Professor James Kwan 'The humble bubble and its applications in engineering'

Nature hates bubbles. It does everything in its power to get rid of them. So, making new bubbles is always a challenge and takes a lot of work. For eons, some animals have used nature’s hatred of bubbles to their advantage by creating bubbles and relying on their inevitable violent collapse to stun or kill prey. These bubble collapses can be so violent that they can melt nearby steel surfaces, create light, and even break down water molecules. To prevent a bubble’s seemingly inevitable demise, engineers have developed methods to coat or trap bubbles. Interestingly, these bubbles quickly change in volume in response to changes in the local environmental pressure - a phenomenon known as cavitation. By introducing these exogenous bubbles as cavitation agents into a system and exposing the system to high frequency pressure waves known as ultrasound, we can provide localised changes in fluid momentum, temperature, and chemical composition. By designing the structure and modifying the material of a cavitation agent, we can further tune the local mechanical, thermal, and chemical effects from cavitation for a specific application. In this talk, I want to share how my research group is developing novel cavitation agents to tackle certain engineering challenges, specifically focusing on two applications: enhancing drug delivery and improving catalysis.