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 selfclosing, and do not require suturing for attachment to a nerve. The cuffs are carefully unrolled, a gold film deposited, and a plasmadeposited, 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.