Particle deflection in a poly(dimethylsiloxane) microchannel using a propagating surface acoustic wave: size and...

Area of Science:

• Acoustofluidics
• Microfluidics
• Particle Manipulation

Background:

• Microfluidic devices are crucial for precise fluid handling at the microscale.
• Acoustic waves offer label-free methods for manipulating microparticles.

Purpose of the Study:

• To investigate the effect of propagating surface acoustic wave (PSAW) frequency on particle deflection in microfluidic channels.
• To determine the relationship between particle size, acoustic frequency, and actuation.
• To establish a criterion for particle deflection based on acoustic parameters.

Main Methods:

• Utilizing microfluidic channels to study particle behavior.
• Applying propagating surface acoustic waves (PSAWs) at various frequencies.
• Analyzing particle deflection and migration patterns in response to acoustic actuation.
• Characterizing particle response using the parameter κ = k · r, where k is the wavenumber and r is the particle radius.

Main Results:

• Particle deflection is critically dependent on both PSAW frequency and particle size.
• Larger particles are deflected perpendicular to flow at fixed frequencies, while smaller particles follow streamlines.
• Increasing PSAW frequency above a size-dependent limit actuates smaller particles.
• A critical value κc ≅ 1.28 ± 0.20 was identified for the onset of particle deflection.

Conclusions:

• Propagating surface acoustic waves (PSAWs) provide a tunable method for microparticle manipulation in microfluidics.
• The study establishes a quantitative relationship (κc) for predicting particle actuation based on size and acoustic properties.
• The demonstrated microfluidic device shows potential for effective particle separation applications.