Portable Colorimetric Device with Commercial Microplates for Quantitative Detection of Urine Biomarkers: Design, Development, and Clinical Evaluation

Abstract

Urine biomarkers are important in monitoring diseases related to human kidney function. The current processes for measuring biomarker levels in urine samples require patients to regularly visit clinical facilities, which is inconvenient and sometimes impossible for patients in rural areas. Therefore, portable analysis devices for the measurement of urine biomarkers are urgently requested. In this study, a portable platform using colorimetry, a common and simple-to-operate chemical analysis technique, was developed to measure urine biomarkers. The device, using commercial test kits as recognising reagents and a 96-well microplate as a solution container, provides quantitative measures of biomarker concentration. Moreover, the proposed device introduces a calibration method to minimise the dependence of regular maintenance. The device's performance was evaluated with urine from 73 renal patients and its results matched with clinical results well. The device has the potential for measuring urine creatinine, in addition to performing a variety of commercial assays for biomarker detection in human body fluids in general.

Keywords: clinical evaluation; colorimetric sensing; portable medical device; rural areas; urine biomarkers.

Figure 1

(A,B) The sketch of a 96-well microplate colorimetry prototype; and (C) a white 96-well microplate image taken by a Raspberry Pi camera in the proposed device (Dark squares are four reference points for image process).

Figure 2

The Raspberry Pi SONY IMX219 camera RGB sensitivity and the absorption wavelength of the creatinine and glucose.

Figure 3

The 96-well microplates with the example of creatinine solutions. (A) The sketch of the 96-WM with the standards in wells A (1–8) and the testing solution in other wells; (B) An image of the creatinine solutions taken by the Raspberry Pi camera in the proposed colorimetry device.

Figure 4

The unknown testing samples (red dot) are illustrated in the graphs of the standards from (A,B) glucose and (C,D) creatinine commercial test reagents, operated by (A,C) a microplate reader and (B,D) the developed device.

Figure 5

Comparison of creatinine concentrations measured by device and obtained from SA Pathology for 73 urine samples. The biggest variation is in sample 37, which has a strong intensity in the background colour. Standard deviation is for two replicate samples.