A cm-3), mechanical properties (Young's modulus is similar to the biological tissue), and long-term stability (capacitance retention of 94.03% after 40, 000 cycles). This plastic polymer-based membrane device has excellent biocompatibility and can be used as power supply systems, including supercapacitors and batteries for long-life, miniaturized implantable devices.