Could glucose also power medical implants? Engineers from the Massachusetts Institute of Technology in the United States and the Technical University of Munich in Germany have given the answer in the affirmative. They designed a new type of glucose fuel cell that converts glucose directly into electricity. The device is only 400 nanometers thick, about 1/100 the diameter of a human hair. The sugar-based power source produces about 43 microwatts of electricity per square centimeter, achieving the highest power density for a glucose fuel cell to date.
The new battery can withstand temperatures as high as 600°C, according to a paper published recently in Advanced Materials. If embedded in medical implants, fuel cells can remain stable during the high-temperature sterilization process required for implanted devices. The core of the battery is made of ceramic, a material that maintains its electrochemical properties even at high temperatures and at the microscale. The researchers envision that the new design could be made into an ultra-thin film, or coating, and wrapped around the implant, using the body's abundant glucose to passively power electronics.
In the new study, the researchers designed a glucose fuel cell with an electrolyte made of ceria, a ceramic material with high ionic conductivity and high mechanical strength that makes it widely used as a hydrogen fuel The electrolyte of the battery, which has been shown to be biocompatible.
The research team sandwiched an electrolyte with an anode and cathode made of platinum, a stable material that readily reacts with glucose. They fabricated 150 individual glucose fuel cells on a chip, each about 400 nanometers thin and 300 micrometers wide (about the width of 30 human hairs). The team patterned the cells onto silicon wafers, and experiments showed that the cells could be paired with common semiconductor materials. They then measured the current the battery produced when a glucose solution was passed through each wafer in a custom test station.
The team found that many of the cells produced peak voltages of around 80 millivolts. Given the small size of each cell, this output is the highest power density of any existing glucose fuel cell design.
"This is the first time that proton conduction in an electroceramic material has been used for glucose-to-energy conversion, defining a new type of electrochemistry," said the researchers. "It extends materials from hydrogen fuel cells to new and exciting The new battery uses ceramics that are nontoxic, inexpensive, and inert to both in vivo conditions and pre-implantation sterilization conditions, thus opening a new avenue for implanted sensors and other functional miniature power sources.
