Free standing carbon nanotube composite bio-electrodes
Carbon nanotubes present a new material for the construction of electrodes for electrochemical devices such as batteries, capacitors, and actuators. Such electrodes require high conductivity, strength, and surface area. The latter two requirements are often incompatible. Electrodes composed entirely of carbon nanotubes (bucky paper) have high surface areas but are typically weak, and have insufficient conductivity for practical macroscopic applications. Here we report a technique that uses naturally occurring biopolymers to produce electrodes (free standing films) that exhibit conductivities of 300 S/cm. These composites also have considerable mechanical strength (up to 145 MPa) and sufficient specific capacitance of 19-27 F/g to enable them to be used as freestanding electrodes. One potential application that deserves special attention is that of biocompatible electrodes, where the binder is a biopolymer already used in a range of implants. Preliminary studies reported here show that the new carbon nanotube biopolymer electrodes can foster prolific L929 cell growth.