The Effect of the Elimination of Micromotion and Tissue Strain on Intracortical Device Performance
Abstract
The burden associated with paralysis and limb loss is disproportionately borne by Veterans. By bypassing damaged regions of the nervous system, neuroprosthetic technology offers a means for persons living with significant disability to live a more independent and complete life. For any such technology, the therapeutic value relies on the extent to which it is both robust and reliable. It is well known that brain-machine interfaces based on intracortical probes can be used to record brain signals to control paralyzed or robotic prosthetic limbs. However, this technology is neither reliable nor robust, in part because these devices are made of extremely stiff materials -- 1 million times stiffer than the surrounding brain tissue. This difference in stiffness is believed to create inflammation, which degrades the brain tissue and leads to device failure. It has been proposed that intracortical probes that are flexible enough to move with the brain would exhibit an improved tissue response, and more importantly, enhanced device performance. However, to date, there have been no definitive studies that test the impact of device stiffness alone as a factor in intracortical probe tissue response and recording efficacy. Several prior studies have considered more flexible materials than silicon although none have used materials that approach the inherent flexibility of living brain tissue. The proposed study brings together experts from neuroprosthetics and materials science to capitalize on shape memory polymers (SMPs). Intracortical probes will be fabricated from these new materials, which have the capacity to dynamically change their stiffness based on their surrounding environment. These novel SMP-based probes are initially stiff to permit insertion into the brain; then, in the presence of physiological body temperatures, the devices can soften to levels approaching the stiffness of the surrounding brain tissue. Importantly, we can tune the degree of stiffness such that we can definitively address a fundamental question that limits progress in the field: Does probe softening improve the surrounding tissue response and recording performance of the device? Our preliminary data demonstrate feasibility of both of the core aims of the proposal and show that functional SMP-based intracortical probes are feasible and behave under chronically implanted conditions. While the short-term impact will be on the scientific community through publications, presentations, and other forms of data sharing, the core technology has exceptional promise for translation into the clinic. SMP-based probes are compatible with reliable manufacturing practices and the team is poised to pursue translation.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 04, 2016
- Source ID
- W81XWH1510608
Entities
People
- Jeffrey R Capadona
Organizations
- Louis Stokes Cleveland VA Medical Center
- United States Army