Sweat has biomarkers that aid doctors in health diagnoses. Wearable sensors could be utilized to track the perspiration rate of a person and offer information regarding nervous system activity, skin, and underlying health conditions.
A biosensor developed by Huanyu “Larry” Cheng, the James L. Henderson, Jr. Memorial Associate Professor of Engineering Science and Mechanics, features superhydrophobic material that measures sweat vapor without absorbing water. Image Credit: Provided by Larry Cheng/Penn State. All Rights Reserved.
However, not all sweat is created equal, and measuring some of them with current sensors is impossible. A newly developed superhydrophobic biosensor is a diagnostic tool for detecting such types of sweat.
The newly developed sensor by Huanyu “Larry” Cheng, James L. Henderson, Jr. Memorial Associate Professor of Engineering Science and Mechanics, was featured in a study reported in the ACS Nano journal.
Sensible, or liquid, perspiration is sweat that can be sensed by a person, for example, during intensive exercise. Wearable sensors could offer constant and non-invasive tracking of this kind of sweat.
Insensible, or vapor, perspiration is diverse. It is known as the loss of only water from the skin that has been secreted at a much lower rate at the time of low-intensity exercise or rest, and measuring it is hard, as per Cheng.
Monitoring insensible sweat is of high interest for evaluating skin health and disease conditions, such as eczema and wound healing, as well as underlying health statuses, such as pain or anxiety. Skin-interfaced devices that detect sweat rate and loss are currently limited to working with sensible sweat and are not suitable for insensible sweat in a vapor state.
Huanyu Cheng, Department of Engineering Science and Mechanics, The Pennsylvania State University
Cheng came up with a prototype of a superhydrophobic sweat sensor to quantify vapor from insensible perspiration. The material, a superabsorbent hydrogel composite on a porous substrate fixed between two superhydrophobic textile layers, enables the permeation of sweat vapor while preventing the sensor from being impacted by the external water droplets of sensible perspiration.
The sensor can be combined with a flexible wireless communication and powering module that helps constantly track sweat rates at various body locations.
Proof-of-concept demonstrations on human subjects showcased the feasibility to continuously evaluate the body’s thermoregulation and skin barrier functions. This enables the assessment of thermal comfort, disease conditions, and nervous system activity and provides a low-cost device platform to detect other health-relevant biomarkers in the sweat vapor as the next-generation sweat sensor for smart healthcare and personalized medicine.
Huanyu Cheng, Department of Engineering Science and Mechanics, The Pennsylvania State University
The work performed by Cheng was financially supported in part by the National Institutes of Health, the National Science Foundation, and Penn State. The National Natural Science Foundation of China, the Natural Science Foundation of Hunan Province, and the Furong Scholars of Hunan Province program provided assistance.
The co-authors of the study include Shangda Chen, Xiaofeng Li, Yujing Li, Weiyi Liu, Yangchengyi Liu, Shun Qian, Yi Sun, Yao Tian, Peihe Wang, Xiufeng Wang, Fengzhen Yang, Hanlin Yang, and Ping Zhang, all affiliated with Xiangtan University in China
Journal Reference:
Liu, Y., et al. (2023) Skin-Interfaced Superhydrophobic Insensible Sweat Sensors for Evaluating Body Thermoregulation and Skin Barrier Functions. ACS Nano. doi.org/10.1021/acsnano.2c11267.