Fabrication of Paper Microfluidics POCT Device for the Colorimetric Assay of Alkaline Phosphatase

Alkaline phosphatase (ALP) serves as an important biomarker for the diagnosis of various diseases including liver malfunction, bone diseases, breast and prostate cancers, and diabetes. This paper discusses the fabrication and testing of a paper-based Point-of-care testing (POCT) device for the colorimetric detection of alkaline phosphatase (ALP). The device was fabricated using a commercial wax printer followed by reagent casting on the patterned paper. In the presence of ALP concentration of 30 – 500 U/L, the reagent paranitrophenylphosphate (PNPP) changes to yellow color with increasing intensity. The different color intensities observed for different ALP concentrations were captured and a color band was developed for the visual interpretation. The RGB and HSV of the captured color intensities were processed using MATLAB to obtain the corresponding ALP concentration.