Research: towards biodegradable electronics… by printing squid ink

MONTREAL — Montreal researchers are trying to reduce the environmental cost of electronic components, thanks in particular to squid ink. The materials from the fishing of this mollusc could be used to imprint melanin, used as an electrical conductor.

A Quebec team has developed a process to print melanin purified from squid ink. She has just published an article in the American scientific journal “Proceedings of the National Academy of Sciences” (PNAS).

Using biosourced materials — which come from living things — in the world of electronics makes it possible to envisage a different end of life for these objects. They could then take the path of compost.

“You have to be careful, because there are criteria to respect for compostable materials, but there is a good chance that it will be biodegradable, and even biocompatible”, underlines one of the authors of the article, the Professor Clara Santato from the Department of Engineering Physics at Polytechnique Montréal.

In fact, beyond using biosourced materials, Professor Santato wants to highlight that it is possible to recover waste in electronics.

“In my opinion, we have to open our minds a little and think that waste does not exist,” she explains. Waste is just one stage in the life history of a material.”

If squid ink, which contains a lot of melanin, was used for the study, other perspectives are possible. For example, in the food industry, an insect farm contacted her to find out if their residues, rich in melanin, could be used to manufacture electronic components.

Although it has been known for about forty years that organic molecules can conduct electricity, environmental concerns have led researchers to take an interest in biosourced materials, which could be found in waste in particular, according to the teacher.

“This material (the waste) is already available, so I don’t need to go to a chemical industry to synthesize it,” she adds.

A recipe for conductivity

Another reason why melanins, brown-black pigments made of cycles of carbon atoms, have been little used until now: their lack of solubility, which makes the material difficult to process.

The Polytechnique team, in partnership with the Institute of Graphic Communications and Printability, has succeeded in overcoming this problem thanks to a recipe for making melanin from squid ink soluble.

Thanks to a few ingredients and a binding agent, this mixture, once printed, forms a three-dimensional conductive network which can therefore be used in electronic components.

It is the nanogranules of melanin, derived from squid ink, which make it possible to transmit electricity.

“Paradoxically, our interest in developing technologies has helped us in the fundamentals,” says Professor Santato.

Indeed, these years of work on melanins have made it possible to arrive at a discovery regarding the conductivity of organic molecules.

“It’s one of the first times that a biobased organic material transports electrons and not ions,” she explains, adding that there is no absolute first time, because research is built on knowledge previous ones.

Biodegradable sensors

“It’s not that in five years microprocessors will be organic,” says Ms. Santato. But there are plenty of applications for which we can think of moving towards something more respectful for the environment, for example, sensors in the oceans, where we cannot collect at the end of their life.

She cites in particular humidity and temperature detectors, oil loss detectors from boats. “We can’t get these sensors afterwards, so we have to design them to be degradable,” she adds.

Eventually, she thinks it will be possible to develop chemical sensors and perhaps integrated devices and circuits. It nevertheless specifies that, for functions where speed is sought, silicon and inorganic materials will always win for reasons of chemical bonds.

“In other cases, organic (materials), because they are degradable, because they are flexible, because they can be printed — not like silicon — will have their share,” she says. .

The only downside for the moment is that the binder used — poly(vinyl butyral) (PVB) — is not biodegradable. The team of researchers is nevertheless working to find an alternative that will mean that an entire electronic component based on squid ink or other biosourced materials could end its life in compost.

Other families of molecules are also studied, such as tannins for the storage of electrochemical energy and chlorophylls, which were analyzed in the 1970s and 1980s, in particular for their use in solar energy.

“We have more knowledge and sophisticated equipment in 2022 than in 1980. We manage to arrange the molecules much better than 40 years ago”, specifies the professor.

She hopes eventually that the “waste” of the forest industry, especially in Quebec, can be used to produce electronic components.

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Research: towards biodegradable electronics… by printing squid ink

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