A soft and conformable health monitor can broadcast electrocardiogram (ECG), heart rate, respiratory rate, and motion activity data as much as 15 meters to a portable recording device such as a smartphone or tablet computer. The electronics are mounted on a stretchable substrate and connected to gold, skinlike electrodes through printed connectors that can stretch with the medical film in which they are embedded.
Because the device conforms to the skin, it avoids signal issues that can be created by the motion of the typical metal-gel electrodes across the skin. The device can even obtain accurate signals from a person who is walking, running, or climbing stairs.
Continuous evaluation with a wireless health monitor could help clinicians identify trends earlier, potentially facilitating intervention before a condition progresses. Used in the home, a wearable monitor might detect changes that would not otherwise be apparent. In clinical settings, the wireless device could allow children to feel less tethered to equipment.
The monitor uses three gold electrodes embedded in the film, which also contains the electronic processing equipment. The entire health monitor is just 3" in diameter and a more advanced version under development will be half that size. The wireless monitor is now powered by a small rechargeable battery but future versions may replace the battery with an external radio-frequency charging system.
The monitor could be worn for multiple days or as long as two weeks. The membrane is waterproof, so an adult could take a shower while wearing it. After use, the electronic components can be recycled. Two versions of the monitor have been developed: One is based on medical tape and designed for short-term use in a hospital or other care facility, while the other uses a soft elastomer medical film approved for use in wound care. The latter can remain on the skin longer.
The devices do not require a gel to pick up signals from the skin. There is nothing between the skin and the ultrathin sensor, so it is comfortable to wear. Because the monitor can be worn for long periods of time, it can provide a long-term record of ECG data helpful to understanding potential heart problems. If an abnormality is detected, it can be reported wirelessly through a smartphone or other connected device.
Fabrication of the monitor’s circuitry uses thin-film, mesh-like patterns of copper that can flex with the soft substrate. The chips are the only part not flexible but they are mounted on the strain-isolated soft substrate instead of a traditional plastic circuit board.
Researchers plan to reduce the size of the device and add features to measure other health-related parameters such as temperature, blood oxygen, and blood pressure.