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Posted: Apr 23, 2012
Researchers replicate Doctor Who's famous sonic screwdriver (w/video)
(Nanowerk News) For fans of the hit series Doctor Who, the Sonic Screwdriver will be a familiar device. But now an international team of EU-funded researchers has taken equipment designed for magnetic resonance imaging (MRI)-guided focused ultrasound surgery and demonstrated a real Sonic Screwdriver, lifting and spinning a free-floating 10 cm-diameter rubber disk with an ultrasound beam.
The team used energy from an ultrasound array to form a beam that can both carry momentum to push away an object in its path and, by using a beam shaped like a helix or vortex, cause the object to rotate.
The research was supported by the NANOPORATION ('Drug delivery to cancer cells using MRI (magnetic resonance imaging) guided focused ultrasound') project, which was granted more than EUR 2 million by the Marie Curie Industry-Academia Partnerships and Pathways (IAPP) funding scheme, part of the 'People' Theme of the EU's Seventh Framework Programme (FP7).
NANOPORATION, which started in 2009 and will run until 2013, brings together researchers from Israel and the United Kingdom with the aim of developing new solutions to overcome the current challenges of cancer chemotherapy. The programme focuses on exchange of expertise in MRI-guided therapeutic ultrasound, drug nano-capsules, nano-scale sonication research, cell biology and preclinical oncology research for targeted delivery of existing chemotherapy drugs.
The findings are set to appear in a forthcoming study in the American Physical Society's journal, Physical Review Letters ("Mechanical evidence of the orbital angular momentum to energy ratio of vortex beams").
Dr Mike MacDonald, of the Institute for Medical Science and Technology (IMSAT) in the United Kingdom, comments: 'This experiment not only confirms a fundamental physics theory but also demonstrates a new level of control over ultrasound beams which can also be applied to non-invasive ultrasound surgery, targeted drug delivery and ultrasonic manipulation of cells.'
The theory the team were testing had not previously been proved in a single experiment; it is valid for both sound and light, and is used in fields like quantum communications and biophotonics. The theory states that the ratio of angular momentum to energy in a vortex beam is equal to the ratio of the number of intertwined helices to the frequency of the beam.
Dr Christine Demore from IMSAT comments: 'For the first time, our experimental results confirm directly the validity of this fundamental theory. Previously this ratio could only be assumed from theory as the angular momentum and power in a beam had only ever been measured independently.'
The ultrasound beam generated by the researchers resembles the 'double-helix' structure of DNA but with many more twisted strands, or helices. This vortex beam generates a rotating, angular component of momentum that can exert torque on an object. In the recent publication, they showed how they could generate vortex beams with many intertwined helices, using a 1 000-element ultrasound transducer array as an acoustic hologram. These beams are so powerful they can levitate and spin the 90 g-disk made of ultrasonic absorber in water.
Dr MacDonald says that as part of the NANOPORATION project, the consortium are 'already starting to push the boundaries of what ultrasound can do in terms of targeted drug delivery and targeted cellular surgery', a field that has 'great potential for developing new surgical techniques, among other applications.'
But one can't help but wonder what the Doctor would think of the sonic device. It's anyone's guess, but here's hoping he would be impressed.
As Dr MacDonald puts it: 'Like Dr Who's own device, our sonic screwdriver is capable of much more than just spinning things around.'