| Advances in neuro-medicine depend critically on supporting technologies, including those associated with penetrating microelectrodes. While these have developed from single-site microwires to three-dimensional micromachined electrode systems, several important issues remain. This research focused on the array-tissue interface, on application-specific electrode design, and on neural amplifiers for use in bidirectional microelectrode system front-ends.;Three new three-dimensional array structures were developed. A novel architecture, which enables two perpendicular probe sets, was coupled with open-scaffold shanks to create 3-D lattice arrays for bio-response investigations. These arrays have 15% of the shank area of constant-footprint solid counterparts. Chronic (8-week) in vivo studies have shown similar 2-D lattice probes significantly mitigated the tissue reaction and dramatically increased the number of adjacent (within 50mum) surviving neurons from 36% to 87%.;An innovative design for rapidly-assembled folded 3-D arrays was created, requiring only one mask beyond the standard boron-doped process. This realizes the smallest platform structure ever reported for such a device, with zero-rise above the platform top and virtually no lateral extent past the probes. Electrode and shank pitch are both 200pm on the 64-site prototype. The implanted device stands less than 350pm above the cortex and displaces only 1.7% of the instrumented area. Recordings in guinea pig cortex verified functionality.;A 160-site array for neuroscience mapping of the ventral and dorsal cochlear nucleus consisting of five-probes (3-VCN, 2-DCN) permitted high-density 3-D CN mapping and somatosensory integration studies for the first time. Multi-region stimulation (1000microm2 sites) and recording (177microm2 sites) demonstrated the efficacy of bimodal silicon arrays for investigating the biological circuits of the central nervous system and as prosthetic devices.;For electrode-electrolyte interface enhancement, iridium sites were modified with carbon nanotubes (CNTs). On non-released probes, in situ growth of vertically-aligned forests was achieved, and dip-coated sites exhibited an order-of-magnitude impedance reduction. Neural signals in guinea pig cortex were recorded with released dip-coated CNT-probes.;A new integrated neural recording amplifier, consuming only 46.5muW of power, was designed and fabricated in a 0.5mum CMOS process. The 0.026mm2 circuit has an in-band gain of 58.9dB with a tunable lower cutoff frequency and an upper cutoff frequency of 21.3kHz. |
