Salivary uric acid sensor using the fordable “Finger-Powered” microfluidic device

Here, we report a novel biosensing system using a finger-powered microfluidic device, which is suitable for daily self-testing of uric acid in saliva. To realize the rapid determination of salivary uric acid, the biosensing system measures directly from the paper-based saliva sampling device. The microfluidic device has the diaphragm pump, the reagent reservoir, and the reaction cell in which the electrochemical uric acid biosensor is embedded. Once the microfluidic chip has been folded, the finger-powered microfluidic device prepares the reagent containing the saliva, which is ready to measure. A wireless potentiostat for electrochemical measurement of uric acid with the biosensor was also developed. Combining these elements together, the whole process from saliva sampling to determination was completed in less than a minute (Sensitivity: 0.03 nA/μM). The measurement results were also consistent with that measured using a commercially available uric acid determination kit. Hence, our method is expected to have the potential to enhance the use of biochemical information in the field of healthcare IoT.