inkjet printer

Inkjet-compatible conductive ink lets users make their own electronics at home

Image credit: DT

Conductive ink that can be used in standard inkjet printers could pave the way to flexible energy storage components, such as supercapacitors, that could be created in any size or shape.

Researchers from Drexel University in the USA and Trinity College Dublin in Ireland created the ink from a highly conductive type of two-dimensional material called MXene.

Conductive inks are already being used to make the radio-frequency identification (RFID) tags used in highway toll transponders, circuit boards in portable electronics and to line car windows as embedded radio antennas and to aid defrosting.

But for the technology to see broader use, conductive inks need to become more conductive and more easily applied to a range of surfaces, the researchers said.

Researcher Yury Gogotsi suggests that the ink created in Drexel’s Nanomaterials Institute is a significant advancement on both of these fronts.

“So far only limited success has been achieved with conductive inks in both fine-resolution printing and high-charge storage devices,” Gogotsi said. “But our findings show that all-MXene printed micro-supercapacitors, made with an advanced inkjet printer, are an order of magnitude greater than existing energy storage devices made from other conductive inks.”

While researchers are steadily figuring out ways to make inks from new, more conductive materials, like nanoparticle silver, graphene and gallium, the challenge remains incorporating them seamlessly into manufacturing processes.

“For most other nano inks, an additive is required to hold the particles together and allow for high-quality printing. Because of this, after printing, an additional step is required - usually a thermal or chemical treatment - to remove that additive,” explains researcher Babak Anasori.

“For MXene printing, we only use MXene in water or MXene in an organic solution to make the ink. This means it can dry without any additional steps.”

MXenes are a type of carbon-based, two-dimensional layered materials, created at Drexel in 2011, that have the unique ability to mix with liquids, like water and other organic solvents, while retaining their conductive properties.

Because of this, Drexel researchers have produced and tested them in a variety of forms, from conductive clay to a coating for electromagnetic interference shielding to a near-invisible wireless antenna.

Adjusting the concentration to create ink for use in a commercial printer was a matter of time and iteration. The solvent and MXene concentration in the ink can be adjusted to suit different kinds of printers.

“If we really want to take advantage of any technology at a large scale and have it ready for public use, it has to become very simple and done in one step,” Anasori said. “An inkjet printer can be found in just about every house, so we knew if we could make the proper ink, it would be feasible that anyone could make future electronics and devices.”

MXene ink was put to the test in a series of printouts, including a simple circuit, a micro-supercapacitor and some text, on substrates ranging from paper to plastic to glass.

They found they could print lines of consistent thickness and that the ink’s ability to pass an electric current varied with its thickness – both important factors in manufacturing electronics components.

“Compared to conventional manufacturing protocols, direct ink printing techniques, such as inkjet printing and extrusion printing, allow digital and additive patterning, customisation, reduction in material waste, scalability and rapid production,” Anasori said. “Now that we have produced a MXene ink that can be applied via this technique, we’re looking at a world of new opportunities to use it.”

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