Most commonly used as a test subject for 3D computer graphics, the Stanford Bunny has probably never turned up in a more intriguing place. This model of the bunny is tiny -- just a few micrometers across, the size of an average bacterium.
It was created by a team of physicists and chemists from Yokohama National University, Tokyo Institute of Technology, and the company C-MET to demonstrate a new type of resin that can be used to create electrodes. Currently, there are materials that can be used to create complex 3D sculptures, but there's a limitation that prevents these materials from being used in creating electronics.
Part of the electrode manufacturing process requires carbonization -- that is, baking at a temperature high enough to turn its surface into carbon. This increases the conductivity of a resin structure and increases its surface area -- but in the process, it damages the object's original shape.
This new material is a light-sensitive resin that includes a substance called Resorcinol Diglycidyl Ether (RDGE). Although this is usually used to dilute resin, it had never been used before in 3D sculpting. The team, led by chemistry graduate student Yuya Daicho, tested three different concentrations of RDGE in their resin compounds, and found that while there was still shrinkage, the resin objects managed to hold their shapes. The compound with the highest concentration of RDGE shrank the least -- just 20 percent.
"When we got the carbon bunny structure, we were very surprised," said Daicho's adviser Shoji Maruo, adding that it was exciting to see that "even with a very simple experimental structure, we could get this complicated 3D carbon microstructure."
This material has great potential as a means for creating conductive material on the cellular level, paving the way for implantable electronics. "One of the most promising applications is 3D micro-electrodes that could interface with the brain," Daicho said, pointing out that electrode arrays could be used for deep brain stimulation as a means to treat conditions such as Parkinson's, epilepsy, and depression.
"Although current micro-electrodes are simple 2D needle arrays, our method can provide complex 3D electrode arrays," he added.
The full research paper, titled "Formation of three-dimensional carbon microstructures via two-photon microfabrication and microtransfer molding," was published in the journal Optical Materials Express.