Seaweed-based edible electronics could outperform other health sensors

Salt shaker, jars of water, graphite pencil, seaweed and black hydrogel in petri dish
The algae hydrogel: made from seaweed, salt, water and graphite. Credit: University of Sussex

Seaweed is getting more attention as researchers uncover its health benefits, its use as a food source, and its value to the environment.

A group of UK researchers has combined all three assets, with a biodegradable, edible algae-based electronic health monitor.

Their sensor, made from food-grade seaweed, salt and graphene, is more sensitive than existing health monitors made out of similar, but synthetic, materials.

“I was first inspired to use seaweed in the lab after watching MasterChef during lockdown,” says Dr Conor Boland, a materials physics lecturer at the University of Sussex, UK, and corresponding author on a paper describing the sensor, published in ACS Sustainable Chemistry & Engineering.

“Seaweed, when used to thicken deserts, gives them a soft and bouncy structure – favoured by vegans and vegetarians as an alternative to gelatin. It got me thinking: ‘what if we could do that with sensing technology?’.”

The researchers mixed the seaweed (sodium alginate powder), bought from a specialty food supplier, with graphene, made from graphite flakes.

When dipped in a salt bath, the alginate absorbs water and turns into a spongy, flexible hydrogel. The graphite in the gel makes it electrically conductive, and the seaweed insulates it.

Person holds hydrogel in gloved hand
Researcher Adel Aljarid holding the flexible graphene seaweed hydrogel. Credit: University of Sussex

The researchers showed that this gel could sense pressure very effectively, making it a good candidate for monitoring things like heart rate.

“For me, one of the most exciting aspects to this development is that we have a sensor that is both fully biodegradable and highly effective,” says Boland.

“The mass production of unsustainable rubber and plastic based health technology could, ironically, pose a risk to human health through microplastics leeching into water sources as they degrade. 

“As a new parent, I see it as my responsibility to ensure my research enables the realisation of a cleaner world for all our children.”

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