Flexible Vitals Sensors Made from Graphene Sensitized with Quantum Dots

At the ICFO – The Institute of Photonic Sciences, in Catalonia, Spain, researchers have come up with a way to use graphene to make flexible photodetectors to measure heart rate, blood oxygen concentration, and breathing rate. Additionally, the technology can also be used to measure UV levels coming from the Sun and to communicate the measured data from the sensor to a device such as a smartphone.

Today’s wearable pulse oximeters and heart rate monitors can be pretty bulky, as is the case with smartwatches. The bigger problem is that they’re not very accurate since they have to be placed tightly against the skin to obtain an optimal signal. Being rigid, the device interface with the skin is always going to be imperfect.

The ICFO team developed an entirely new way to make optical body sensors by integrating semiconducting quantum dots into graphene substrates, which results in a flexible material capable of measuring a wide range of light wavelengths at low power levels. Moreover, the technology doesn’t require any on-board batteries to be attached to the sensors, as the sensors can be powered directly using near-field communication technology from a nearby smartphone or other device.

The researchers demonstrated their technology in the form of a flexible bracelet that can measure vessel expansion under the skin, and therefore heart and respiration rates, as well as oxygenation levels of the blood in the vessel.

They also made a patch that sticks directly to a smartphone screen, and which measures and immediately displays the same vital signs as the bracelet when a finger is placed on it. Interestingly, the patch, being a light sensor, uses the same light to power itself and can therefore work for very long periods of time.

Dr. Stijn Goossens, co-supervisor of the study, which appears in the journal Science Advances, said that, “We have made a breakthrough by showing a flexible, wearable sensing system based on graphene light sensing components. Key was to pick the best of the rigid and flexible worlds. We used the unique benefits of flexible components for vital sign sensing and combined that with the high performance and miniaturization of conventional rigid electronic components.”

Study in journal Science Advances: Flexible graphene photodetectors for wearable fitness monitoring

More from ICFO…

Hat tip: Graphene-info…