Continuous and Simultaneous Monitoring of Arterial and Venous Oxygenation Using Noninvasive Optical E-Tattoos

The proposed research aims to revolutionize the monitoring of blood oxygenation by developing a noninvasive, wrist-worn soft sensor patch that can capture the arterial and venous oxygenation separately and simultaneously. Traditional pulse oximeters only measure arterial oxygenation and are limited in their ability to detect metabolic abnormalities such as sepsis, which requires venous oxygenation measurements. By leveraging advanced noninvasive optical sensing technology and novel algorithms, this project seeks to create a device that overcomes these limitations. The ultrathin, stretchable, and self-adherable nature of the patch allows an array of sensors to be comfortably worn on human wrist, ensuring accurate long-term monitoring. Advanced algorithms will be created to separate arterial and venous pulses. These innovations could transform patient care by providing accessible and continuous monitoring of venous oxygenation and reducing the need for invasive procedures. Additionally, it promises to make strides in equitable healthcare, as it aims to provide precise oxygenation measurements across diverse patient populations, irrespective of skin pigmentation. This project aims to develop a novel wireless, noninvasive optical e-tattoo, which refers to lightweight, ultrathin, and skin-conformable sensor patch, capable of continuous and simultaneous monitoring of arterial and venous oxygenation. The research addresses the current unmet need for accurate noninvasive venous oxygenation measurement by isolating venous blood signals using a reflective, depth-sensitive photoplethysmography (PPG) array on a wrist-conformable e-tattoo. The proposed system integrates four key innovations: (1) development of an ultrathin, stretchable e-tattoo with an array of PPG sensors placed over major artery-vein pairs such as the radial artery and vein at the wrist; (2) design of algorithms for separating arterial and venous pulses and converting raw absorbance data into oxygenation levels; (3) validation using a dynamic optical phantom with known ground truth to ensure the accuracy and reliability of the measurements; and (4) pilot clinical validation against invasive catheter measurements. This research is expected to significantly enhance the accuracy of noninvasive venous oxygenation readings, facilitating better diagnosis and treatment of cardiometabolic abnormalities. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.