An implantable bipolar spine stimulation probe with bio-inspired adhesive microtubes

This paper presents a bipolar electrical probe for implantable nerve stimulation treatment. This probe features bio-inspired microtubes to enhance the adhesion with tissues and to extrude out a tissue adhesive. The probe has a hollow chamber to store the tissue adhesive, and the adhesive can flow outside through a seal which is dissolved when exposed to water in tissues. The probe is fabricated from a designed 4-layer flexible printed circuit (FPC) substrate. The FPC is composed of polyimide and patterned coppers layers adhered together by a glue. In addition to the electrical conduction, the copper circuit on the FPC can be used as sacrificial material for making the microtubes and the chamber. Polyurethane (PU) is used to cover the chamber, and parylene C is deposited for biocompatibility. Polyethylene glycol (PEG) is chosen to seal the microtubes due to its water solubility and biodegradability. By combining FPC structure design with post process, an adhesive implantable stimulating probe was fabricated.