Nanowire Integrated Microelectrode Arrays for Neuroelectronic Applications

Neural prosthetic devices are artificial extensions of body parts which allow a disabled individual to restore the body functions. Electrical interface using a neuroelectronic device is the key to restore the disabled body functions. Also, in vivo monitoring of the electrical signals from multiple cells as well as from multiple locations from a single cell during nerve excitation and cell-to-cell communication are important for design and development of novel materials and methods for laboratory analysis. In-vitro biological applications such as drug screening and cell separation also require cell-based biosensors. The electrophysiological activity of certain cells such as neurons and cardiac cells are monitored using planar microelectrode arrays integrated with microfluidic devices. One of the main issues of the current microelectrode array is the difficulty in selective integration of neuronal cells due to the size dependency of its impedances. Also, this mismatch introduces large amount of noise in the interface circuit. It is quite evident that nanotechnology can solve these problems and an efficient electrical interconnection is possible using nanowires. This paper presents the design and development of planar microelectrode arrays integrated with vertically aligned nanowires for the neuroelectronic interface applications. The higher surface area densities of such nanowire integrated microelectrode arrays show promising results in impedance control. We have fabricated nanowire integrated microelectrode arrays on silicon as well as on flexible polymer substrates. High degree of specific growth can be obtained by controlling the nanowire growth parameters.