Fabrication and Microassembly of a mm-Sized Floating Probe for a Distributed Wireless Neural Interface
AbstractA new class of wireless neural interfaces is under development in the form of tens to hundreds of mm-sized untethered implants, distributed across the target brain region(s). Unlike traditional interfaces that are tethered to a centralized control unit and suffer from micromotions that may damage the surrounding neural tissue, the new free-floating wireless implantable neural recording (FF-WINeR) probes will be stand-alone, directly communicating with an external interrogator. Towards development of the FF-WINeR, in this paper we describe the micromachining, microassembly, and hermetic packaging of 1-mm3 passive probes, each of which consists of a thinned micromachined silicon die with a centered Ø(diameter) 130 μm through-hole, an Ø81 μm sharpened tungsten electrode, a 7-turn gold wire-wound coil wrapped around the die, two 0201 surface mount capacitors on the die, and parylene-C/Polydimethylsiloxane (PDMS) coating. The fabricated passive probe is tested under a 3-coil inductive link to evaluate power transfer efficiency (PTE) and power delivered to a load (PDL) for feasibility assessment. The minimum PTE/PDL at 137 MHz were 0.76%/240 μW and 0.6%/191 μW in the air and lamb head medium, respectively, with coil separation of 2.8 cm and 9 kΩ receiver (Rx) loading. Six hermetically sealed probes went through wireless hermeticity testing, using a 2-coil inductive link under accelerated lifetime testing condition of 85 °C, 1 atm, and 100%RH. The mean-time-to-failure (MTTF) of the probes at 37 °C is extrapolated to be 28.7 years, which is over their lifetime. View Full-Text
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Yeon, P.; Mirbozorgi, S.A.; Ash, B.; Eckhardt, H.; Ghovanloo, M. Fabrication and Microassembly of a mm-Sized Floating Probe for a Distributed Wireless Neural Interface. Micromachines 2016, 7, 154.
Yeon P, Mirbozorgi SA, Ash B, Eckhardt H, Ghovanloo M. Fabrication and Microassembly of a mm-Sized Floating Probe for a Distributed Wireless Neural Interface. Micromachines. 2016; 7(9):154.Chicago/Turabian Style
Yeon, Pyungwoo; Mirbozorgi, S. A.; Ash, Bruce; Eckhardt, Helmut; Ghovanloo, Maysam. 2016. "Fabrication and Microassembly of a mm-Sized Floating Probe for a Distributed Wireless Neural Interface." Micromachines 7, no. 9: 154.
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