Yi Zuo
Yi Zuo

From the light and frothy foam atop a cold glass of chocolate egg cream to the warm pillowy feel of buttery pancakes, bubbles provide the textures that delight our senses. Sadly, they never last long. But the elusive goal of making bubbles last longer may have just received a boost from researchers at the University of Hawaiʻi at Mānoa. Professor Yi Zuo and his team at the College of Engineering have developed a novel experimental platform that can be used to aid in a wide range of applications.

Bubbles tend to destabilize rapidly—shrinking, bursting or merging. When the bubbles and droplets in food and materials (e.g. beer, ice cream, wet cement, foam insulation, etc.) destabilize, it alters their texture, and weakens the product’s quality.

The researchers used interfacial rheology, which measures the relationship between the deformation of a surface and external stresses.

Unfortunately, the existing experimental platforms used to aid in interfacial rheology are limited. They can directly control a drop’s volume but not its surface area or oscillations. Precise control of these oscillations is essential for studying surface phenomenon.

Because of limitations in experimental platforms, Zuo developed a novel arbitrary waveform generator (AWG) . The AWG can oscillate the surface area of a millimeter-sized droplet to follow any predefined waveform. In doing so, the researchers could manipulate the droplet to follow theoretical waveforms at various frequencies and amplitudes. This breakthrough allows scientists to study the interfacial rheology of surface-active substances and protein films.

The AWG requires only the smallest of samples when testing expensive chemicals or scarce biological fluids.

Because oscillating droplets and bubbles have been developed into a novel experimental platform for a wide range of analytical and biological applications such as digital microfluidics, signal encryption, thin film, smart materials, biosensors and biophysical simulations, Zuo’s invention has the potential to hasten discoveries in many fields.

Zuo’s research was supported by a National Science Foundation award of $400,000.