Flashy Wearable Patch Sees Under Your Skin

No batteries, no wires

heart rate patch
A movie of switching LEDs during the four color spectrometer device operation on skin.Jeonghyun Kim et al

Get ready to send your activity tracker to the junk drawer. A sticker-thin heart rate sensor makes our fitness bands look archaic.

Developed by Jeonghyun Kim and colleagues, this stretchy, removable circuit affixes to the skin and sends readings to a smart device. The patch monitors heart rate, blood oxygen level and UV radiation exposure, without a battery or wires. Instead, it uses wirelessly transmitted power, and relies on near-field communication — similar to how Android and Apple Pay work — to activate LED lights. These lights penetrate the skin and reflect back to optoelectronic sensors that send data to the nearby device.

An image of the lighting red LED of the pulse rate monitoring device mounted on skin.
An image of the lighting red LED of the pulse rate monitoring device mounted on skin.Jeonghyun Kim et al

The LEDs can be programmed to flash in sync with a pulse, and infrared-spectrum lights can correlate to blood oxygen levels or signal changes in skin color. It picks up UV radiation levels through an embedded UV-sensitive material that detects how light scatters and absorbs into the skin.

In the world of medical wearables, this could be a lightweight, non-intrusive revelation.