A simple 3D printed microfluidic device for point-of-care analysis of urinary uric acid

Point-of-care testing (POCT) technology allows scientists to monitor and diagnose diseases at the patient site, much faster than classical lab-based methods. Herein, a rapid, simple, and sensitive 3D printed microfluidic device integrated with smartphone-based on-chip detection is described for POCT quantification of urinary uric acid. The device includes two circular inputs each connected to a microliter-scale chamber, separated by an integrated porous membrane, located between the sample and reagent chambers. The microfluidic device was fabricated from a transparent photopolymer using a 3D printer, in a single run. The concentration of uric acid was determined based on a chromogenic reaction in which ferrous ion, produced via the reduction of ferric ion by the analyte, complexed with 1,10-phenanthroline, and the color was recorded by a smartphone. Response surface methodology including a central composed design was utilized to evaluate the experimental parameters and subsequent introduction of a multivariate model to describe the experimental conditions. Under the optimum conditions, the calibration curve was linear over the concentration range of 30–600 mg L−1. The limit of detection was determined to be 10.5 mg L−1. The microfluidic device was successfully utilized for the recovery and quantification of uric acid in the urine, with recoveries ranging from 91.7 to 99.7%.