(315j) Accessing Sweat without Perspiration: The Journey Towards Exertion-Free Sweat Sampling, Management, and Sensing

Sweat is an essential biofluid for monitoring individuals’ health as it contains several key biomarkers from blood. Additionally, sweat is relatively easy to generate on-skin due to the wide distribution of sweat glands throughout the body.^[1] Conventional sweat based devices have commonly relied on active perspiration release - such as one caused by physical exertion, thermal stimulation, or iontophoresis, for accessing the biomarker information in sweat. These techniques make such devices susceptible to dilution and contamination from excess sweat amounts and be inoperative on sedentary subjects and under the conditions of low humidity. Hence, the focus of this talk will be on our two recently developed passive sweat accessing techniques that do not require external sweat presence on-skin prior testing – osmotic and diffusion-based sampling. The osmotic based sweat extraction technique utilizes a hydrogel of lower chemical potential (of water) than sweat for extraction. By combining this technique with evaporation assisted pumping, we have developed wearable patches to operate on skin for long-term (~ hours) sweat lactate monitoring.^[2,3] The diffusion-based technique relies on the natural perspiration rate of the body, which is dominant in areas with high sweat gland density, such as the fingertip. A porous hydrogel can facilitate biomarker transport from the fingertip to the transducing element, eventually allowing discrete, touch-based, and painless monitoring. For this talk we will mainly discuss how we have utilized this technique for ketone detection in sweat due to its correlation to diabetes.^[4] Overall, the successful transition of these techniques to point-of-care and wearable devices holds great potential in laying the foundation for next generation sweat based devices for personalized healthcare monitoring.

References:

[1] T. Saha, R. Del Caño, E. la De Paz, S. S. Sandhu, J. Wang, Small 2022, 2206064, 2206064.

[2] T. Saha, J. Fang, S. Mukherjee, M. D. Dickey, O. D. Velev, ACS Appl. Mater. Interfaces 2021, 13, 8071.

[3] T. Saha, T. Songkakul, C. T. Knisely, M. A. Yokus, M. A. Daniele, M. D. Dickey, A. Bozkurt, O. D. Velev, ACS Sensors 2022, 7, 2037.

[4] J. Moon, R. Del Caño, C. Moonla, K. Sakdaphetsiri, T. Saha, L. Francine Mendes, L. Yin, A. Chang, S. Seker, J. Wang, ACS Sensors 2022, 7, 3973.