Investigation of precise particle manipulation using zeroth- and first-order acoustic Bessel fields

Area of Science:

• Physics
• Biomedical Engineering
• Acoustics

Background:

• Acoustic tweezers offer non-contact particle manipulation for biomedical applications.
• Existing acoustic tweezer modes, like focal-point and vortex-trap, exhibit significant positioning errors.

Purpose of the Study:

• To investigate positioning errors in focal-point and vortex-trap acoustic fields.
• To develop and validate a closed-loop controller for enhanced acoustic manipulation precision.

Main Methods:

• Utilized an in-plane circular array acoustic tweezer device (2.3 MHz) to manipulate 90 μm polystyrene particles.
• Employed both focal-point (zeroth-order Bessel) and vortex-trap (first-order Bessel) fields.
• Implemented a closed-loop controller with optical feedback for particle localization and actuation adjustment.

Main Results:

• Without feedback, vortex-trap fields showed position errors of 0.266 mm, and focal-point fields exhibited unstable manipulation.
• With the closed-loop controller, vortex-trap errors decreased to <0.02 mm, and focal-point errors to <0.1 mm.
• Demonstrated significant improvement in manipulation accuracy for both modes.

Conclusions:

• The proposed closed-loop controller drastically improves the precision of acoustic particle manipulation.
• Established an experimentally validated method to overcome limitations of current acoustic tweezer operating modes.
• Highlights the potential for highly accurate acoustic manipulation in various scientific fields.