Implantable Thin and Flexible Neural Electrode with a Plastically Deformable Fixation Element and an Integrated Temperature Transducer

A thin flexible neural electrode equipped with a novel fastening mechanism and a body temperature transducer is proposed. Sutures can be typically used to secure electrodes to the nerve. Physicians spend a lot of time and effort securing thin electrodes with sutures. Furthermore, the electrode’s fixation to the nerve can be too loose or too tight. To address these issues, a neural electrode equipped with a plastic deformation element fastening mechanism capable of attaching the electrode to the nerve without using sutures was developed. The novel neural electrode incorporates a latch for auxiliary use during fastening and a titanium wire as a plastic deformation element.The electrode is wrapped around the nerve and then fixed by folding the Ti wire. The fabricated electrode consists of a 15 µm-thick polyimide substrate, a gold pattern for electrical wiring, a thermistor whose resistance varies with temperature, and a 0.2 mm-diameter Ti wire as a plastic deformation element. The fabricated electrode has an impedance of 530 Ω at 1 kHz and a charge storage capacity of 230 µC/cm². To evaluate the long-term reliability of the thermistor passivation, the leakage current was maintained at less than 1 nA over 150 days of observation.