A mixed-coordination electron trapping-enabled high-precision touch-sensitive screen for wearable devices

Abstract

Touch-sensitive screens are crucial components of wearable devices. Materials such as reduced graphene oxide (rGO), carbon nanotubes (CNTs), and graphene offer promising solutions for flexible touch-sensitive screens. However, when stacked with flexible substrates to form multilayered capacitive touching sensors, these materials often suffer from substrate delamination in response to deformation; this is due to the materials having different Young’s modulus values. Delamination results in failure to offer accurate touch screen recognition. In this work, we demonstrate an induced charge-based mutual capacitive touching sensor capable of high-precision touch sensing. This is enabled by electron trapping and polarization effects related to mixed-coordinated bonding between copper nanoparticles and vertically grown graphene nanosheets. Here, we used an electron cyclotron resonance system to directly fabricate graphene–metal nanofilms (GMNFs) using carbon and copper, which are firmly adhered to flexible substrates. After being subjected to 3000 bending actions, we observed almost no change in touch sensitivity. The screen interaction system, which has a signal-to-noise ratio of 41.16 dB and resolution of 650 dpi, was tested using a handwritten Chinese character recognition trial and achieved an accuracy of 94.82%. Taken together, these results show the promise of touch-sensitive screens that use directly fabricated GMNFs for wearable devices.

Graphic abstract