An implantable flexible fiber generator without encapsulation made from differentially oxidized carbon nanotube fibers

A flexible, lightweight and biocompatible electricity device based on two carbon nanotube fibers with different oxygen contents is developed to repeatedly produced electricity in various fluids from stationary deionized water to biological fluid. Its generality, easy fabrication and light weight are demonstrated to be implanted into a mouse body to stimulate the nerve without encapsulation of the device. • A flexible, lightweight and biocompatible fiber power generator was fabricated. • The generator was based on two aligned CNT fiber with different oxygen-containing groups. • The generator repeatedly produced electricity in various fluids. • The generator was applied to stimulate the nerve without encapsulation. Stable and sustainable energy supply for wearable and implanted electronics is essential for the long-term and safe living body application. A biocompatible flexible wearable and implanted energy supply without encapsulation is urgently needed to meet the demand of body comfortability and safety. Here we report a flexible, lightweight and biocompatible fiber power generator which repeatedly produces electricity in various fluids. The generator is made from two aligned carbon nanotube (CNT) fibers by modifying them with different oxygen-containing groups. The system sustains more than 150 discharge/recovering cycles without obvious decay in specific capacitance of 8.0 F/m 2 (4.5 F/g, 2.5 × 10 6 F/m 3 ) in deionized water. The recovered electricity generation is attributed to the control of the surface coverage of reactants on aligned CNTs when immersed into water during the conversion process from chemical energy to electricity. Its generality, easy fabrication and light weight are demonstrated to be promising for various applications that are highly desired while remain challenging currently, e.g. , in a mouse body to stimulate the nerve without encapsulation of the device.