Carbon ‘nanobuds’ enable transparent touch sensors on 3D surfaces
The carbon nanomaterial offers numerous advantages over traditional indium tin oxide (ITO) and metal mesh structures not least that they are thermoformable, highly stretchable and can be laid down on curved and 3D surfaces.
The nanobud has a tunable electrical conductivity, high strength, low density, high thermal and mechanical stability and high electrical and thermal conductivity similar to traditional carbon nanotubes but it is not chemically inert like the carbon nanotube. The inclusion of fullerene structures provides sites of high reactivity, low work function and chemical functionalizability. In addition, they have been shown be superior field emitters than traditional nanotubes and have the added benefit that they need not be aligned for the purpose.
The company has launched CNB In-Mold Film, a stretchable, formable conductive film, optimized for use with 3D formed capacitive touch displays and touch surfaces in automobile dashboards, home appliance control panels, television remote controls, smartwatches and portable electronic devices.
This makes use of a single-step manufacturing process combining aerosol synthesis of CNB material and roll-to-roll deposition in a process Canatu calls Direct Dry Printing
CNB In-Mold Film is stretchable up to and beyond 100% and can be easily formed and back-molded using standard industrial processes such as Film Insert Molding (FIM). This means that CNB touch sensors and mechanical buttons can be produced in almost any shape, from smooth spherical domes to sharp edged casings with recesses and bulges.
"Touch has recently become the dominant user interface for tablets, smartphones and other consumer products. One of the remaining challenges for product designers is to build touch sensors into formed or back-molded plastic parts," said Erkki Soininen, vice president of marketing and sales at Canatu, in a statement. "This is especially challenging when those parts involve 3D-shaped curved surfaces. Canatu now has a solution to this design challenge. CNB In-Mold touch sensors free user-interface designers from the flat-surface paradigm, making responsive touch on 3D surfaces a reality."
The material supports local stretchability of more than 100 percent while maintaining high levels of conductivity can be laid down using industry-standard forming and injection molding processes and can laid down on industry-standard low-cost substrate materials such as polycarbonate.
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