Design and evaluation of wearable device for early detection of hypertension

Abstract

Hypertension remains a major public health burden globally and is a leading contributor to cardiovascular disease-related morbidity and mortality, particularly in low- and middle-income countries such as Uganda. Early detection and continuous monitoring of blood pressure are critical in reducing the incidence of hypertension-related complications. However, resource-constrained healthcare systems face significant barriers including limited access to functional diagnostic equipment, shortage of trained personnel, and high costs associated with conventional ambulatory monitoring solutions. In response to this unmet clinical need, a team of final-year biomedical engineering students at Makerere University designed, developed, and evaluated a low-cost, wearable blood pressure monitoring device for early detection of hypertension. The device was developed using the Stanford Biodesign innovation framework and the Double Diamond design model. These methodologies enabled a structured, iterative approach—from problem identification and concept generation to prototyping, validation, and redesign. The final solution is a wrist-worn device utilizing photoplethysmography (PPG) technology to estimate blood pressure non-invasively, integrated with a digital signal processor and an energy-efficient 32-bit ARM microcontroller for real-time analysis and display. Initial testing phases focused on verifying clinical performance criteria, including accuracy, precision, and firmware stability. While the prototype showed promise, the results highlighted critical limitations in signal noise handling, calibration inconsistencies, and algorithmic bias, particularly under variable physiological and environmental conditions. Based on these findings, a comprehensive redesign was implemented—introducing Kalman filtering for improved signal processing, enhanced sensor positioning for consistency, firmware logic optimization, and miniaturized hardware to improve comfort and wearability. Subsequent validation of the redesigned prototype demonstrated measurable improvements in measurement consistency, usability, and operational reliability. Nonetheless, some deviations from reference standards persisted, particularly in extreme systolic and diastolic ranges, indicating that additional clinical validation and algorithm refinement are necessary before regulatory approval and mass deployment.