Expanding the applications of Utah Arrays: A neural interface for smaller nerves, the control of urination and prosthetic limbs

Today, we are implanting electrodes into many different parts of the peripheral and central nervous systems for the purpose of restoring function to people with nerve injury or disease. As technology and manufacturing continue to become more advanced, nerve electrodes are being developed to provide more selective access to multiple neurons simultaneously. With the advent of these technologies, it is important that in parallel, their potential clinical impact is investigated, so that both engineering and clinical outcomes can dictate future designs.;Three objectives were carried out to extend the applications of the Utah Slanted Electrode Array (USEAs) for use in the peripheral nervous system. The first objective was to investigate the capabilities and consequences of USEAs with four-fold higher electrode densities for use in smaller (≤ 1 mm) peripheral nerves. Chapters 2 and 3 of this dissertation cover recent work that showed USEAs with 25 electrodes/mm2 could be developed and implanted into peripheral nerves without causing global nerve injuries. Results from acute (up to 12 hr) and chronic (up to 2 mo) animal implantation studies are presented and discussed.;The second objective was to investigate the use of USEAs implanted into the pudendal nerve as a neural interface for the control of urinary function (Chapters 4-6). Utah Arrays were used to control excitation and inhibition of urinary muscles, and also to record and thereby detect, different genitourinary stimuli. Together, these results demonstrate that USEA-based pudendal nerve prostheses could provide closed-loop control and restoration of urinary function.;The final objective was to investigate the use of USEAs as a neural interface---implanted into the human median and ulnar nerves---for bidirectional control of future generation prosthetic limbs in people with upper limb amputations. More than 80 different sensory percepts could be evoked with electrical stimulation delivered to individual microelectrodes on a USEA implanted in the ulnar nerve. Recording neural activity during different perceived phantom finger movements, up to 13 different finger movements could be decoded offline. These results showed that, using USEAs, over 10 times the amount of information could be transferred to and from the nervous system than had been previously published for other peripheral nerve electrodes.;In conclusion, we have fabricated and validated a new Utah Array for use in smaller neural structures, and in parallel we have begun investigation of the clinical usefulness of USEA technologies for controlling urination and upper-limb prosthetic devices.