Using Ultrasound to Tether Microorganisms

Tuesday 25 Oct 22


Anders Peter Andersen
DTU Aqua
+45 35 88 34 11


Mads Boje Rode
Laboratory Engineer
DTU Construct


Thomas Kiørboe
DTU Aqua
+45 35 88 34 01


Federica Miano
PhD student
DTU Aqua


Henrik Bruus
Professor, Section leader
DTU Physics
+45 45 25 33 07

Swimming microorganisms move as they please, and it requires patience to observe their appendage motions, swimming kinematics, and the resulting flows. In a new paper in the Journal of Experimental Biology, we show how to use ultrasound to acoustically tether and enable behavioral observations of individual microorganisms with simple laboratory equipment and a standard light microscope.

Acoustic tethering of microorganisms has been demonstrated in the applied physics literature with focus on confinement of many individuals, e.g., to explore properties of populations. However, the principle has not previously been described in the biology literature, and the technique has not been used to enable behavioural observations of individual microorganisms. We present a novel setup for acoustic tethering, and we demonstrate that it allows us to tether and observe individual dinoflagellates in focus in the mid-plane of the sample chamber without affecting their flagellar beat frequency. We argue that the technique will be applicable to explore appendage motion and swimming kinematics for a broad range of cell sizes and shapes, and we speculate that acoustic tethering may find wide application in biology for exploration of small aquatic organisms.

Read the paper here:

Rode M, Bioue A, Miano F, Bruus H, Kiørboe T, Andersen A (2022) Acoustic Tethering of Microorganisms, Journal of Experimental Biology 225, jeb244089, 7 pages.

Header image: Suspended microorganisms (circles, dark blue) swim freely in the absence of ultrasound (left), but by creating a standing ultrasound wave (solid lines, red), the organisms can be tethered in the mid-plane (dashed line, black) of the sample chamber (right).
16 APRIL 2024