Photo-Adjustable TiO₂-Paper as a Smart Substrate for Paper-Based Analytical Devices

Microfluidic paper-based analytical devices (μPADs) are commonly used in point-of-care testing (POCT) due to their advantages of low cost and easy operation. However, the fabrication and potential environmental pollution of μPADs are the universal and pendent concerns. In this respect, a simple and novel method is developed for preparing photo-adjustable μPADs using the photocatalytic properties of TiO₂. A superhydrophobic TiO₂-paper substrate with unique photoactivity is fabricated. The flow channels on the superhydrophobic TiO₂-paper substrate can be quickly generated and on-demand edited by a simple UV irradiation process, to fabricate various 2D and 3D μPADs for specific applications. After usage, the residual organics and biological specimens on μPADs can be easily bleached via TiO₂-assited degradation under UV or sunlight, avoiding the risk of potential environment pollution and disease transmission. The successful application of such novel substrate in the fabrication of smart and safe μPADs for sweat analysis and motion monitoring is shown.