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- Title
Fabrication and Microassembly of a mm-Sized Floating Probe for a DistributedWireless Neural Interface.
- Authors
Yeon, Pyungwoo; Mirbozorgi, S. Abdollah; Ash, Bruce; Eckhardt, Helmut; Ghovanloo, Maysam
- Abstract
A 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 kO 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.
- Subjects
MICROASSEMBLING; ELECTRONIC probes; BRAIN-computer interfaces
- Publication
Micromachines, 2016, Vol 7, Issue 9, p154
- ISSN
2072-666X
- Publication type
Article
- DOI
10.3390/mi7090154