Handheld microfluidic multiple detection device for concurrent blood urea nitrogen and creatinine ratio determination using colorimetric approach

A novel microfluidic multiple detection (MMD) platform consisting of a microfluidic chip and a self-built detection system is proposed for determining the creatinine (CRE) and blood urea nitrogen (BUN) concentrations in whole blood samples. In the proposed approach, a drop of whole blood is injected into the inlet of the microfluidic chip and filtered through strips of hemofiltration paper. The plasma enters the BUN and CRE detection chambers and is absorbed by pre-placed test strips embedded with analyte-specific reagents. Secondary reagents are then introduced into the detection chambers using a finger pump, and the chip is heated to induce Berthelot and Jaffe reactions. An image of the reaction compounds is captured by a CMOS camera and transmitted to a smartphone, where the BUN and CRE concentrations are derived from predetermined calibration curves using RGB analysis software. The proposed MMD platform is demonstrated by comparing the results obtained for 43 whole blood samples collected from patients with chronic kidney disease (CKD) and health volunteers with the measurements obtained using a traditional benchtop system. The results confirm that the proposed MMD platform offers a cost-effective, convenient, and rapid technique for BUN/CRE ratio (BCR) determination in point-of-care (POC) contexts.