Silicon chip with 30 independent glucose micro fuel cells. Photo Source: advanced Materials
The device is only 400 nanometers thick, which is about 100 times the diameter of human hair. The sugary power supply produces about 43 microwatts per square centimeter, achieving the highest power density of glucose fuel cells so far.
A recent paper published in Advanced Materials points out that the new battery can withstand temperatures as high as 600 ℃. If embedded in a medical implant, the fuel cell can remain stable during the high temperature sterilization process required for the implanted device. The core of the battery is made of ceramic, which can maintain its electrochemical properties even at high temperature and micro-scale. The researchers envision that the new design could be made into an ultrathin film or coating and wrapped around the implant, using the body's rich glucose to passively power electronic devices.
In the new study, the researchers designed a glucose fuel cell whose electrolyte is made of cerium dioxide, a ceramic material with high ionic conductivity and high mechanical strength, so it is widely used as an electrolyte for hydrogen fuel cells. it has been proved to be biocompatible.
The team sandwiched the electrolyte to anodes and cathodes made of platinum, a stable material that reacts easily with glucose. They built 150 individual glucose fuel cells on a chip, each about 400 nanometers thin and 300 microns wide (about the width of 30 human hairs). The team imitates the battery pattern on a silicon wafer, and experiments show that the battery can be paired with common semiconductor materials. They then measured the current generated by the battery as it flowed glucose solution through each chip at a custom test station.
The team found that many batteries produce a peak voltage of about 80 millivolts. Given the small size of each cell, the output is already the highest power density in any existing glucose fuel cell design.
"this is the first time that proton conduction in electroceramics has been used for glucose-to-energy conversion, defining a new type of electrochemistry," the researchers said. It extends the material from hydrogen fuel cells to new and exciting glucose conversion modes. " The ceramic used in the new battery is non-toxic, cheap, and inert to in vivo conditions and pre-implantation sterilization conditions, thus opening up a new way for micro-power sources for implanted sensors and other functions.