Atomization of High-Viscosity Fluids for Aromatherapy Using Micro-heaters for Heterogeneous Bubble Nucleation

Abstract

The development of a novel lead-free microelectromechanical-system (MEMS)-based atomizer using the principle of thermal bubble actuation is presented. It is a low-cost, lead-free design that is environmentally friendly and harmless to humans. It has been tested to be applicable over a wide range of fluid viscosities, ranging from 1 cP (e.g., water) to 200 cP (e.g., oil-like fluid) at room temperature, a range that is difficult to achieve using ordinary atomizers. The results demonstrate that the average power consumption of the atomizer is approximately 1 W with an atomization rate of 0.1 to 0.3 mg of deionized (DI) water per cycle. The relationships between the micro-heater track width and the track gap, the size of the micro-cavities and the nucleation energy were studied to obtain an optimal atomizer design. The particle image velocimetry (PIV) results indicate that the diameter of the ejected droplets ranges from 30 to 90 μm with a speed of 20 to 340 mm/s. In addition, different modes of spraying are reported for the first time. It is envisioned that the successful development of this MEMS-based atomizing technology will revolutionize the existing market for atomizers and could also benefit different industries, particularly in applications involving viscous fluids.

Cavitation is the determining mechanism for the atomization of high-viscosity liquid

“… 47 , 48 , 49 In addition, gene therapy medications are DNA and mRNA molecules wrapped with polymers, peptide chains, and lipids in the outer layer; therefore, the viscosity of the medication is higher than 10 cP. Currently, the viscosity for the atomization of high-viscosity liquids is usually reduced by heating, 50 but the high temperature tends to denature the medication and is therefore unsuitable for biomedical applications. 51 our team has proposed a two-dimensional vibration-coupled structure to supply high energy input to the liquid.…”

Piezoelectric atomization of liquids with dynamic viscosities up to 175 cP at room temperature

“…In 2010, A. Lozano et al used a piezoelectric ceramic disc structure to achieve ultrasonic atomization of liquids with a kinematic viscosity of 28 cSt [34] . In 2017, Junhui Law et al implanted a microheater into an atomization device to achieve atomization of liquids with viscosities of 1 cP − 200 cP, using heating to generate large amounts of gas nuclei [35] . However, heat could destroy or degrade medicines, and the design is too complex to be used in the pharmaceutical field.…”

Error Correction and Reanalysis of the Vibration Analysis of a Piezoelectric Ultrasonic Atomizer to Control Atomization Rate

“…These types of atomizers have their own advantages and disadvantages, but compared with static mesh atomizers, dynamic mesh atomizers do not need a liquid cavity with variable volume, greatly simplifying the structure and effectively solving the problems of the low energy utilization rate and large droplet size. In addition, given its advantages, such as low cost, low energy consumption, and uniform atomizing particle size, dynamic mesh atomizers have been widely used in air humidification, spray cooling, biomedicine, aromatherapy, atomizing inhalation therapy, and other fields [3][4][5][6][7][8][9][10].…”