
A world’s first: discovering the motion of microparticles confined inside egg-like particles by external electrical fields.
If we can freely change the color of our living room walls, from green today to red another day, with a flick of a switch depending on our mood... There is a young researcher studying colloidal particles with such a vision in mind. Her name is Dr. Kanako Watanabe, an assistant professor at the Department of Chemical Engineering of the Graduate School of Engineering at Tohoku University.
Assistant Professor Watanabe studies the development of materials using colloidal particles, including nanoparticles. Her research is about designing stable materials of nanoparticles. Nanoparticles have various properties such as optical, catalytic, and sensing properties, but they are unstable and difficult to handle. She says, "When we just add salt to particles in water, they become an aggregated cluster. The same thing happens even when an external force such as heat is applied, and this material has been called "a futuristic material that’s difficult to practical use”. She then has focused on egg-like particles which are a kind of hollow-structured particles. "I thought, outer shells would act as barriers to protect the nanoparticles inside. Egg-like particles had already been reported, but their shapes and sizes are very hard to control. In our research field, the uniformity of shape and size is important to ensure uniformity of function and stability,” she explains.
First, Assistant Professor Watanabe had to establish a method for creating uniform and stable egg-like particles, which she did during her senior year at the Department of Applied Chemistry, Chemical Engineering and Biomolecular Engineering of the School of Engineering at Tohoku University. She continued her research on egg-like particles in her master’s program. She discovered that when a cluster of egg-like particles is under an external stimulus such as electricity, the motion and arrangement of particles confined inside the egg-like particles change. "While it is common that properties of a single material is limited to one property, I thought we can derive a variety of properties from an assembly of egg-like particles depending on the type and intensity of the stimulus.” she says. She then started to investigate why the motion of particles inside changes under an electric stimulus.