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Depression is a prevalent and serious medical illness, and while there are antidepressant drugs to mitigate depressive symptoms, 10 - 30% of patients either do not respond or develop a tolerance to these medications. Literature supports that there is an interrelation between the inflammatory response and treatment-resistant depression. A promising method to tackle depressive symptoms is to block the inflammatory signaling pathway with vagus nerve stimulation (VNS), reducing pro-inflammatory cytokine levels. Although electrical VNS devices exist, they are invasive, expensive, and have side effects including voice alteration, dyspnea, and cough. Low intensity focused ultrasound (LIFU) is a promising method that can stimulate a desired region noninvasively and without long term negative side effects. Nonetheless, the existing LIFU devices can be expensive, cumbersome, and large. The Center of Implantable Devices designed a prototype called the SonicNode that incorporates a transducer, matching network, and an amplifier into a 50 mm x 57 mm x 76 mm package. We modified the transducer head and created an intensity map of the focal region to demonstrate the improved performance of the device. The SonicNode and LIFU technology can be employed for long term, noninvasive treatment of a variety of neurological disorders.

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 – 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-α. 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.

Urinary incontinence (UI) is the involuntarily urination that usually effects older people or is the result of an injury. UI affects more than eleven million people and the cost of incontinence management in the United States in 2000 was $19.5 billion. Where conventional physical therapies have failed, pelvic nerve stimulation is a promising form of regulating the bladder long term. Piezoresistive pressure sensors consist of two variable resistance values and two known resistance values that are represented on a daughterboard. This unknown resistance represents the change in pressure. The filling and voiding of the bladder was characterized through acute surgeries. It was found that the pressure sensor successfully detects changes in the bladder. Based on the collected data an implantable package can be assembled for chronic surgeries. The package consists of a bionode to record and stimulate the pelvic nerve, a powernode to apply a voltage, and a daughterboard. The next phase of the research is to thoroughly test the implantable package by placing the rat inside a cavity that will wirelessly power the device to regulate the bladder. Future applications of this will be long term use in humans with the ability to control the stimulus through a smart phone application. This research can improve the overall health and quality of life of patients by giving them back control of their bodies.