Melt Electrowriting Ordered TPU Microfibrous Mesh for On-Demand Colorimetric Wearable Sweat Detection

Fabric-based sweat sensors based on colorimetric analysis have the characteristics of simple structure, small size, convenience, and comfort, which are more suitable for vigorous exercise. However, the realization of on-demand detection of colorimetric sweat sensors is difficult. It will be invalid immediately once the detection process is activated, which may easily lead to ineffective detection. Therefore, the design and controllable fabrication of the sweat sampling layer is the key to improving the practicality of colorimetric sweat sensors. In this article, the hydrophobic thermoplastic polyurethane (TPU) flexible microfibrous mesh was controllably constructed by melt electrowriting and used as a sweat sampling layer to realize on-demand detection of colorimetric sweat sensor. The gating of different amounts of water can be achieved by precisely and orderly depositing the TPU microfiber meshes with different pore sizes and stacking layer numbers. Simultaneously, the optimal parameters of the TPU mesh were determined by the calibration experiment of the running test, which greatly improved the use efficiency (22 times) of the colorimetric sweat sensor.Moreover, the stability of the optimal sweat sensor was improved by 418% compared with the unoptimized one. The comfort and applicability of wearable sweat sensors in vigorous sports can be enhanced greatly by the controllable preparation of the TPU flexible microfiber meshes, which is helpful to promote the development of sweat sensors.