Soft, Epidermal Systems for Clinical Diagnostics

Abstract

Advancements in digital health and manufacturing technologies have enabled the development of wearable systems that can monitor various physiological parameters and biomarkers in a non-invasive and comfortable way. Through the integration of soft, flexible materials, these systems can be seamlessly deployed on the skin, allowing for imperceptible and comfortable monitoring of health conditions. This paper presents several novel strategies and has led to significant advancements in the development of soft, epidermal systems.One novel contribution of this work is the use of skin-interfaced wearable systems with integrated microfluidic structures and sensing capabilities for sweat monitoring from natural physiological processes. The introduction of 3D printing has also established a unique class of epidermal microfluidic devices, such as the 'sweatainer', which facilitates the chronological collection of multiple independent sweat samples during on-body field tests with a true 3D design space for microfluidics that is inaccessible to most commercially available 3D printing machines. The development of a wearable patch-like sensor containing the accelerometer, gyroscope, and optical Photoplethysmography (PPG) sensing modules has also been shown to be a significant contribution, allowing for the 'Always-On' Imperceptible Monitoring (AIM) of heart rate. This sensor can be worn on multiple body locations, including the forearm, shank, and sacrum which are seldom discussed, and enables accurate HR estimation during a variety of intense physical activities. PPG-based heart rate algorithms containing multiple levels of motion artifact correction are also presented, using complementary motion data to minimize the effects of motion artifacts in 1-hour cyclical activities. The results demonstrate an improvement in HR estimation over commercial devices such as the Apple Watch, and set the foundation for advancing remote monitoring of physiology and activity. Overall, this research has shown that the recent advancements in digital health and manufacturing technologies have led to the development of non-invasive, comfortable, imperceptible, and wireless soft, epidermal systems that can monitor various physiological parameters and sweat biomarkers. The use of these systems has led to the collection of biometric information such as heart rate, sweat, and body motion data from healthy adults and patients undergoing cardiac rehabilitation, offering new insights into fatigue study and patient recovery assessment. This research has revealed novel insights and perspectives on the potential applications of soft, epidermal systems in medical and fitness-related domains. These findings underscore the significance of continued research in medical and fitness-related fields to further explore the capabilities and possibilities of such soft, epidermal systems.