Novel Monolithic Silicon Probes with Flexible Parylene Cables for Neural Prostheses

This work presents the first parylene-insulated silicon probes, which are used for neural prostheses to record high-level cognitive neural signals. With parylene technology, our probes have several advantages compared with the current devices. First, instead of inorganic materials (e.g. SiO_2 and Si_3N_4), the electrodes and conduction traces on the probes are insulated by parylene, an easily-deposited polymer with mechanical flexibility and biocompatibility. As a result, the probes exhibit better electrical and mechanical properties. Second, flexible parylene cables are monolithically integrated with the probes, which arm the probes with very high flexibility to be easily assembled to a high density 3-D array and at the same time provide an ideal method to transmit neural signals through skull during chronic recording. The all dry fabrication process and an 8x2 probe array (64 electrodes) were demonstrated. The probes were successfully tested electrically and mechanically in rat and monkey cortex. Neural signals were properly recorded.