Diamond-on-Polymer Microelectrode Arrays Fabricated Using a Chemical Release Transfer Process

This paper reports the design, fabrication, and characterization of diamond-on-polymer microelectrode arrays. A “diamond-first” chemical release transfer process was implemented to integrate diamond electrodes, grown at temperatures >; 700 °C, on a temperature-sensitive polynorbornene-based (PNB) substrate, allowing for the advantageous neural interfacing properties of diamond to be utilized in a flexible device. Intracortical probes with two electrodes and peripheral nerve electrode arrays with ten electrodes ranging in area from 800 to 41 000 μm² were fabricated. Mechanical testing showed that the structures were flexible, with the composite structure having mechanical characteristics similar to bare PNB. Electrical testing confirmed that ohmic contacts were formed without a postanneal step and determined a diamond-on-polymer electrode impedance of ~ 1.5 MΩ at 1 kHz.