A $5 smart blood pressure system

The burden of hypertension-related illness is greatest in lowresource settings. Barriers to its treatment include limited access to accurate Blood Pressure (BP) monitors, data on variation of BP readings over time, and training on how and when to take reliable BP readings. We developed an affordable smartphone-based BP monitor that records the pressure signal from a standard manually-inflated armband cuff, through a small low-power circuit board. The values can be stored in the smartphone or sent to a web-based electronic medical record system. The accuracy of the device was assessed by comparing the estimated BP values against the values obtained from two reference Omron devices collected from 40 healthy subjects using an in-house protocol. Over 80% of the resulting estimates were within 5 mmHg from the reference systolic and diastolic BP, and within 5 beats/min from the reference heart rate values. These preliminary results demonstrate that our affordable BP monitor can produce accurate estimates.