Surface-Acoustic-Wave-Driven Acoustic Tweezing in a Silicon Microfluidic Chip

Area of Science:

• Biophysics
• Microfluidics
• Acoustic Manipulation

Background:

• Surface-acoustic-wave (SAW)-driven acoustic tweezers (ATs) are valuable for high-resolution ultrasonic sample manipulation.
• Hybrid ATs, combining reusable SAW chips with disposable microfluidic (MF) chips, offer cost-effectiveness and reduced contamination.
• Efficient acoustic coupling is crucial for maximizing acoustic pressure within MF channels.

Purpose of the Study:

• To investigate the frequency-dependent characteristics of acoustophoresis in 50-MHz hybrid ATs.
• To elucidate the role of bulk acoustic wave (BAW) resonances in silicon substrates for acoustic standing wave (SW) formation.
• To demonstrate the application of these hybrid ATs for soft matter and biological sample analysis.

Main Methods:

• Fabrication of hybrid acoustic tweezers using a SAW chip and a silicon microfluidic chip.
• Investigation of acoustophoresis at 50 MHz, analyzing frequency-dependent characteristics.
• Characterization of acoustic pressure generation within the microfluidic channel.

Main Results:

• Bulk acoustic wave (BAW) resonances in the silicon substrate were found to facilitate acoustic standing wave (SW) formation.
• Acoustic pressures up to 2.1 ± 0.5 MPa were generated within the microfluidic channel.
• The hybrid ATs successfully probed transient viscoelastic deformation of HEK293T cells and trapped Tetrahymena cells.

Conclusions:

• Hybrid ATs utilizing BAW resonances in silicon substrates are effective for generating high acoustic pressures.
• The developed platform enables acousto-mechanical testing of soft matter and biological samples.
• These findings support the potential of hybrid ATs for advanced cell analysis and manipulation.