Ingenious inventions from Mikio Fukuhara

Curiosity can lead to some amazing breakthroughs. Our partner 福原幹雄 of Tohoku University in Japan is a scientist in S-SAFE but his inquisitiveness knows no bounds. As a boy, he was captivated by the animals around him and the workings of the universe and an avid science reader. When he saw geckos running freely across walls and ceilings, he wanted to understand how their feet stick in place. 

After reading a paper by American biologist Dr. Kellar Autumn, he understood that geckos use electrostatic forces known as van der Walls forces to cling to surfaces on a molecular level. Fukuhara noted that both the geckos’ pads and even the smoothest of surfaces have nano-scale bumps. When they come together, the protruding sections with negative charge fit easily into the positively charged recessed sections. The electrostatic forces take over and hold the connection in place. When this nanoscale electrical bond is repeated billions of times across the surface area, it becomes strong enough to overcome gravity.

Fukuhara wondered if these effects could be harnessed in a new type of battery capable of storing electricity. He first looked for a battery that could replicate the nanoscale bumps on its surface and built and tested a battery made of titanium dioxide. It stored electricity for 37 milliseconds. After reviewing his initial data, he discovered that the finer the bump size, the more electricity can be stored.  

He began looking for a new battery material with just the right tiny roughness on its surface. Fukuhara found cellulose nanofiber, an organic matter made of wood. Its intricately interwoven strands proved the perfect material for storing electricity. Fukuhara and his team sandwiched sheets of cellulose nanofiber in between aluminum electrodes to make a simple battery for testing. When connected to an electrical circuit with voltage applied, the battery charged for 50 seconds. 

The cellulose nanofiber made from wood retained an electrical charge. Moreover, the team found it can store over 100 times more electricity than titanium dioxide. The breakthrough has led to exciting new possibilities. Fukuhara is now working with a paper company with the aims of building solar-powered battery chargers and even powering flying drones by the year 2025.

Watch this video from NHK to learn more about Professor Fukuhara's exciting discovery and how it works.