CDT graduate Dr Richard Colchester wins best thesis prize

A CDT PhD graduate wins UCL Electronic and Electrical Engineering's Fabrizio Lombardi Prize for the Best Recent PhD Thesis presented at the 2017 Barlow Lecture at the Institute of Education.


Congratulations to Dr Richard Colchester, a recently graduated CDT PhD student who, on 21st July, was presented with the Fabrizio Lombardi prize for the best recent PhD thesis. His PhD was supervised by Dr Ioannis Papakonstantinou (UCL EEE) and Dr Adrien Desjardins (UCL Medical Physics) and was titled “Novel Optical Ultrasound Probes for Minimally Invasive Surgery”.

Judges believe that Richard's work represents a significant development in all-optical ultrasound imaging, moving it from a bench top system to a clinical device.

Here is the abstract of his thesis:

“Ultrasound has been used for diagnostic medicine since the mid 1950s. Since its inception the field has progressed and improved; with innovations including Doppler ultrasound for flow measurements and 3D ultrasound imaging. Recently, ultrasound probes for guidance and imaging during interventional surgery have been developed. However, traditional piezoelectric ultrasound is not well suited to high frequency, highly miniaturised applications.

Optically generated ultrasound is an emerging alternative, which is well suited for miniaturisation and enables the generation of high frequency, broadband ultrasound. Ultrasound is generated via the photoacoustic effect, in which incident light is absorbed, generating heat and a corresponding pressure rise which propagates as ultrasound.

This work is towards fabricating miniature all optical ultrasound devices that could be used in the context of minimally invasive procedures. With a view to this fibre optic ultrasound transmitters were fabricated, using a carbon nanotube and polydimethylsiloxane (PDMS) composite coating on the optical fibre tip. Coatings on a 300 μm core optic fibre exhibited high absorbance and generated ultrasound with peak-to-peak pressure up to 8.8 MPa measured at 1.5 mm away. Using these transmitters an all-optical ultrasound probe was fabricated using a Fabry-P´erot hydrophone for reception. As a proof of concept swine vascular tissue was imaged using 200 μm core diameter fibre optic ultrasound transmitters and demonstrated good correspondence with histology. In addition to this the device was extended to look sideways and integrated into a needle for imaging in vivo in a clinical context. Gold nanocomposite ultrasound transmitters were also fabricated in order to enable dual modality ultrasound and photoacoustic imaging.