A smartphone integrated paper (SIP)-based platform for rapid and on-site screening of urinary tract infections

Abstract

We present a smartphone integrated paper (SIP)-based system that enables accurate screening of urinary tract infections (UTIs) by directly identifying white blood cells (WBCs) in human urine samples. The SIP platform mainly consists of a paper-based capillaric filter and a smartphone-integrated fluorescence microscope. A paper filtration device allows a low-cost, simple method for selectively dying and isolating target WBCs in urine with more than 95% collection efficiency using capillary action through paper layers with several different pore sizes without extra pumps and tubes typically required for fluidic actuation in microfluidic systems. Furthermore, an integrated smartphone can be conveniently used for fluorescence imaging of the stained WBCs and microscopic analysis to rapidly provide UTI diagnostic results at the point of care without the need of bulky laboratory equipment and specialized training. The fabrication process for the SIP platform is simple and cost-effective, being beneficial for resource-limited field applications. We have experimentally demonstrated the capability of the SIP for isolation of target WBCs in a urine solution (more than 95% selectivity) using the paper capillaric filter, the effectiveness of the smartphone microscope for fluorescence imaging of urine solutions with 14.4 × magnification over a field of view of ∼12.25 mm2, the reliability of the platform’s cell counting with the 96.67% sensitivity and 100% specificity, and successful differentiation of the real urine samples between UTI patient and healthy person. The entire screening processes from filtration to quantification of WBCs in real human urine samples were rapidly completed within 10 min, showing its potential for point-of-care applications. The SIP technology provides a low-cost, rapid, and portable UTI diagnostic tool that can improve the access of accurate test results to developing areas and thus reduce suffering by speeding up therapy timelines.