Implantable Biosupercapacitor Inspired by the Cellular Redox System

Abstract

The carbon nanotube (CNT) yarn supercapacitor has high potential for in vivo energy storage because it can be used in aqueous environments and stitched to inner parts of the body, such as blood vessels. The biocompatibility issue for frequently used pseudocapacitive materials, such as metal oxides, is controversial in the human body. Here, we report an implantable CNT yarn supercapacitor inspired by the cellular redox system. In all living cells, nicotinamide adenine dinucleotide (NAD) is a key redox biomolecule responsible for cellular energy transduction to produce adenosine triphosphate (ATP). Based on this redox system, CNT yarn electrodes were fabricated by inserting a twist in CNT sheets with electrochemically deposited NAD and benzoquinone for redox shuttling. Consequently, the NAD/BQ/CNT yarn electrodes exhibited the maximum area capacitance (55.73 mF cm−2) under physiological conditions, such as phosphate‐buffered saline and serum. In addition, the yarn electrodes showed a negligible loss of capacitance after 10 000 repeated charge/discharge cycles and deformation tests (bending/knotting). More importantly, NAD/BQ/CNT yarn electrodes implanted into the abdominal cavity of a rat's skin exhibited the stable in vivo electrical performance of a supercapacitor. Therefore, these findings demonstrate a redox biomolecule‐applied platform for implantable energy storage devices.

Conductive fibers for biomedical applications

“…Without additional packaging, the specific capacitance of the CNT fiber supercapacitor reached 11.4 F/g and 13 F/g in serum and blood, respectively, as well as a stable specific capacitance after 10000 cycles in phosphate buffered saline (PBS). Jang et al [ 173 ] reported an implantable CNT yarn supercapacitor based on the redox system of Nicotinamide adenine dinucleotide (NAD) in living cells. The CNT yarn electrodes exhibited a maximum area capacitance (55.73 mF/cm 2 ) in PBS and serum, and a negligible loss of capacitance after 10000 repeated charge/discharge cycles and bending/knotting deformation.…”

Bioactive Ion‐Based Switchable Supercapacitors

“…So far, there have been no reports on the use of biologically active ions such as neurotransmitters for the realization of switchable supercapacitors. Only few studies focus on the interaction of biologically active ions and porous carbon electrodes with and without electric polarization [12c,d, 13] . However, a deep understanding of electrosorption vs. physisorption mechanisms at the molecular level and the deliberate control of biologically active ion adsorption is essential for the rational design of neuromorphic interfaces and devices, neurotransmitter sensors, as well as new carriers for transmitter delivery [5–7] .…”