Researchers at MIT and the Technical University of Munich have developed a glucose fuel cell, which can power miniature implants inside the human body such as pacemakers. The fuel cells can withstand extreme temperatures and are only 400 nanometers thick. Original models of the fuel cell were made up of polymers. However, polymers are unable to stay intact under high temperatures, making it difficult to use in the human body. This made the researchers turn to ceramics as the main material in the middle layer of the fuel cell.