Sensor that can detect feather’s touch a boon for next-gen healthcare

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A strain sensor that can detect a feather’s touch and is touted as the “most sensitive ever” has been developed by researchers at the Materials Physics Group at the University of Sussex.

The researchers believe their sensor could bring new levels of sensitivity to wearable tech for measuring patients’ vital signs and to systems monitoring the structural integrity of buildings and bridges.

The sensor can stretch up to 80 times higher strain than strain gauges currently on the market and show resistance changes 100 times higher than the most sensitive materials in research development.

Researcher Marcus O’Mara said: “The next wave of strain-sensing technology uses elastic materials like rubber imbued with conductive materials, such as graphene or silver nanoparticles, and has been in development for over a decade now.

“We believe these sensors are a big step forward. When compared to both linear and non-linear strain sensors referenced in the scientific literature, our sensors exhibit the largest absolute change in resistance ever reported.”

Professor Alan Dalton said: “This promising technology may prove especially useful in established fields such as healthcare, sports performance monitoring and rapidly growing fields such as soft robotics.

“Our research has developed cheap, scalable health-monitoring devices that can be calibrated to measure everything from human joint motion to vitals monitoring. Multiple devices could be used across the body of a patient, connected wirelessly and communicating together to provide live, mobile health diagnostics at a fraction of the current cost.”

The researchers built the sensor by incorporating large quantities of graphene nanosheets into a structure that boasts excellent electromechanical properties. They believe their method has the potential to be extended to a wide range of two-dimensional layered materials.

Currently, commercial gauge devices suffer from relatively low sensitivity and strain range, which prevents the kind of high-strain sensing required for bodily motion monitoring.

The new sensors are able to detect incredibly small strains on the material due to tiny amounts of resistance that can be detected in the graphene layers.

They allow both high-sensitivity low-strain sensing for pulse monitoring and high-strain measurement of chest motion and joint bending as a result of the record resistance change.

Researcher Dr Sean Ogilvie said: “Commercial strain sensors, typically based on metal foil gauges, favour accuracy and reliability over sensitivity and strain range. Nanocomposites are attractive candidates for next-generation strain sensors due to their elasticity, but widespread adoption by industry has been hampered by non-linear effects such as hysteresis and creep due to the liquid-like nature of polymers at the nanoscale which makes accurate, repeatable strain readouts an ongoing challenge.

“Our sensors settle into a repeated, predictable pattern which means that we can still extract an accurate read-out of strain despite these effects.”

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