Wireless, wearable, and flexible electrocardiogram monitor with app data. (Credit: Kuniharu Takei)

As advances in wearable devices push the amount of information they can provide consumers, sensors increasingly must conform to the contours of the body. One approach applies the principles of kirigami to give sensors the added flexibility.

The sensor uses cuts in a film made of polyethylene terephthalate (PET) printed with silver electrodes to fit on a person’s chest to monitor his or her heart. In terms of wearability, by applying kirigami structure in a PET film, due to PET deformation and bending, the film can be stretchable, so that the film can follow skin and body movement like a bandage. Such a technique allows relatively stiff materials, like PET, to adapt to their surfaces.

The team found that the optimal size of the sensor is roughly 200 sq mm with a distance of 1.5 cm between electrodes. At that size, they were able to detect enough signal from the heart to be used in a smartphone app. The device with the sensor could accurately and reliably relay heart data across multiple people doing many types of everyday movements, such as walking or working while seated in a chair.

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