A SU-8-Based Fully Integrated Biocompatible Inductively Powered Wireless Neurostimulator

A fully integrated minimally invasive compact polymer-based wireless neurostimulator was designed, fabricated, and characterized both in open air and in vivo. The neurostimulator
$(3.1 \times 1.6 \times 0.3\ \hbox{mm})$
consists of a planar spiral coil for wireless power supply through inductive coupling, two Schottky diodes for full-wave rectification, an application-specific integrated circuit neurostimulator circuit chip for stimulus spike signal generation, and two biphasic platinum–iridium (PtIr) stimulation electrodes. The device is fully integrated and completely embedded in biocompatible SU-8 packaging. For in vivo testing, the wireless neurostimulator was implanted subcutaneously in a rat hind limb. At the coupling power of 21 dBm (125 mW) at 394-MHz resonant frequency, stable and robust cortical responses during extended periods of wireless stimulation were recorded.
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[2012-0085]