According to the Centers for Disease Control and Prevention, asthma affects more than 24 million people in the United States. To deal with symptoms, asthma patients currently use inhalers, but still attacks can be debilitating.
That’s why researchers from North Carolina State University have developed an integrated, wearable system that monitors a user’s environment, heart rate and other physical attributes in an attempt to predict and prevent asthma attacks.
The system, called the Health and Environmental Tracker (HET), is comprised of a suite of new sensor devices developed by researchers from the National Science Foundation’s Nanosystems Engineering Research Center for Advanced Self-Powered Systems of Integrated Sensors and Technologies (ASSIST) at North Carolina State University.
“Our goal was to design a wearable system that could track the wellness of the subjects and in particular provide the infrastructure to predict asthma attacks, so that the users could take steps to prevent them by changing their activities or environment,” said Alper Bozkurt, assistant professor of electrical and computer engineering at NC State.
The HET system is composed of a a wristband and a patch that adheres to the chest.
The patch is made up of 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.
The wristband monitors environmental factors, monitoring volatile organic compounds and ozone in the air, as well as ambient humidity and temperature. It also includes sensors that monitor motion, heart rate and the amount of oxygen in the blood.
In addition to the two wearables, the system also has one non-wearable component: a spirometer, which patients need to breathe into multiple times a day to measure lung function.
“Right now, people with asthma are asked to use a peak flow meter to measure lung function on a day-to-day basis,” said James Dieffenderfer, lead author of the paper and a Ph.D. student in the joint biomedical engineering program at NC State and the University of North Carolina at Chapel Hill. “That information is used to inform the dosage of prescription drugs used in their inhalers.
The team developed a customized self-powered spirometer, which collects more accurate information on lung function and feeds that data into the system. Data from all of these sensors is transmitted wirelessly to a computer, where custom software collects and records the data.
“The uniqueness of this work is not simply the integration of various sensors in wearable form factors,” said Veena Misra, co-author of the paper and a professor of electrical and computer engineering at NC State. “The impact here is that we have been able to demonstrate power consumption levels that are in the sub-milliwatt levels by using nano-enabled novel sensor technologies. Comparable, existing devices have power consumption levels in the hundreds of milliwatts.
The device does not consume a lot of power, which is important because it extends the battery life on the system and will make it compatible with power that’s generated by the body, opening the doors for self-powered sensors in the near future.
“We have tested the system in the benchtop and on a limited number of human subjects for proof of concept demonstration and have confirmed that all of the sensors work, and that the system accurately compiles the data,” said Misra.
This summer the researchers will begin testing the system an a large subject population in order to identify which environmental and physiological variables are effective at predicting asthma attacks.
One the team collects that data, the center will develop software that will track user data automatically and give users advance warning of asthma attacks. That software will eventually allow users to sync the system to their smartphones and monitor their condition on-the-go.
“After these tests are completed, and the prediction software created, we are hoping that a fully functional HET system will be available,” said Bozkurt.