Mechanism of particle removal by megasonic waves

Abstract

We elucidate the major mechanism of microparticle removal in the megasonic cleaning process through the direct visualization experiments. It is revealed that particles sitting on solids are removed by adjacent microbubbles that oscillate near the substrates and exert interfacial and pressure gradient forces on the particles. Other pressure and streaming effects are shown to be too weak to detach the particles.

Analysis of Cleaning Process for Several Kinds of Soil by Probability Density Functional Method

“…Recent studies on solid soil removal have focused on cleaning processes for hydrophobic and hydrophilic solid particle soils adhered to fabrics using surfactants 28,29 , laser cleaning of charcoal particle cellulose paper 30 , cleaning of fine particles by high speed air jet 31 , and cleaning of spherical polystyrene latex particles adhered to a silica substrate by a megasonic wave 32 . Recent studies on the mechanism of solid soil removal are related to the detachment process analyzed by Monte Carlo simulations 33 and by the quartz crystal microbalance technique 34 .…”

Transducer-Plane Streaming Patterns in Thin-Layer Acoustofluidic Devices

“…Understanding the driving mechanisms of acoustic streaming patterns within acoustofluidic devices is important in order to precisely control it for the enhancement or suppression of acoustic streaming for applications such as particle/cell manipulation [1-8], heat transfer enhancement [9][10][11][12], noncontact surface cleaning [13][14][15][16][17], microfluidic mixing [18][19][20][21][22][23][24][25][26][27], and transport enhancement [28][29][30][31][32][33][34][35].…”

“…INTRODUCTION Acoustic streaming is steady fluid motion driven by the absorption of acoustic energy due to the interaction of acoustic waves with the fluid medium or its solid boundaries. Understanding the driving mechanisms of acoustic streaming patterns within acoustofluidic devices is important in order to precisely control it for the enhancement or suppression of acoustic streaming for applications such as particle/cell manipulation [1-8], heat transfer enhancement [9-12], noncontact surface cleaning [13][14][15][16][17], microfluidic mixing [18][19][20][21][22][23][24][25][26][27], and transport enhancement [28][29][30][31][32][33][34][35].In most bulk micro-acoustofluidic particle and cell manipulation systems of interest, the acoustic streaming fields are dominated by boundary-driven streaming [36], which is associated with acoustic dissipation in the viscous boundary layer [37]. Theoretical work on boundary-driven streaming was initiated by Rayleigh [38], and developed by a series of modifications for particular cases [39][40][41][42][43][44], which have paved the fundamental understanding of acoustic streaming flows.…”

Damage-free Design of Megasonic Waveguide for Single Wafer Process

“…In the case of cleaning of patterned wafers, the megasonic field provides an oscillating acoustic pressure that is known to enhance mass diffusion and convection in the trench. High power densities, however, limit the use of megasonic cleaning in patterned wafers due to the significant level of damage of the patterned structures [7][8][9][10][11][12].…”