Voit, Walter E.
Permanent URI for this collectionhttps://hdl.handle.net/10735.1/4984
Walter Voit is an Associate Professor of Mecanical Engineering. He was a member of UTD's inaugural class of Eugene McDermott scholars in 2001 and finished his academic training with a PhD from Georgia Tech. He returned to UTD in 2010 as a member of the faculty. His research interests include:
- Shape memory polymers
- Polymer manufacturing
- Ionizing radiation
- Thermomechanical properties
- Biopolymer mechanics
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Browsing Voit, Walter E. by Subject "Brain-computer interfaces"
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Item Chronic Softening Spinal Cord Stimulation Arrays(Institute of Physics Publishing) Garcia-Sandoval, Aldo; Pal, A.; Mishra, A. M.; Sherman, Sydney; Parikh, Ankit R.; Joshi-Imre, Alexandria; Arreaga-Salas, David; Gutierrez-Heredia, Gerardo; Duran-Martinez, Adriana C.; Nathan, J.; Hosseini, Seyed Mahmoud; Carmel, J. B.; Voit, Walter E.; 0000-0003-0135-0531 (Voit, WE); Garcia-Sandoval, Aldo; Sherman, Sydney; Parikh, Ankit R.; Joshi-Imre, Alexandria; Arreaga-Salas, David; Gutierrez-Heredia, Gerardo; Duran-Martinez, Adriana C.; Hosseini, Seyed Mahmoud; Voit, Walter E.Objective. We sought to develop a cervical spinal cord stimulator for the rat that is durable, stable, and does not perturb the underlying spinal cord. Approach. We created a softening spinal cord stimulation (SCS) array made from shape memory polymer (SMP)-based flexible electronics. We developed a new photolithographic process to pattern high surface area titanium nitride (TiN) electrodes onto gold (Au) interconnects. The thiol-ene acrylate polymers are stiff at room temperature and soften following implantation into the body. Durability was measured by the duration the devices produced effective stimulation and by accelerated aging in vitro. Stability was measured by the threshold to provoke an electromyogram (EMG) muscle response and by measuring impedance using electrochemical impedance spectroscopy (EIS). In addition, spinal cord modulation of motor cortex potentials was measured. The spinal column and implanted arrays were imaged with MRI ex vivo, and histology for astrogliosis and immune reaction was performed. Main results. For durability, the design of the arrays was modified over three generations to create an array that demonstrated activity up to 29 weeks. SCS arrays showed no significant degradation over a simulated 29 week period of accelerated aging. For stability, the threshold for provoking an EMG rose in the first few weeks and then remained stable out to 16 weeks; the impedance showed a similar rise early with stability thereafter. Spinal cord stimulation strongly enhanced motor cortex potentials throughout. Upon explantation, device performance returned to pre-implant levels, indicating that biotic rather than abiotic processes were the cause of changing metrics. MRI and histology showed that softening SCS produced less tissue deformation than Parylene-C arrays. There was no significant astrogliosis or immune reaction to either type of array. Significance. Softening SCS arrays meet the needs for research-grade devices in rats and could be developed into human devices in the future.Item A Mosquito Inspired Strategy to Implant Microprobes into the Brain(Nature Publishing Group, 2018-11-05) Shoffstall, Andrew J.; Srinivasan, Suraj; Willis, Mitchell; Stiller, Allison M.; Ecker, Melanie; Voit, Walter E.; Pancrazio, Joseph J.; Capadona, Jeffrey R.; 0000-0002-0603-6683 (Ecker, M); 0000-0003-0135-0531 (Voit, WE); 0000-0001-8276-3690 (Pancrazio, JJ); Stiller, Allison M.; Ecker, Melanie; Voit, Walter E.; Pancrazio, Joseph J.Mosquitos are among the deadliest insects on the planet due to their ability to transmit diseases like malaria through their bite. In order to bite, a mosquito must insert a set of micro-sized needles through the skin to reach vascular structures. The mosquito uses a combination of mechanisms including an insertion guide to enable it to bite and feed off of larger animals. Here, we report on a biomimetic strategy inspired by the mosquito insertion guide to enable the implantation of intracortical microelectrodes into the brain. Next generation microelectrode designs leveraging ultra-small dimensions and/or flexible materials offer the promise of increased performance, but present difficulties in reliable implantation. With the biomimetic guide in place, the rate of successful microprobe insertion increased from 37.5% to 100% due to the rise in the critical buckling force of the microprobes by 3.8-fold. The prototype guides presented here provide a reproducible method to augment the insertion of small, flexible devices into the brain. In the future, similar approaches may be considered and applied to the insertion of other difficult to implant medical devices.