A high-yield microassembly structure for three-dimensional microelectrode arrays

This paper presents a practical microassembly process for three-dimensional (3-D) microelectrode arrays for recording and stimulation in the central n ervous system (CNS), Orthogonal lead transfers between the micromachined tw o-dimensional probes and a cortical surface platform are formed by attachin g gold beams on the probes to pads on the platform using wire-free ultrason ic bonding. The low profile (150 mu m) outrigger design of the probes allow s the bonding of fully assembled high-density arrays, Micromachined assembl y tools allow the formation of a full 3-D probe array within 30 min. Arrays having up to 8 x 16 shanks on 200-mu m centers have been realized and used to record cortical single units successfully. Active 3-D probe arrays cont aining on-chip CMOS signal processing circuitry have also been created usin g the microassembly approach. In addition, a dynamic insertion technique ha s been explored to allow the implantation of high-density probe arrays into feline cortex at high-speed and with minimal traumatic injury.