On-demand neural probes

We demonstrate a method to vary recording site distribution on Si neural probes with a maskless finishing process. The concept is based on the use of a direct write laser (DWL) lithography on one mask layer thus enabling relatively fast on-demand processing of wafers with semicustom designs at a reasonable cost. Up till now, neural probes have only been produced with fixed standard mask sets, which is straightforward but very costly for small production volumes and inflexible for electrode distribution redesigns. Using a DWL machine enables us to selectively choose which electrodes, from a standardised electrode array, should be active. We propose a probe model with eight shafts and 64 recording electrodes distributed in 11 different ways. The process was evaluated on some of our standard Acreo neural probes, and showed as a proof of concept. Impedance characterisation was performed on active and inactive electrodes, and on electrodes with varying active area.