People with serious asthma already know to avoid certain activities or situations, but even then, attacks can still occur. That's why scientists at North Carolina State University are developing a wearable early warning system known as the Health and Environmental Tracker (HET). Consisting mainly of a wristband and chest patch, the technology monitors patients' bodies and their environment, sending an alert when an attack may be imminent.

The adhesive chest patch tracks the wearer's movements, heart rate, respiratory rate and blood oxygenation, plus it also monitors wheezing sounds in their lungs. While the wristband likewise detects motion, heart rate and blood oxygen levels, it's more concerned with tracking environmental factors such as airborne volatile organic compounds and ozone, along with ambient humidity and temperature.

Combined with lung-function readings from a non-wearable spirometer (which the patient breathes into several times a day), data from the two devices is wirelessly transmitted to a smartphone, where it's analyzed by an app. If it's determined that an attack is likely to occur, the patient is warned so that they can take action such as ceasing their current activity.

While similar systems have been developed before, HET has at least one key difference – it may ultimately be powered by the wearer's movements and body heat.

"The uniqueness of this work is not simply the integration of various sensors in wearable form factors," says research team member Prof. Veena Misra. "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."

Human trials of the system are expected to take place in the next few months. A paper on the research was published this week in the IEEE Journal of Biomedical and Health Informatics.

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