Design and Fabrication of a Low-Cost Pulse Oximeter for Primary Health Care Centres in Kano State

Access to basic physiological monitoring equipment remains a persistent challenge in primary health care centres across northern Nigeria, where oxygen saturation monitoring is critical for managing respiratory and infectious diseases. This study presents the design and fabrication of a low-cost pulse oximeter prototype suitable for deployment at primary health care centres in Kano State. The device was constructed using an Arduino Uno microcontroller, a MAX30100 optical sensor, an OLED display module, and a rechargeable lithium-ion battery pack, keeping total component costs below five thousand naira. The sensor module operates on the photoplethysmography principle, detecting differential absorption of red and infrared light by oxygenated and deoxygenated haemoglobin. The firmware was programmed in C++ using the Arduino IDE, implementing a moving average filter to reduce motion artifact noise in the signal. Performance validation was conducted on thirty healthy volunteers at Aminu Kano Teaching Hospital by comparing prototype readings against a certified Masimo clinical pulse oximeter as a reference standard. Bland-Altman analysis of the one hundred and eighty paired measurements showed a mean bias of 0.4 percent SpO2 and limits of agreement within plus or minus 2 percent, consistent with ISO 80601-2-61 accuracy requirements for pulse oximeters. The device demonstrated adequate battery life of eight hours per charge cycle. The study demonstrates that an affordable, locally assembled pulse oximeter can meet minimum clinical accuracy standards for primary care screening applications in resource-limited northern Nigerian settings. Keywords: pulse oximeter, photoplethysmography, low-cost device, primary health care, Kano State.