Realization of Compact Tractor Beams using Acoustic Delay-Lines

Asier Marzo, Abanoub Ghobrial, L Cox, Mihai Caleap, Anthony Croxford, Bruce Drinkwater

Research output: Contribution to journalArticle (Academic Journal)peer-review

52 Citations (Scopus)
494 Downloads (Pure)


A method for generating stable ultrasonic levitation of physical matter in air using single beams (also named tractor beams) is demonstrated. The method encodes the required phase modulation in passive unit cells into which the ultrasonic sources are mounted. These unit cells use waveguides such as straight and coiled tubes to act as delay-lines. It is shown that a static tractor beam can be generated using a single electrical driving signal and a tractor beam with one-dimensional movement along the propagation direction can be created with two signals. Acoustic tractor beams capable of holding millimeter-sized polymer particles of density 1.25 g/cm3 and fruit-flies (Drosophila) are demonstrated. Based on these design concepts we show that portable tractor beams can be constructed with simple components that are readily available and easily assembled enabling applications in industrial contactless manipulation and biophysics.
Original languageEnglish
Number of pages6
JournalApplied Physics Letters
Issue number1
Early online date1 Jan 2017
Publication statusPublished - 2 Jan 2017


  • phase modulation
  • signal generators

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