High-frequency sound waves can be used for micro and nano-manufacturing — technology often relevant to the medical, aerospace, consumer electronics, and transportation markets — a team of researchers of the Royal Melbourne Institute Technology (RMIT) University in Victoria have uncovered.
In a research paper published in May, MicroNano Research Facility director professor James Friend and his team of researchers demonstrated how sound waves can be used to control the spread of thin film fluid onto the surface of a specifically-designed chip.
The process, dubbed as "acoustowetting", works on a chip made of lithium niobate — a material capable of converting electrical energy into mechanical pressure. The surface of the chip is covered with microelectrodes before it is connected to a power source, converting the power into high-frequency sound waves. Thin film liquid is then added to the surface of the chip, and the sound waves are then used to control its flow.
The research shows that when the liquid is ultra-thin — at nano and sub-micro depths — it flows away from the high-frequency sound waves, and the flow reverses and moves towards the sound waves when it's at slightly thicker dimensions. But when the depth reaches a millimetre or more, the flow reverses again and starts to move away.
Friend said the researchers had developed a portable system for precise, fast, and unconventional micro- and nano-fabrication.
"By tuning the sound waves, we can create any pattern we want on the surface of a microchip," he said.
"Manufacturing using thin film technology currently lacks precision — structures are physically spun around to disperse the liquid and coat components with thin film.
"We've found that thin film liquid either flows towards or away from high-frequency sound waves, depending on its thickness.
"We not only discovered this phenomenon but have also unravelled the complex physics behind the process, enabling us to precisely control and direct the application of thin film liquid at a micro and nano-scale."
According to Friend, the discovery could potentially be applied to a range of applications ranging from thin film coatings for paint to wound care, and 3D printing.