Neural prostheses such as deep brain stimulation and cochlear implants are showing great promise for improving the quality of life for individuals with severe neurological disorders. Remarkable results, such as tremor suppression and restored hearing, obtained with simple technologies are paving the way for more advanced implantable prosthetics for treating these and many other debilitating neurological disorders. Technological advances are crucial for realizing sophisticated miniature wireless devices (microsystems), both to support fundamental science aimed at better understanding the human brain and its disorders and to treat their symptoms.

This dissertation has contributed a fully-implantable tissue interface for one of the first integrated wireless neural recording microsystems. The focus of this thesis was on advancing the front-end and its integration technologies. Three new microelectrode structures, robust signal conditioning circuitry and a compact versatile technique for microsystem integration have been developed.

Double-sided and lattice probes have been specifically engineered to address long-standing fundamental questions in neuroscience. Double-sided probes have been used to study the shielding of neuronal activity due to planar shanks for the first time with results showing evidence of improved electrode-cell coupling compared to single-sided probes. Lattice shanks are being used to study the tissue reactions to the presence of chronic indwelling probes. Initial histological results show significantly reduced tissue response in rats over a 12 week period compared to a solid shank, implying that chronic reaction is alleviated with exposed surface area reduction. The final structure, a 3-D array, is presented using a new architecture that allows easier and faster microassembly. This 64-site 3-D architecture interfaces with tissue volumes using the smallest footprint ever reported (1 mm²). The signal conditioning circuit provides higher gain (60dB), lower noise (4.8μV _rms) and lower power (50μW) in a smaller area (0.098mm²) than previous approaches. In addition, it includes bandwidth tuning, offset compensation and wireless gain programmability. Finally, a new approach to system integration replaces an area consuming platform architecture with an overlay cable. A parylene cable carrying routing lines between components is used to integrate this microsystem front-end in its most compact form.