Abstract
Many applications in the life-sciences demand non-contact manipulation tools for forceful but nevertheless delicate handling of various types of sample. Moreover, the system should support high-resolution optical imaging. Here we present a hybrid acoustic/optical manipulation system which utilizes a transparent transducer, making it compatible with high-NA imaging in a microfluidic environment. The powerful acoustic trapping within a layered resonator, which is suitable for highly parallel particle handling, is complemented by the flexibility and selectivity of holographic optical tweezers, with the specimens being under high quality optical monitoring at all times. The dual acoustic/optical nature of the system lends itself to optically measure the exact acoustic force map, by means of direct force measurements on an optically trapped particle. For applications with (ultra-)high demand on the precision of the force measurements, the position of the objective used for the high-NA imaging may have significant influence on the acoustic force map in the probe chamber. We have characterized this influence experimentally and the findings were confirmed by model simulations. We show that it is possible to design the chamber and to choose the operating point in such a way as to avoid perturbations due to the objective lens. Moreover, we found that measuring the electrical impedance of the transducer provides an easy indicator for the acoustic resonances.
Highlights
Requirements for scalable acoustic trappingFor applications employing acoustic forces the design and characterization of the setup is often a non-trivial task
Compatible with microfluidics, have been realized, which can be roughly divided into two groups:[5] in transverse resonators the acoustic wave travels in the transverse direction relative to the observation direction
In the following we present the experimental results we have obtained for the combination of acoustic trapping with holographic optical tweezers
Summary
For applications employing acoustic forces the design and characterization of the setup is often a non-trivial task. Particles are driven to the (pressure) nodes of a resonant standing wave, the shape of which depends on the geometrical design and material properties of the device. In a layered resonator, which typically consists of a planar fluid layer enclosed by glass layers, acting as reflectors, the acoustic wave travels normal to the observation plane. Each variant has its distinct value: transverse resonators typically employ more complex patterns and provide more possibilities to tailor the force landscape. They are more appropriate if one is interested in dextrous particle handling by acoustic forces alone.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
