UC Santa Cruz

Microelectrodes are devices through which neural signals are obtained or delivered. The goals for designing microelectrodes are maximum selectivity (ability to select and record from a single cell) and minimum impedance. It is very important to reduce the impedance of metal microelectrodes as much as possible since the main source of noise for metal microelectrodes is thermal noise which is directly related to impedance. Signal to noise ratios are particularly important in the quality of the signal that can be received by the microelectrode.

In order to increase selectivity, small size microelectrodes are desired but as the size of the microelectrode decreases the impedance increases so fabrication of small size microelectrodes with low impedance is always a challenge.

To reduce the resistance of microelectrodes a traditional approach is electroplating them with platinum black, however the impedance of the microelectrode, using this method, is generally unstable. Creating microstructures on electrodes is another approach that has been tried before without a significant success.

This work investigates the problems with the design of microstructures and introduces a novel design and technique to fabricate microelectrodes with significantly lower impedance than traditional flat microelectrodes, yet more stability than the platinum black coating approach.