Development of stretchable optical sensors for measurement of penile hemodynamics

Project Summary/Abstract Erectile dysfunction (ED) is a progressive disease, which is often characterized by rampant fibrosis of the corpus cavernosum in severe disease states. It is hypothesized that hypoxia resulting from inadequate blood perfusion and/or depressed oxygenation is a primary driver of the fibrotic process in the corpus

cavernosum. Moreover, ischemic priapism is highly prevalent in men with sickle cell disease. In these instances, sickling of the erythrocytes obstructs venous outflow from the corporal bodies, resulting in prolonged erections with minimal inflow of new blood into the penis. This stagnation of blood in the penis results in severe

penile hypoxia despite the presence of a prolonged erection, which ultimately leads to advanced erectile function. This proposal is in response to PAR-23-119 “Catalytic Tool and Technology Development in Kidney, Urologic, and Hematologic Diseases”. Our goal is to develop a wearable device for prolonged penile oxygen

saturation monitoring that can contour to the skin of the penile shaft, that is also flexible to movement and stretchable for expansion during erection. This proposal leverages our team’s recent innovation of a stretchable optical sensor photodiode for wearable photoplethysmography. We seek to optimize and validate

this technology in rodents before advancing to testing in human patients. There are two specific aims to this proposal. Aim 1 is to design and fabricate optical sensors for rodent penile hemodynamic monitoring. Aim 2 is to determine if changes in measured oxygen saturation correspond with changes in rodent intracavernous

pressure upon erection induction. Multiple variables can influence the oxygen saturation signal attained from photoplethysmography, as well as the depth within the tissue that the signal is obtained from. Major variables include the composition of the tissue through which light must penetrate, the wavelength of light emitted from

the light source, and the light intensity emitted from the source. For this project, we will use both mice and rats due to the difference in thickness of the penile fascia, tunica albuginea, and cavernous smooth muscle and collagen through which light must penetrate and reflect off of oxygenated hemoglobin in the sinusoids. Devices

will be fabricated to form fit the mouse and rat penile shaft, with three prototypes for each that contain micro light emitting diodes that emit different wavelengths of light. Three different light intensities will be used while testing each wavelength. Variable changes in intracavernous pressure will be induced by stimulation of the

cavernous nerve with variable voltages. Additionally, both rapid and prolonged erections will be induced by intracavernous injection of sodium nitroprusside and papaverine.