A polymer neural probe with tunable flexibility

A novel polymeric material, off-stoichiometry thiol-ene-epoxy (OSTE+), has been evaluated for the fabrication of neural implants. OSTE+ is easily photo-structurable and exhibits mechanical properties suitable for stable implantation of the probe into brain tissue, while being sufficiently soft at physiological temperatures to reduce living tissue damage. The facile processing of OSTE+ allows use in applications where SU-8 or polyimide currently are the materials of choice. Uniquely, OSTE+ has a Young´s modulus of 1.9 GPa at 10 °C decreasing almost two orders of magnitude to 30 MPa at 40 °C, which can be compared to the Young´s modulus of 2.1 GPa for SU-8. We show a probe, with nine gold electrode sites, implanted into 0.5% agar at 40 °C using active cooling during the implantation.