Fabrication, operation and flow visualization in surface-acoustic-wave-driven acoustic-counterflow microfluidics

Area of Science:

• Microfluidics
• Acoustic manipulation
• Device fabrication

Background:

• Surface acoustic waves (SAWs) offer a method for driving liquids in microfluidic devices.
• The acoustic counterflow phenomenon enables precise fluid control.
• Portable microfluidic systems require efficient and reliable fluid handling techniques.

Purpose of the Study:

• To present a detailed fabrication protocol for a multilayered SAW acoustic counterflow device.
• To demonstrate the characterization and operation of the fabricated device for fluid pumping.
• To visualize and analyze fluid flow dynamics within the microfluidic channels.

Main Methods:

• Fabrication of a lithium niobate (LN) substrate with patterned interdigital transducers (IDTs).
• Creation of a polydimethylsiloxane (PDMS) channel using an SU8 master mold.
• Bonding of the PDMS channel onto the patterned LN substrate.
• Characterization and operation of the device to pump fluids.
• Visualization of liquid flow using microscopy techniques.

Main Results:

• Successful fabrication of a multilayered SAW acoustic counterflow device.
• Demonstration of on-chip fluid pumping capabilities.
• Visualization of fluid flow, including laminar flow and complex dynamics like vortices and particle accumulation.

Conclusions:

• The presented protocol provides a viable method for fabricating SAW-based microfluidic devices.
• The device effectively pumps fluids and allows for the study of various flow regimes.
• This technology holds potential for portable and advanced microfluidic applications.