Complex ultrasound signals created by light
Research published in Applied Physics Letters
CDT Student Michael Brown and colleagues from the Biomedical Ultrasound Group at UCL recently had a research paper published in Applied Phyics Letters.
Generating arbitrary ultrasound fields with tailored optoacoustic surface profiles
M. D. Brown, a) D. I. Nikitichev, B. E. Treeby, and B. T. Cox. Read the full publication on AIP
Interview with Physics World
An interview on the research was also published in Physics World, an excerpt from which can be found here:
“A new way of creating specially shaped pulses of ultrasound using light and a 3D printer has been unveiled by Michael Brown and colleagues at University College London. The pulses, which are creating using the photoacoustic effect in a 3D-printed material, could be tailored to perform a range of tasks including manipulating biological cells and delivering drugs to specific parts of the body.
To create surfaces that output specific ultrasound signals, the team developed an algorithm that calculates the 3D surface profile required to create a desired ultrasound signal. “Our algorithm allows for precise control of the intensity of sound at different locations and the time at which the sound arrives, making it quick and easy to design surfaces or ‘lenses’ for a desired application,” says Brown.
Using this set-up, Brown and colleagues were able to create and detect ultrasound waves shaped like a “7”. But as well as creating pulses with complicated shapes, the technique could also be used to create intense ultrasound pulses. “One useful feature of the photoacoustic effect is that the initial shape of the sound that’s generated is determined by where the light is absorbed,” explains Brown. “This can be used to create tightly focused intense points of sound just by depositing an optical absorber on a concave surface, which acts like a lens.”
One possible application of the ultrasound generator is to create acoustic tweezers that can manipulate living cells and other delicate objects without any physical contact. Another possible use, according to Brown, is the targeted delivery of drugs. This would involve encapsulating the drugs in tiny bubbles that burst only when exposed to an ultrasound signal at, say, the site of a tumour.”