A Highly Accurate pH Detection Method for Sweat Analysis using a Printed 96-Microwell Colorimetric Sensor Array

This work reports on a facile 96-microwell paper-based colorimetric sensor array device (PCSAD) for highly accurate pH detection toward sweat analysis. Although a pH test strip has been widely used to easily visualize pH conditions with naked eyes, its accuracy to guarantee below the decimal point in pH changes has still been a concern. In contrast, the PCSAD could detect slight pH changes because of abundant chemical information by the array design. The color gradients on the PCSAD upon changing pH conditions can be rapidly recorded by a flatbed scanner. The captured digital images of the PCSAD were treated with imaging analysis, followed by extraction of color intensities for inset data. By employing the partially overlapped detectable pH ranges of pH indicators, seamless inset data was obtained. Therefore, the PCSAD successfully discriminated against slight changes in pH conditions in human sweat with high accuracy by pattern recognition methods.