Silicon chip with 30 individual glucose micro fuel cells, seen as small silver squares inside each gray rectangle.

By Gwen Egan

The glucose fuel cell is 1/100 the diameter of a single human hair and could power miniature implants inside the human body.

What if there was a piece of ultrathin technology that was powered by sugar from the human body?

Researchers at MIT and the Technical University of Munich are answering that question with a new piece of mini tech — a tiny, yet powerful, fuel cell. 

This new and improved glucose fuel cell takes glucose absorbed from food in the human body and turns it into electricity, according to MIT News. That electricity could power small implants while also being able to withstand up to 600 degrees Celsius — or 1112 degrees Fahrenheit — and measuring just 400 nanometers thick. 

400 nanometers is around 1/100 of the diameter of a single human hair. 

Custom experimental setup used to characterize 30 glucose fuel cells in rapid sequence.  Kent Dayton

The device itself is made from ceramic, allowing it to be made at such a minuscule size and withstand ultra-hot temperatures.

With a piece of technology that thin, it could be wrapped around implants to power them while harnessing the glucose found in the body.  

“Glucose is everywhere in the body, and the idea is to harvest this readily available energy and use it to power implantable devices. In our work we show a new glucose fuel cell electrochemistry,” said Philipp Simons, who developed the design as part of his doctorate thesis.

Jennifer L.M. Rupp, Simons’ thesis supervisor, said while a battery can take up 90% of an implant’s volume, this technology would be a power source with no “volumetric footprint.”

Rupp first had the idea for the fuel cell after getting a glucose test near the end of her pregnancy. 

“In the doctor’s office, I was a very bored electrochemist, thinking what you could do with sugar and electrochemistry. Then I realized, it would be good to have a glucose-powered solid state device. And Philipp and I met over coffee and wrote out on a napkin the first drawings,” she said. 

The “basic” glucose fuel cell is made up of a top anode, a middle electrolyte, and a bottom cathode. The team at MIT looked specifically at the middle electrolyte layer in order to improve existing models of the device. 

The middle layer is usually made of polymers which can degrade at high temperatures making them difficult to use for implants that must undergo an extremely hot sterilization process. Polymers are also difficult to work with on a miniature scale.

That’s when researchers began to turn their attention toward ceramic as their star material. 

“When you think of ceramics for such a glucose fuel cell, they have the advantage of long-term stability, small scalability, and silicon chip integration. They’re hard and robust,” said Rupp. 

The specific ceramic material used is called ceria. 

“Ceria is actively studied in the cancer research community. It’s also similar to zirconia, which is used in tooth implants, and is biocompatible and safe,” said Simons. 

The researchers “have opened a new route to miniature power sources for implanted sensors and maybe other functions,” says Truls Norby, a professor of chemistry at the University of Oslo in Norway. “The ceramics used are nontoxic, cheap, and not least inert both to the conditions in the body and to conditions of sterilization prior to implantation. The concept and demonstration so far are promising indeed.”

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