10-year effort leads to the ‘wearable doctor’

Article By : R. Colin Johnson

Researchers hope that, eventually, most any chronic malady can be similarly addressed by such sensor studded wearables powered by energy harvested from the patients' own body.

An attempt to pair a wrist-worn wearable with a chest patch and a handheld breath analysis unit is coming to fruition. The decade-long development effort, which involved as many as 40 researchers, will monitor a patient's health and the environment simultaneously.

The wearable Health and Environmental Tracker (HET) aims to anticipate, for instance, an oncoming asthma attack and recommend immediate action to thwart the event. Researchers hope that, eventually, most any chronic malady can be similarly addressed by such sensor studded wearables powered by energy harvested from the patients' own body. To address this issue, the National Science Foundation (NSF) is funding the Advanced Self-Powered Systems of Integrated Sensors and Technologies (Assist) project with up to $40 million.

__Figure 1:__ *The prototype three-piece sensor pods connect together to wrap around the wrist of the patient to monitor movement, heart rate, respiratory rate, the amount of oxygen in the blood, skin impedance and wheezing in the lungs. (Source: NCSU)*

"This study for the NSF's Assist is going to be powered by the patient's own body, to monitor their health as well as the environment," principal investigator professor Alper Bozkurt told EE Times. Bozkurt, however, credits his doctoral candidate James Dieffenderfer at the North Carolina State University (NCSU, Raleigh) for most of the work done to realise the HET.

__Figure 2:__ *The first prototype of the Health and Environmental Tracker (HET) chest patch is larger and thicker than the final model due to be commercialised circa 2020. Photo credit: James Dieffenderfer (Source: NCSU)*

The HET project, now in its fourth of 10 years, recently came out of the closet with its first functional prototype which it plans to begin human trials with later this year, starting with asthma. The work is being done at the National Science Foundation’s Nanosystems Engineering Research Center for ASSIST at North Carolina State University.

"We are targeting asthma attacks first, in cooperation with partners at the University of North Carolina (UNC, Chappel Hill)," Bozlurt said. "The Environmental Protection Agency told us the correct wellness and environmental-parameters we needed to monitor in order to anticipate asthma attacks."

Consequently, Bozlurt, Dieffenderfer and associates split the functionality between a wrist worn sensor hub, a chest-adhering patch and a handheld breathalyser. The wristband focuses largely on environmental factors, monitoring volatile organic compounds and ozone in the air, as well as ambient humidity and temperature (the wristband also includes additional sensors to monitor motion, heart rate, and blood oxygen levels), then transmits collected data wirelessly to medical professionals. The patch includes sensors that track a patient’s movement, heart rate, respiratory rate, the amount of oxygen in the blood, skin impedance and wheezing in the lungs. And the handheld breathalyser—called a spirometer—measures lung function.

Once the conditions for an imminent asthma attack are determined during clinical trials, a specialised cost reduced version can be produced. In the event that different things stimulate asthma attacks in different people, personalised versions will be created. Initial experiments will be done in controlled environments with industrial partners who want to use the technology in future products.

__Figure 3:__ *Researchers James Dieffenderfer (left) and Eric Beppler work with the Health and Environmental Tracker (HET) wristband. (Source: NCSU)*

"There hasn't been a system this small and comprehensive to make such a study yet," Bozkurt said. "Our aim is to find the universal stimuli that work with all people with a particular condition, but this will need some validation."

When the project first started, the team tried to use off-the- shelf-components, but quickly found out that they could not meet the energy budget of a self-powered energy harvesting device under a milliwatt without inventing new types of sensors. In fact, the project has already won one award for its energy harvesting spirometer which contains a tiny electricity generator that is driven by the user blowing their breath into it, thus powering the device. Dieffenderfer won a Center for Integration of Medicine & Innovative Technology award for his energy harvesting spirometer. The $150,000 award will be used by Dieffenderfer to develop and market his innovative energy-harvesting health devices to consumers.

Human trials will begin this year, with a target of developing a completely self-powered commercial version circa 2020. The plan is to transmit the data from the wearable health monitor to the user's smartphone where it can be sent to doctors, as well as evaluated on-the-spot to issue warnings to users as well as strategies for heading off health crises, such as an asthma attack, before it happens.

For all the details read Low Power Wearable Systems for Continuous Monitoring of Environment and Health for Chronic Respiratory Disease published in the IEEE Journal of Biomedical and Health Informatics.

Other contributors to the project include NCSU professor Henry Goodello and undergraduate Brinnae Bent. Researchers from the University of North Carolina include professors Veena Misra, Omer Oralkan and Yong Zhu, along with postdoc research associate Bongmook Lee, doctoral candidates Steven Mills, Michael McKnight, Shanshan Yao, Jason Strohmaier, John Muth, Alper Bozkurt and Feiyan Lin plus undergrade Eric Beppler and medical doctor David Peden.

Subscribe to Newsletter