Design of a Small, Affordable Low Intensity Focused Ultrasound Device for Vagus Nerve Stimulation

• Main Author: Bayer, Kelsey C.
• Language: EN
• Published: Purdue University 2018
• Subjects: Design|Biomedical engineering
• Online Access: http://pqdtopen.proquest.com/#viewpdf?dispub=10685305

<p> Depression is a serious public health issue that affects more than 300 million people worldwide. While there are antidepressant drugs to alleviate depressive symptoms, 10&ndash;30% of patients either do not respond or develop a tolerance to these drugs. Researchers have found a correlation between the inflammatory response and treatment-resistant depression (TRD). Blocking this inflammatory pathway with electrical vagus nerve stimulation (VNS) can reduce cytokine levels and depressive symptoms. However, placing an electrical VNS device is invasive, costly, and poses a risk to the vagus nerve. Low intensity focused ultrasound (LIFU) is a novel therapy that is able to both excite and suppress neuronal activity in neurological disorders. However, progression of this research area has been impeded by the size and price of these devices. I designed a 50 x 57 x 76 mm LIFU device that consists of a transducer, matching network, and amplification network. Next, I characterized my LIFU device with 2D intensity maps of the focused ultrasound (FUS) field. My device produced an instantaneous intensity up to 350 mW/cm². My colleagues and I applied the LIFU device on Sprague-Dawley rats (n = 12) for VNS with the primary goal of reducing the inflammatory response. Five out of the eight rats that we analyzed showed a decrease in the cytokine TNF-&alpha;. Future work will involve design improvements and more animal studies with varying stimulation parameters. As FUS technology becomes smaller we move closer to wearable devices. As FUS technology becomes more affordable more research groups will have the opportunity to employ this novel therapy to investigate the pathophysiology of neurological disorders.</p><p>