On the April 13th, Hanyang University announced that the co-research team of Hanyang University Professors Kim Sun-jung and Jang Yong-woo of Department of Biomedical Engineering developed the "Body Insertable Supercapacitor" based on the principle of cells storing energy. The technology can be used for the next generation body energy charging system, which will eliminate the need of periodical surgery to replace batteries when it is used in heart pacemakers.

The supercapacitor is an energy saving device that uses the charging phenomenon caused by simple ion movements between the electrode and electrolyte interface or surface chemical reactions. Compared to the normal supercapacitor, the new supercapacitor can store dozens of times more energy per unit area as well as has outstanding characteristics of quick charging and semi-permanence compared to the lituium-ion battery. However, a problem of biocompatibility could occur when the supercapacity is used for the body with metallic oxide in order to improve its performance.

The co-research team found an answer to the problem in the mitochondria of the cells. Mitochondria are organelles that generate and store energy needed by cells, and NADs (Nicotinamide adenine dinucleotide) are essential biomolecules that store electrons produced in this process and transfer them to the electron transport system of mitochondria to generate ATP (Adenosine triphosphate) energy. 

The co-research team observed the process of mitochondria receiving electrons through the NAD biomolecule. Implementing this process, they put NAD biomolecules inside the carbon nanotube yarn that has high electrical conductivity, and improved the performance of the supercapaticor that the carbon nanotube yarn has more than 12 times. 

Since the biomolecule was used, this developed supercapacitor can save electricity by using electrolytes in the bioenvironment and has the advantage of high biocompatibility. In addition, becuase it has been created in a fiberous form, it can be used easily in areas such as the internal organs of bodies.

In the following in vivo experiments, when the NAD carbon nanotube yarn was inserted into the body of experimental mice, it showed the performance of a normal supercapacitor. Even after two weeks of insertion, it maintained 70% of the original performance level and was confirmed that it did not cause any immune reaction.

The research is assessed as having great significance in creating a turning point for the development of bioenergy self-powered modules and in vitro charging systems for implanted medical devices.

Professor Kim Sun-jung said, "it was a great hardship to find material that meets biocompatibility for the performance improvement of bio-insertable supercapacitors, and we discovered the answer with the energy saving system of the cells within our body." He further explained that this is a "splendid achievement in the field of bioengineering."

The result of this research (Implantable Biosupercapacitor Inspired by the Cellular Redox System) was posted on the 2nd of this month, on the online page of a world-renowned journal of chemical field, Angewandte Chemie.