University of Tokyo: The president’s lab, dedicated to the ocean

President Fujii said he was deeply inspired watching Apollo 11 touch down on the Moon on TV when he was a child. While exploration of the Moon has progressed since then, he became fascinated with another “unknown” world, that of the deep seas, and decided to pursue the area of ocean engineering. Whereas the mainstream method of oceanic research has been to go out on a research vessel, collect water samples and bring them back for study, Fujii has adopted a slightly different approach, which involves transporting equipment to the deep sea by an underwater vehicle and studying the ocean on site.

“Bringing samples back to a place with different water pressure and temperature tends to change the condition of the samples, but we don’t have to worry about this if we can analyze them at the site where they were collected. Doing so also provides the benefit of being able to move on to the next survey point immediately based on the analysis results. For example, if a water body has a high manganese ion content, detailed investigation of the surrounding area may reveal hydrothermal activity,” said Kinoshita.

In fact, the Fujii Laboratory discovered new hydrothermal activity off the coast of Okinawa in 2010. The quantitative manganese ion analyzer mounted on a remotely operated vehicle was instrumental in this discovery. The analyzer is designed to detect manganese ions with a sensor by adding a reagent to seawater collected at a deep-sea site to cause a chemiluminescent reaction. At the heart of the system is a microfluidic device, which was conceived by Fujii when he was working at RIKEN. The device is capable of manipulating trace amounts of liquid in microchannels. In the world of a few hundred microns, surface tension and viscous forces act more strongly than inertial and gravitational forces, enabling fluid manipulation that would otherwise be difficult to achieve on a macroscopic scale. The conventional fluid manipulation was mainly done by carving fine grooves into glass, but it turned out that flow channels could be mass-produced inexpensively using molds with microstructures and silicone rubber. This was when a new trend of microfluidic devices began to sweep across the world.

“The smaller the device, the better when it comes to transporting probes to the deep sea, which is an extreme environment. Fujii was very insightful in focusing on the deep sea to apply microfluidic devices,” said Kinoshita.

While developing devices to detect genes in microorganisms and ATP analyzers to observe traces of living organisms, the Fujii Laboratory began to apply its research to the biomedical field with the arrival of a French researcher in the laboratory. For example, they used microfluidic devices to culture cells. Unlike petri dishes, microfluidic devices allow partial manipulation in terms of time and space, which is a major advantage in being able to freely control the cell culture environment. Medical-engineering collaborations eventually grew into one of the pillars of the laboratory’s deep-sea expertise in fluid control, including pumps and valves.