Self-closing Micro-Cuff for Neural Recording in the Locust

Abstract

- We have developed a self-wrapping flexible cuff electrode for recording electrical activity on the descending contralateral movement detector (DCMD) neuron of the locust. First, a gold film is sputtered onto a monoaxially oriented polycarbonate membrane. Then, the resulting bilayer film is cut into individual strips parallel to the machine direction of the polycarbonate film. Thermally shrinking the polycarbonate at 155 0 C actuates the curl. This method can be used to fabricate controlled diameters between 50-250 µm; diameter is controlled by thickness of the two layers and the temperature and duration of the heat shrinking process. The cuffs are self-closing, and do not require suturing for attachment to a nerve. The cuffs are carefully unrolled, a gold film deposited, and a plasma-deposited, ion-sensitive resist applied. A stencil mask is then used to define the metallization lines by 50 kV He + ion beam proximity lithography. Ion milling transfers the resist pattern to the metal film. Conformality of the resist and large depth-of-field of the lithography are key to high resolution patterning on these non-flat substrates. The dielectric overcoat is a layer of exposed resist, which simplifies the opening of the contact windows, and provides excellent biocompatibility.