An edible electronic device made from seaweed will track your health

Tracing your healthcare with smartphones and watches is old-fashioned now because the University of Sussex researchers have developed groundbreaking fitness and healthcare monitoring technology from "edible" materials.

The Sussex team created the new health sensors, which can be worn by runners or patients to monitor heart rate and temperature, by combining natural materials such as rock salt, water, and seaweed with graphene.

As they suggest, the sensors are 100 percent biodegradable. They are more environmentally friendly than conventional rubber and plastic-based equivalents.

Electronics that may be consumed and digested could carry out various beneficial tasks inside the body. Their natural composition also places them within the emerging scientific field of edible electronics – electronic devices that are safe for a person to consume. 

It all started thanks to the COVID-19 lockdown

The researchers discovered that the sensitivity of their eco-friendly seaweed-based sensors is higher than that of current synthetic hydrogels and nanoparticles used in wearable health monitors.

On the other hand, Dr. Conor Boland, a physicist at the University of Sussex, had the idea to utilize seaweed in a health monitoring device while watching TV during the lockdown.

“I was first inspired to use seaweed in the lab after watching MasterChef during the lockdown. Seaweed, when used to thicken deserts, gives them a soft and bouncy structure – favored by vegans and vegetarians as an alternative to gelatin. It got me thinking: “what if we could do that with sensing technology?" said Dr. Boland.

Seaweed: The first and foremost insulator

Seaweed is primarily an insulator, but the researchers were able to produce an electrically conductive layer by adding a significant amount of graphene to a seaweed mixture. The film quickly absorbs water when submerged in a salt bath, forming a supple, spongy hydrogel that is electrically conductive.

The advancement has the potential to revolutionize health monitoring technology since future uses of clinical-grade wearable sensors might resemble a second skin or a temporary tattoo: lightweight, easy to apply, and safe due to their all-natural ingredients. This would vastly improve the entire patient experience while eliminating the need for more regularly used and potentially intrusive hospital tools, wires, and leads.

“At the University of Sussex, we are committed to protecting the future of the planet through sustainability research, expertise, and innovation. What’s so exciting about this development from Dr. Conor Boland and his team is that it manages to be all at once truly sustainable, affordable, and highly effective – out-performing synthetic alternatives," expressed Dr. Sue Baxter, Director of Innovation and Business Partnerships at the University of Sussex.

The study was published in ACS Sustainable Chemistry&Engineering on January 25.

Study abstract:

There is a societal need for electronic materials to meet sustainability standards to facilitate the creation of easily disposed of green devices. Commonly, polymer-based materials applied to create strain-sensing devices utilize hazardous solvents and nonrecyclable resources that are unsuitable for these goals. Here, we demonstrate a simple system based on food-grade algae that we mix with a pristine, aqueous graphene suspension to create nanocomposite films that were processed into biodegradable hydrogels, again using food-based culinary products. We report our hydrogels to have record low Young’s moduli of ∼0.6 Pa for a nanocomposite and record high gauge factors of G ∼ 50 for a hydrogel system. Our sustainable graphene algae hydrogels were so sensitive that they could measure an object just 2 mg in mass, equivalent to a single rain droplet, impacting their surface.