Fabrication of G-paper devices.
(a, b) Flexible, wearable NFC bracelet deposited on silk, (c) the NFC bracelet used to open an electronic lock.
Potential applications of G-paper antennas.Replacing metal components like wires and interconnects in electronic devices could reduce production costs and waste management problems. Some metals used in electronic devices can be toxic if leached into the environment or produce air pollutants when incinerated. Lighter, cheaper, less toxic carbon-based materials make an attractive alternative.
Now a team of European researchers have developed highly flexible, highly conductive, carbon-based antennas using stacked graphene multilayers that could represent a truly competitive application for carbon-based materials in telecommunications [Scidà et al., Materials Today (2018), DOI: 10.1016/j.mattod.2018.01.007].
“We modified commercial near field communication (NFC) devices, replacing classical, all-metal antennas with new ones composed solely of carbon atoms,” explains Vincenzo Palermo of the National Research Council of Italy and Chalmers University of Technology in Sweden, who led the effort with colleagues from several European companies including STMicroelectronics.
The antennas are based on highly conductive graphene paper (G-paper), which the team fabricated by simply compressing stacks of graphene nanoplatelets. Unlike other alternative approaches, using G-paper does not require chemical etching of metals or high-temperature annealing during processing.
“Given that the properties of G-paper are different from metals, we had to tune the shape and electrical properties (resistance, inductance, and capacitance) of the carbon antennas to render them fully compatible with commercial hardware and software,” says Palermo.
Moreover, the G-paper devices can be deposited on a wide range of rigid and flexible substrates such as plastic, cardboard, paper, and even silk. Even after repeated bending, the graphene-based antennas show minimal change in resistance because individual nanoplatelets slide easily over one another without losing their strong inter-sheet electrical connection.
“The antennas can receive and transmit data with conventional mobile phones, electronic locks, and other devices, giving the approach a high technology readiness level,” Palermo told Materials Today. “We are now looking for industrial partners interested in evaluating the mass production potential of this technology.”
The antennas could be ideal for disposable electronic devices like smart cards, NFC tags or bracelets, or electronic card keys. G-paper devices have the advantage of being more corrosion resistant and thermally, chemically, and mechanically stable than their metal counterparts, opening up new opportunities in wearable electronics or biomedicine. Moreover, there is no danger of disposable devices releasing heavy metal ions into the environment during production or disposal.
“It was already known that carbon- and, in particular, graphene-based materials and coatings can be used as antennas,” points out Palermo. “But our work demonstrates that it is possible to achieve high conductivity (>105 S/m) with G-paper, not achievable up to now with standard graphene inks or coatings.”