Prototype Development of a Low-Cost Automated Blood Pressure Monitor for Community Health Workers in Sokoto State

Hypertension screening by community health workers in Sokoto State is constrained by the cost and fragility of imported automated blood pressure monitors, creating a need for affordable, locally appropriate alternatives. This study develops a prototype automated blood pressure monitor designed for use by community health workers in primary and community care settings in Sokoto State. The prototype employs an oscillometric measurement principle implemented using a custom-designed microcontroller circuit based on the STM32 microcontroller, an inflatable arm cuff, a precision pressure sensor (MPX5050), a miniature air pump, and a solenoid valve for automated inflation and controlled deflation. Signal processing firmware implements envelope detection and systolic and diastolic pressure identification from the oscillometric pressure waveform. The display interface is a 3.5-inch touchscreen LCD with large-format readout suitable for users with low literacy. The device was calibrated against a mercury sphygmomanometer reference using an automated oscillometric validation setup. Validation testing on fifty adults at a community health centre in Sokoto metropolis compared prototype readings with reference auscultatory measurements by a trained nurse. Mean differences for systolic and diastolic pressure were 2.1 mmHg and 1.7 mmHg respectively, with ninety-two percent of readings meeting the Association for the Advancement of Medical Instrumentation validation criteria. Durability testing confirmed operability after five hundred inflation-deflation cycles without performance degradation. The study recommends further clinical validation in hypertensive patients and health worker usability testing before scaled production. Keywords: blood pressure monitor, oscillometric, community health workers, low-cost prototype, Sokoto State.