Towards a button-sized 1024-site wireless cortical microstimulating array

Design and development of a micromachined 16-site wireless addressable active stimulating microprobe, called Interestim-3, based on the University of Michigan MEMS 3-D microelectrode-array technology have been discussed. Up to 64 Interestim-3 probes can be used in parallel with only 2 connections to a mutual hybrid coil in order to achieve a 1024-site intracortical microstimulating system with no trans or subcutaneous wires. 3-D microassembly of Interestim-3 probes, which is facilitated by small number of interconnects (2/probe) that also gives way to a high yield has been shown. Interestim-3 has been fabricated in the UM 3-μm 1M/2P BiCMOS process. It has four 60 μm × 3.1 mm shanks with 250μm spacing, each having four 181μm² sites. Interestim-3 circuitry has about 4200 transistors that occupy 21.2 mm² of 32.5 mm² probe back-end.