Transparent tactile e-skin based on single-layer graphene

(Nanowerk News) In a recent paper in Advanced Functional Materials ("Energy-Autonomous, Flexible, and Transparent Tactile Skin"), researchers from the University of Glasgow present a promising approach toward the development of an energy-autonomous, flexible, and transparent tactile skin based on single-layer graphene integrated onto a photovoltaic cell.
Specifically, they demonstrated coplanar interdigitated electrodes based on single-layer graphene as transparent touch sensors.
Graphene based flexible capacitive sensors with various interdigitated patterns
Graphene based flexible capacitive sensors with various interdigitated patterns. A) Flexible graphene-on-PVC sample with an interdigitated pattern. B) Photograph of graphene-based flexible capacitive touch sensors with different geometries of interdigitated electrodes. C) Optical microscope image of the longitudinal cuts. (© Wiley-VCH Verlag) (click on image to enlarge)
The team's sensors were realized by using a low cost, dry processing technique involving transfer printing of graphene on flexible substrates, and an electronic cutting tool to shape interdigitated electrodes on single-layer graphene.
The dry method used by the researchers enables rapid, large-area, and low-cost production of micrometric patterns in graphene, while preserving its properties and at the same time preventing the use of more complex, harmful, and often costly techniques, such as optical lithography and laser cutting.
The combination of a PDMS protective layer and single-layer graphene coplanar capacitors is reported here for the first time.
This structure makes the sensor highly sensitive over a wide range of pressures, as the sensors could detect pressures up to 80 kPa and minimum pressures of 0.11 kPa with a sensitivity of 4.3 Pa-1.
As a potential application of the presented transparent tactile skin, the researchers demonstrate the integration of touch sensors on the phalanges of a bionic hand and used the touch feedback to grab soft objects in a controlled way.
Furthermore, due to the significant transparency of these sensors and their low power consumption, they demonstrated a promising alternative to replace the battery with a solar cell in the back plane of the touch sensors, leading to a new concept of energy-autonomous tactile skins for robotics, prosthetics, and wearable systems.
Michael Berger By – Michael is author of three books by the Royal Society of Chemistry:
Nano-Society: Pushing the Boundaries of Technology,
Nanotechnology: The Future is Tiny, and
Nanoengineering: The Skills and Tools Making Technology Invisible
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