The garment will automatically call emergency services when necessary, for example if the wearer suffers a cardiac arrest. This represents a considerable advance on the mobile phones which tell you when you're having a heart attack, as you don't have to hold the underwear in front of your heart for it to work. It also represents a step up from the current portable elctrocardiograms, as it does not require electrodes covered with electrolytic gel to be stuck to the wearer's skin. These can be uncomfortable if worn for long.

The device uses sensors woven into the fabric of the underwear. These detect electrical fluctuations on the skin, which are used to tell how rapidly and with what force the heart is beating. It also records activity and stress levels, both important factors in determining a person's risk of a heart attack. However, an obstacle for the developers is the need for software to distinguish between increased heart rates due to stress or physical activity.

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