Flexible Printed Circuit Board (fPCB) Neural Probes for Monitoring Neural Signals

Neural activity monitoring in the central nervous system often utilizes silicon-based micro electro mechanical systems (MEMS) probes. Despite their strength in monitoring ant stimulating capabilities, these probes are fragile due to the brittle nature of silicon materials limiting their application in various fields. Here, we introduce flexible printed circuit board (fPCB) neural probes that have robust mechanical and electrical properties. The probes fabricated via a roll-to-roll process on films with thickness of 3.5 µm and 10 µm line width of electrodes exhibit an impedance of approximately 1.5 MΩ, reducing to about 120 KΩ after typical platinum colloidal coating. This impedance range is suitable for multiunit recordings, enabling simultaneous monitoring of a large population of neurons in the brain. The probes are mechanically very flexible and thus shows no fracture or mechanical/electrical failure under repeated bending test of up to 500 times, and also in the course of handling and monitoring. Furthermore, it is thermally stable that can endure the properties up to 175 degree Celsius and also chemically stable under acidic/alkaline condition that make possible to modify the electrodes easily under harsh conditions such as CVD (chemical vapor deposition) or electro-deposition. In fact, any mechanical failures, or degradation of monitoring capabilities has not been observed in the courses of modification. It indicates that the fPCB probes can be used as a “DO IT YOURSELF” type chronic, tailorable neural probes for chronic neural signal monitoring.<br/><br/>Keywords: flexible neural probe, modification, monitoring of neural systems, chronic