The flexible sensor, ideal for use in the human body, uses laser-induced graphene to simultaneously but separately measure temperature and strain, potentially enabling better wound healing monitoring by providing clearer insights into inflammation and recovery. (Credit: Jennifer M. McCann)

A major challenge in self-powered wearable sensors for healthcare monitoring is distinguishing different signals when they occur at the same time. Researchers have addressed this issue by uncovering a new property of a sensor material, enabling the team to develop a new type of flexible sensor that can accurately measure both temperature and physical strain simultaneously but separately to more precisely pinpoint various signals.

The researchers aimed to accurately measure temperature and strain signals without cross talk by using laser-induced graphene, a two-dimensional (2D) material. Like all 2D materials including regular graphene, laser-induced graphene is one to a few atoms thick with unique properties, but with a twist. Laser-induced graphene (LIG) forms when a laser heats certain carbon-rich materials — like plastic or wood — in a way that converts their surface into a graphene structure. The laser essentially writes the graphene directly onto the material, making it a simple and scalable way to produce graphene patterns for electronics, sensors and energy devices.

Thermoelectric properties in a material refer to the ability to convert temperature differences into electrical voltage and vice versa, enabling such materials to be used for applications like energy harvesting and temperature sensing. The newly identified thermoelectric property of LIG makes it easy to separate the two sensor measurements and ideal for health care applications such as a sensor embedded in a bandage.

The sensor is highly sensitive, detecting temperature changes as small as 0.5° C. The material’s design takes advantage of the way porous graphene and thermoelectric components work together, making it nearly four times better at converting heat into electricity. The sensor can also stretch up to 45 percent, as well as conform to different shapes and surfaces, without losing function.

In addition to refining the sensor, the team is developing a wireless system that will allow people to monitor the data from the sensor remotely. This will make it possible to track important information, such as temperature or strain, in real time using smartphones or other devices.

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Topics:
Flexible Sensors Medical Patient Monitoring Sensors Wearables Wearables

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