Atomization of High Viscous Liquids Using a MEMS Vibrating Mesh With Integrated Microheater

Abstract

Aerosol generation is important for a wide range of applications including drug delivery, additive manufacturing, spray cooling, and numerous other applications. However, current aerosol generation devices often have poor droplet uniformity or are limited to low viscosity liquids ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 2 cp). This work presents the development of a Microelectromechanical systems vibrating mesh atomizer capable of atomizing higher viscosity fluids while maintaining high droplet size uniformity. The overall system consists of microfabricated silicon vibrating mesh atomizer, a piezoelectric film, and a flexible thin film microheater. The Si vibrating mesh atomizer was designed to increase atomization thresholds, while the microheater is designed to reduce liquid viscosity to meet the atomization threshold. Atomizers with varying nozzle dimensions were experimentally validated using liquids with varying viscosity and physiochemical properties, such as water, glycerol, propylene glycol, and vegetable glycerin. The microheater was designed to provide local rapid heating with low power consumption of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 1 W. The droplet size distribution results show that when fluid viscosity increases, the volume median diameter of droplets increases, and the spray angle decreases. The Si-vibrating mesh atomizer was able to atomize liquids up to 49.73 cP at room temperature compared to normal metallic vibrating mesh atomizers which have a threshold of approximately 2 cP. The integrated heater enabled atomization of liquids with viscosities as high as 111 cP with low heating ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 100 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> C). 2023-0042