title: A study of printed spiral coils for neuroprosthetic transcranial telemetry applications.
abstract: We have explored the use of printed spiral coils (PSC's) for neuroprosthetic transcranial telemetry applications. We fabricated two-dimensional PSC's on a thin (25 microns) polyimide substrate using copper (35 microns) as a conducting material. All the coils had a fixed inner diameter of 1.0 cm. We fabricated two sets of coils. One set of coils consisted of 2- to 5-turn circular and square spiral coils and had different trace widths (W), different spacings (S) between adjacent traces, and different outer diameters. The other set of coils consisted of 5-turn circular spiral coils and had fixed inner and outer diameters but different W to S ratios. We measured loss resistances (Rs and Rp) and quality factors (Q) of these coils at different resonating frequencies in the range of 5-40 MHz. Over this frequency range, we observed that for fixed inner and outer diameters, the coil with the largest W achieved the lowest Rs and the highest Rp and Q. These electrical properties and the fact that these coils can conform to the complex convoluted cortical surface suggest that a PSC [15] can provide a viable alternative to a conventional wire-wound coil for neuroprosthetic transcranial telemetry applications.
authors.affiliation: Department of Bioengineering, University of Utah, Salt Lake City 84112, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Shah
authors.forename: R P
authors.initials: RP
authors.lastname: Phillips
authors.forename: R A
authors.initials: RA
authors.lastname: Normann
mesh_terms: D001672:Biocompatible Materials; D001766:Blindness / Q000534:rehabilitation; D003300:Copper; D004553:Electric Conductivity; D017097:Electric Impedance; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D006801:Humans; D008839:Microelectrodes; D011474:Prosthesis Design; D013686:Telemetry / Q000295:instrumentation*; D014793:Visual Cortex / Q000503:physiopathology / Q000601:surgery
chemical_list: D001672:Biocompatible Materials; D003300:Copper