Soft Silicone Electrode Nets: implantable technology for visceral organ neural interfacing and functional evaluation

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Abstract Visceral organs present unique challenges to studying functional physiology and neural control. Visceral organs are often surrounded by a nerve plexus that provides distributed innervation along the organ surface and contain autonomic ganglia that can modulate function locally. Given this complexity, creating functional maps of visceral organ innervation is challenging. Another challenge is measuring organ state itself. This is significantly exacerbated by the fact that many of these organs are soft, elastic, and undergo large volume changes. In this proposal, we will develop soft silicone electrode nets compatible with these unique challenges and that can envelop visceral organs and deploy high-resolution electrodes to arbitrary positions on the organ surface. This approach is based on a 3D printed silicone electrode technology. These electrode nets will be augmented with strain gauge sensors and electrical impedance tomography electrodes to monitor physiological organ state. Ultimately, this new class of devices will 1) be intrinsically soft and elastic to allow conformation with visceral organs that undergo large volume changes, 2) integrate organ state sensors based on strain gauges and electrical impedance tomography, 3) prevent delamination issues typically associated with other thin film electrode manufacturing processes, and 4) allow rapid customization to cost-effectively transition to any organ system in animals or humans. This technology is based on materials that have a history of use in biomedical implants and are therefore potentially suitable for conducting neural mapping and electrophysiological studies of human organs in vivo. We will evaluate device performance using the bladder and urethra as a model due to the challenging interface requirements (e.g. large volume changes) and potential clinical relevance. Overactive bladder and urinary incontinence affects millions of people worldwide, is associated with costs upwards of $60 billion each year in the United States, and leads to significant decreases in quality of life. Electrode nets will be tested in acute cat experiments where we will determine the electrode-tissue mechanical stability, evaluate embedded sensor performance, and develop functional neural maps of the surface of the bladder and urethra. We will also validate device performance in a series of chronic animal experiments where device performance will be monitored for up to four months post-implant. An important feature of this enabling technology and associated manufacturing process is that these devices will be able to be quickly and cost-effectively redesigned to study other visceral organ systems including the stomach, intestines, and colon across a range of animal models as well as humans.