Xiaona Sun

Integration of Au Nanorods With Flexible Thin-Film Microelectrode Arrays for Improved Neural Interfaces

In neural prosthetic systems, a low-impedance electrode-tissue interface is important for maintaining signal quality for recording, as well as effective charge transfer for stimulation. However, neural microelectrodes often have high impedance due to their small surface areas. In this paper, we present a simple method of increasing their effective surface areas by introducing nanostructures on the electrode sites. The method combines photolithography and electron-beam evaporation with a locally patterned anodized porous alumina template to integrate Au-nanorod arrays on the flexible thin-film microelectrode, which can significantly increase the effective surface area and decrease impedance due to its 3-D and compact nanostructures. Moreover, the geometrical and electrical properties of Au-nanorod electrodes were demonstrated and compared with conventional planar microelectrodes by using a scanning electron microscope and an impedance spectroscopy system. Experimental results showed that approximately 25 times lower interface impedance was achieved for this nanostructured microelectrode. Such Au-nanorod integrated microelectrode arrays will be a promising tool for neural engineering.

Fabrication of dome-shaped flexible electrode arrays for retinal prostheses

In order to enable electrode sites to get closer to target neurons, obtain a better stimulation and minimize the electrochemical erosion of electrode, we proposed dome-shaped flexible neural microelectrode arrays (MEAs) for neural applications. With the use of photosensitive polyimide (Durimide 7510, PI) as substrate, a flexible microelectrode with 6 × 6 array of dome-shaped electrode sites was fabricated by combining photolithography and metal patterning with electroplating process. An evaluation of the dome-shaped electrode was also performed by simulation, SEM and impedance test. Experimental results showed, compared with conventional planar microelectrodes with the same base area, the 3D dome-shaped microelectrodes exhibited an 80% decrease in electrode impedance. The dome-shaped electrodes produce more uniform current distribution than the 3D pyramid-shaped microelectrode, which is helpful for its long-term safety of stimulation.