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Tunable-angle wedge transducer for improved acoustophoretic control in a microfluidic chip
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0003-0064-0086
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
2013 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 10, 105002- p.Article in journal (Refereed) Published
Abstract [en]

We present a tunable-angle wedge ultrasound transducer for improved control of microparticle acoustophoresis in a microfluidic chip. The transducer is investigated by analyzing the pattern of aligned particles and induced acoustic energy density while varying the transducer geometry, transducer coupling angle, and transducer actuation method (single-frequency actuation or frequency-modulation actuation). The energy-density analysis is based on measuring the transmitted light intensity through a microfluidic channel filled with a suspension of 5 mu m diameter beads and the results with the tunable-angle transducer are compared with the results from actuation by a standard planar transducer in order to decouple the influence from change in coupling angle and change in transducer geometry. We find in this work that the transducer coupling angle is the more important parameter compared to the concomitant change in geometry and that the coupling angle may be used as an additional tuning parameter for improved acoustophoretic control with single-frequency actuation. Further, we find that frequency-modulation actuation is suitable for diminishing such tuning effects and that it is a robust method to produce uniform particle patterns with average acoustic energy densities comparable to those obtained using single-frequency actuation.

Place, publisher, year, edition, pages
2013. Vol. 23, no 10, 105002- p.
Keyword [en]
Acoustic Radiation Force, Small Particles, Cell, Manipulation, Resonators, Channels, Field
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-131713DOI: 10.1088/0960-1317/23/10/105002ISI: 000324672700003ScopusID: 2-s2.0-84884878282OAI: diva2:657130
Swedish Research Council, 2011-5230EU, FP7, Seventh Framework Programme

QC 20131018

Available from: 2013-10-18 Created: 2013-10-17 Last updated: 2015-05-19Bibliographically approved
In thesis
1. On-chip Ultrasonic Sample Preparation
Open this publication in new window or tab >>On-chip Ultrasonic Sample Preparation
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Acoustofluidics has become a well-established technology in the lab-on-a-chip scientific community. The technology involves primarily the manipulation of fluids and/or particles in microfluidic systems. It is used today for variety of applications such as handling, sorting, washing and separation of cells or micro-particles, and for mixing and pumping of fluids. When such manipulation functions are integrated in micro-devices, the technology has been used for clinical sample preparation as well as for studying various fundamental bio-related questions.

In this doctoral thesis, we have developed different acoustic methods and micro-devices with the aim to create a multi-functional sample preparation platform. We introduced a simple method for in-situ measurements of acoustic energy densities inside a microfluidic channel, from which acoustic pressure amplitudes can be extracted. The method has been used for determining the magnitude of acoustic radiation forces acting on suspended particles and cells inside an acoustofluidic system. For optimization of acoustophoresis (i.e. manipulation of particles into the nodes of standing waves), we have investigated different designs of ultrasonic transducers based on tunable-angle wedges and backing layers attached to glass-silicon microfluidic chips. Furthermore, we have investigated the implementation of frequency-modulated actuation methodology combined with broadbanded ultrasonic transducers, and the implementation of multiple ultrasonic manipulation functions localized to spatially separated zones in a complex microchannel network. We demonstrate two different bio-applications useful for multi-step and multi-functional sample preparation. First, we demonstrate a micro-device for size-based separation, isolation and up-concentration of cells, followed by microscopy-based dynamic monitoring of individual cell properties when introducing different reagents. This holds great promise for use in cellular and molecular diagnostics. Second, we demonstrate an acoustic method for micro-vortexing in µL-volume reaction chambers in disposable polymer chips. The method is used for fast mixing of fluids, for disaggregating and re-suspending magnetically trapped and clumped micro-beads, and for cell lysis followed by DNA extraction. Finally, we demonstrate a temperature-controlled device compatible with high-acoustic-pressure (1 MPa) ultrasonic manipulation of cells, and we demonstrate that cells can be exposed to standing-wave ultrasound at 1 MPa for one hour without compromising the cell viability.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. ix, 65 p.
TRITA-FYS, ISSN 0280-316X ; 15:21
Ultrasound, Sample preparation, Particle manipulation
National Category
Other Physics Topics
Research subject
Physics; Biological Physics
urn:nbn:se:kth:diva-166746 (URN)978-91-7595-529-2 (ISBN)
Public defence
2015-06-05, FD5 AlbaNova University centrum,, Roslagstullsbacken 21, KTH, Stockholm, 07:14 (English)

QC 20150519

Available from: 2015-05-19 Created: 2015-05-15 Last updated: 2015-06-04Bibliographically approved

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Iranmanesh, Ida SadatWiklund, Martin
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