Grants We Funded

Abstract
There are over 1.7 million people within the United States currently suffering from some type of limb loss, and this number continues to grow by 185,000 each year. Newer prostheses to restore lost function use the patient's remaining muscle groups to control and increase the utility of these replacement limbs. The current state of the art treatment allows subjects to have the greatest restoration of function through targeted reinnervation of pectoralis muscle groups using nerve from the amputated limb. However, these devices have limited control options for prostheses with multiple degrees of freedom and are generally difficult to master. Our team has developed a regenerative peripheral nerve interface (RPNI) that creates a biologically robust and functional connection to the nerve in an amputated limb through the use of a graft of free muscle tissue. The graft is sutured to the severed residual nerve, and electrodes are affixed allowing amplified signals to be recorded from the muscle. In our ultimate application field of a human amputated stump, up to 25 individual RPNIs will be placed within this confined space. Each of these RPNIs will require well isolated signals to be used for control of individual joints within the replacement prosthesis. To achieve fine and independent motor control, recorded signals from each RPNI need to be independent from those of nearby RPNIs connected to different motor actions. We propose to develop and analyze biosignal insulators in regenerative peripheral nerve interfaces. Preliminary data indicates that our current biological insulator, acellular small intestinal submucosa (SIS), provides less than 2% signal isolation over a range of several millimeters when used in an acute environment. By contrast, a silicone sheet provides nearly 70% isolation over the same range. Within this study, we will evaluate and compare long term signal isolation levels in RPNIs utilizing silicone or SIS biosignal insulators.

Biography
Nicholas Brandon Langhals, PhD serves as an Assistant Research Scientist in the Neuromuscular Lab within the Plastic Surgery Section of the Department of Surgery at the University of Michigan. Dr. Langhals received both his Master's of Science in Engineering as well as Doctorate of Philosophy (PhD) in biomedical engineering from the University of Michigan (Ann Arbor, MI). His Bachelor's of Science in Engineering was obtained in bioengineering from Arizona State University. Dr. Langhals has worked as a Senior Research Engineer within the Center for Neural Communication Technology, served as a consultant for Neuronexus Technologies (Ann Arbor, MI) and Biotectix (Ann Arbor, MI), and recently founded Rhythm Solutions, Inc. Dr. Langhals’ previous research efforts were focused on cortical brain-machine interfaces, cortical mapping, direct brain drug delivery, electrode development and characterization, as well as neural signal analysis. He is now applying those skills towards the development of electrode technology and signal processing techniques for neuroprosthetic, cardiac, and other electrophysiological interfaces. One of his two main efforts is focused around the development of regenerative peripheral nerve interfaces that have the potential to be used for control of replacement robotic appendages in amputees as well as for extracting control signals for wheelchairs or computer cursors. His secondary efforts are focused around the development of real-time processing strategies for mapping atrial fibrillation from intracardiac electrodes.