Acoustic resonances in microfluidic chips: full-image micro-PIV experiments and numerical simulations

Area of Science:

• Acoustics
• Fluid Dynamics
• Microfluidics

Background:

• Acoustic radiation forces and acoustic streaming are crucial phenomena in microfluidic systems.
• Understanding these forces is key for applications in particle manipulation and mixing.
• MHz-range acoustic actuation presents unique challenges and opportunities in microfluidic research.

Purpose of the Study:

• To demonstrate the efficacy of full-image micro-PIV for studying acoustic phenomena in microfluidics.
• To investigate the motion of microparticles under MHz-range acoustic actuation.
• To correlate experimental observations with theoretical models of acoustic waves.

Main Methods:

• Utilized full-image micro-PIV to capture transient particle motion.
• Employed piezo-actuation in the MHz range within microfluidic chambers.
• Analyzed the steady-state motion of 5 µm and 1 µm particles.

Main Results:

• Established micro-PIV as a powerful tool for acoustic studies in microfluidics.
• Observed particle motion consistent with acoustic eigenmodes (standing ultrasound waves).
• Validated experimental findings through numerical solutions of the acoustic wave equation.

Conclusions:

• Full-image micro-PIV analysis combined with transient motion imaging is highly effective for studying acoustic radiation forces and streaming.
• Particle dynamics in MHz-range acoustic fields are governed by acoustic eigenmodes.
• Experimental results align with theoretical acoustic wave models, validating the approach.