Solar Powered Wrist-Worn Continuous Pulse Monitoring

Achievement date: 

The National Science Foundation’s (NSF’s) Nanosystems Engineering Research Center (NERC) for Advanced Self-Powered Systems of Integrated Sensors and Technologies (ASSIST) has developed a wireless, solar-powered, wrist-worn platform – called SoliBand – for continuous monitoring of correlated physiological and environmental parameters during the activities of daily life. This initial demonstration proves the capability to produce photoplethysmogram (PPG) signals – measurements of human pulse pressure – using commercially available off-the-shelf integrated circuits (ICs). A collaborative effort is underway between North Carolina State University (NC State) and Penn State University to further improve the charge storage capacity of the on-board super-capacitor where an initial five-fold increase has already been obtained.

SoliBand is a first effort at creating a self-powered, wrist-worn health and environmental monitoring device capable of obtaining and correlating physiological and environmental parameters with high statistical significance. This device will create large volumes of data through continuous and wireless acquisition to create opportunities for correlative studies. PPG is a common diagnostic and wellness tracking parameter that can be obtained using relatively few electronic components; its low cost and non-invasiveness have made it the subject of studies showing correlation to parameters such as heart rate and cardiac cycle; arterial aging; abnormal decrease or increase in body blood volume (hypo-/hyper-volemia); and, decrease in systolic blood pressure (often indicative of intradialytic hypotension or IDH).

The SoliBand can be thought of as three systems interconnected wirelessly: a wrist-worn device acquires data; a smartphone receives the data for short-term storage; and the dedicated server stores the data for analysis over long sample durations.  Bluetooth Low Energy (BLE) tethers the device to a smartphone where a mobile app makes the phone an access point to a dedicated server for long-term continuous storage of data. The smartphone’s connection to the dedicated server can occur via WIFI or Mobile Network.