Fabrication of an Automated Blood Group Testing Device Using Colorimetry for Use in Rural Clinics in Ekiti State

Blood group determination is a fundamental clinical procedure required for safe blood transfusion, yet rural health clinics in Ekiti State, South West Nigeria, lack reliable access to trained laboratory technicians and commercial blood grouping equipment. This project presents the fabrication of an automated blood group testing device based on colorimetric analysis of agglutination reactions using specific blood typing reagents. Blood samples reacted with anti-A, anti-B, and anti-D reagents are placed on a microwell plate, and an array of photodiode-LED pairs measures the optical absorbance of each well. An Arduino Uno microcontroller interprets the absorbance values to determine the ABO and Rhesus blood group. A 16x2 LCD displays the determined blood group, and a thermal printer produces a hardcopy record for the patient file. The device was validated using blood samples from 80 volunteer donors at the Ekiti State Blood Transfusion Service whose blood groups had been independently confirmed by the standard tube agglutination technique. Concordance between the automated device and the reference method was 97.5 percent across all ABO groups and 96.3 percent for Rh determination. The study documents sources of discordance including weak agglutination reactions in subgroup variants. Total fabrication cost was approximately 41,000 Naira, compared to the cost of a commercial auto-analyser which exceeds 2 million Naira. This project demonstrates a locally manufacturable solution to point-of-care blood typing in resource-limited Nigerian clinical settings. Keywords: blood group testing, colorimetry, point-of-care diagnosis, rural clinic, Ekiti State