Sangwoo Shin, an assistant professor in the Mechanical Engineering Department, took first place at the inaugural Falling Walls competition at the University of Hawaii (  He won a trip to Berlin to compete in the prestigious international Falling Walls Conference where 100 scientists present their novel ideas that can change the world.


Shin said, of his experience in Berlin, that “It was surely an extraordinary experience that was different from typical academic conferences in many ways. In brief, the conference is a 3-minute pitch-your-idea competition where every speakers are the local competition winners from all over the world. 3 minutes x 100 speakers means a non-stop, rapid firing idea pitch for 5 hours. The atmosphere is extremely fast-paced and energetic. The jury is a diverse selection of established people from various fields and sectors, from the first (French) female astronaut to a Nobel laureate.


Of 100 talks, there were many interesting and creative ideas that seemed to have a substantial impact to the society. Examples include immediate identification of various mosquitos for preventing disease transmission, purifying water using solar power, wheelchairs operated by brainwaves, just to name a few. The conference provides a venue for creative, enthusiastic people from various places in various fields to naturally mingle and share their ideas that ultimately leads to generation of new ideas. I particularly encourage senior undergrads and graduate students to participate in the competition as the environment is very young and energetic.”


Reproduced below is his presentation which you can also view on YouTube


For many of us sitting here, water is taken for granted. Clean drinking water is always within reach, so we hardly get to think about how a fresh cup of water is brought to us.


In fact, only a tiny fraction, less than 0.001%, of water on this planet can be consumed without the need of any treatment. The majority of water is in the form of non-drinkable water, which contains lots of harmful particles, including bacteria and viruses.


Currently we use porous membrane filters to remove such particles in order to produce drinkable water. The problem with membrane-based water filtration is that the filtered particles will be eventually left behind on the membrane surface. This results in increased pumping energy and is the main reason why you have to replace your filter periodically, which limits the continuous operation and increases the capital cost.


To overcome this problem, we have come up with a solution to remove particles from dirty water without using any porous membranes, but just by using CO2.


When water is exposed to CO2, CO2 naturally dissolves in water, which is the well-known process for making fizzy drinks. But what’s less known is that when CO2 is dissolved, a small electricity is spontaneously generated. This electricity is actually strong enough to push away any suspended particles.


We can use this principle to achieve continuous flow water filtration that does not require any porous membranes or high energy pumps.


Suppose dirty water, full of particles is flowing continuously along a channel. Then, simply by exposing the water to CO2 on one side, the particles will be pushed away. We can then simply remove the particles by splitting the flow.


Here you can see that it really works; you can remove tiny suspended particles continuously without the need of any membranes just by using CO2. Because this device does not require any porous membranes, it is essentially free from maintenance, and the pumping energy is significantly lower than that of the membrane-based technologies. So that is how we use CO2 for breaking the wall of water treatment. Thank you.