Portable device for the detection of colorimetric assays

In this work, a low-cost, portable device is developed to detect colorimetric assays for in-field and point-of-care (POC) analysis. The device can rapidly detect both pH values and nitrite concentrations of 5 different samples, simultaneously. After mixing samples with specific reagents, a Hi-resolution digital camera collects a picture of the sample, and a single-board computer processes the image in real time to identify the hue-saturation-value (HSV) coordinates of the image. An internal light source reduces the effect of any ambient light so the device can accurately determine the corresponding pH values or nitrite concentrations. The device was purposefully designed to be low-cost, yet versatile and the accuracy of the results have been compared to those from a conventional method. The results obtained for pH values have a mean standard deviation of 0.03 and a correlation coefficient (R) of 0.998. The detection of nitrites is between concentrations of 0.4 to 1.6mg/L with a low dete...