Super ‐Absorbent Polymer Valves and Colorimetric Chemistries for Time‐Sequenced Discrete Sampling and Chloride Analysis of Sweat via Skin‐Mounted Soft Microfluidics

Abstract
This paper introduces super absorbent polymer valves and colorimetric sensing reagents as enabling components of soft, skin‐mounted microfluidic devices designed to capture, store, and chemically analyze sweat released from eccrine glands. The valving technology enables robust means for guiding the flow of sweat from an inlet location into a collection of isolated reservoirs, in a well‐defined sequence. Analysis in these reservoirs involves a color responsive indicator of chloride concentration with a formulation tailored to offer stable operation with sensitivity optimized for the relevant physiological range. Evaluations on human subjects with comparisons against ex situ analysis illustrate the practical utility of these advances.

A soft, skin‐mounted microfluidic device with novel differential hydrophobic and hydrophilic valves enables discrete, time‐sequenced capture, storage, and analysis of sweat. The device incorporates on‐device, real‐time chloride concentration detection using 2,4,6‐tris(2‐pyridyl)‐s‐triazine chelation chemistry. Evaluation in situ and on human subjects undergoing rigorous physical activity demonstrates the device performance and accuracy compared to clinical‐standard tools.

Source: Small - February 2, 2018 Category: Nanotechnology Authors: Sung Bong Kim, Yi Zhang, Sang Min Won, Amay J. Bandodkar, Yurina Sekine, Yeguang Xue, Jahyun Koo, Sean W. Harshman, Jennifer A. Martin, Jeong Min Park, Tyler R. Ray, Kaitlyn E. Crawford, Kyu ‐Tae Lee, Jungil Choi, Rhonda L. Pitsch, Claude C. Grigsby, Ad Tags: Full Paper Source Type: research