Influence of the temperature on the opto-acoustophoretic effect

Area of Science:

• Acoustic manipulation
• Optical physics
• Fluid dynamics

Background:

• Opto-acoustophoretic mobility is observed in fluorescent and colored particles acoustically levitated in ultrasonic fields with specific optical illumination.
• This phenomenon requires both acoustic trapping and optical excitation.
• The precise physical origin of opto-acoustophoretic mobility remains under investigation.

Purpose of the Study:

• To investigate the physical origin of opto-acoustophoretic mobility.
• To compare numerical simulations with temperature-controlled experimental data.
• To understand the influence of temperature on the phenomenon.

Main Methods:

• Numerical simulations were performed to model the phenomenon.
• Temperature-controlled experiments were conducted.
• The study confronted simulation results with experimental observations.

Main Results:

• The numerical model successfully reproduced the properties of opto-acoustophoretic mobility.
• A thermofluidic instability was identified as the probable cause, suggesting a thermally induced fluid density gradient acts as a drag source.
• A surprising temperature threshold was observed, above which the phenomenon ceases regardless of energy input.

Conclusions:

• Thermofluidic instability is a likely origin for opto-acoustophoretic mobility.
• The observed temperature threshold challenges initial interpretations.
• The phenomenon may offer possibilities for contactless generation of customized flows using acoustically trapped particles.