Nanocomposites for Optical Fibres for Use in Photoacoustic Sensing

Work Presented at the MRS Autumn Conference in Boston


UCL CDT PhD student Richard Colchester recently travelled to the large Materials Research Society (MRS) autumn conference, a large interdisciplinary materials science conference, which attracts over 5000 people from around the world to present his research. He and his group, lead by Dr Adrien Desjardins (Medical Physics and Bioengineering) and Dr Ioannis Papakonstantinou (Electronic and Electrical Engineering) presented a method for creating a nanocomposite material that comprises gold nanoparticles (AuNP) in a polydimethylsiloxane (PDMS) host on the distal end of optical fibres.

The optical absorption of this material has a pronounced wavelength-dependence across the visible and NIR spectral regions. As such, it is well suited for pulse-echo ultrasound and photoacoustic sensing of biological tissues, using excitation light transmitted by the optical fibre. For pulse-echo ultrasound, excitation light at 532 nm is absorbed by the AuNPs and the ensuing rapid heat deposition generates ultrasound waves that propagate from the optical fibre tip into tissue. With photoacoustic sensing, light of higher wavelengths is substantially transmitted by the material so that it propagates into tissue where it can be absorbed by chromophores. A combined US/PA probe was created using a nanocomposite-coated optical fibre, which included a second optical fibre with a Fabry-Pérot cavity at its distal end for reception of ultrasound waves. Co-registered ultrasound and photoacoustic images were generated from optical phantoms and biological tissues.

Richard said: "The scale and variety of research presented gave me the unique opportunity to explore many novel concepts and scientific fields. It was both interesting on a personal level and useful on an academic level, having met potential collaborators and seeing concepts that can be applied to my work."