Development of a microresonator based photoacoustic imaging system

1) Brief description of the context of the research including potential impact

A new photoacoustic imaging system will be designed and optimised by first developing a new interrogation method and a new fabrication method to enhance the sensitivity of present polymer microresonator ultrasound sensors. The potential impact includes but not limited to, achieving state-of-art polymer sensor sensitivity, enabling deeper imaging depth, etc.

2) Aims and objectives

The overall aim will be to develop and apply microresonator sensors for practical photoacoustic tissue imaging. This will encompass several topics including the development of novel interrogation schemes, fabrication methods and undertaking photoacoustic imaging experiments.

3) Novelty of the research methodology

Polymer microresonator ultrasound sensors can provide extremely high acoustic sensitivity on account of the high degree of optical confinement they provide which yields very high Q-factors. However, this also makes them susceptible to thermal effects due to absorption of the interrogation laser light within the cavity. For example, it can produce distortion of the interferometer transfer function (ITF) which reduces the accuracy with which the optimum bias wavelength can be found resulting in reduced sensitivity. In this research, a new approach to mitigating this will be developed to reduce the total absorbed energy and minimise heating. As well as enabling a more accurate identification of the bias wavelength via careful control of the interrogation laser duty cycle, this may also allow higher interrogation laser powers to be used thus increasing acoustic detection sensitivity.

As well as considering the sensor interrogation, new sensor fabrication methods may be explored, for example the use of low modulus elastomers that provide higher acoustic sensitivity or ultra-high finesse glass cavities that yield higher Q-factors. Following identification of the optimal interrogation scheme and sensor fabrication method, a laboratory photoacoustic imaging system that will permit a single sensor to be scanned over various detection geometries (planar, cylindrical and spherical) will be developed in order to assess imaging performance relative to conventional piezoelectric receivers. This system will be used to identify the optimal detector characteristics, number of sensors, scan parameters. These will be used to inform the design of a practical multi-element imaging system that will be constructed and tested on tissue mimicking phantoms, ex vivo tissue and in vivo.

4) Alignment to EPSRC's strategies and research areas

This project is in alignment with ERSRC research and innovation priorities in the delivery plan 2019. The new sensor based on photoacoustic imaging, a novel hybrid imaging modality, will be highly beneficial to a wide variety of applications in clinical medicine, preclinical research, and basic biology for studying cancer, cardiovascular disease, abnormalities of the microcirculation and other conditions. What will be achieved in this project is not only about delivering a better quality of life by achieving a state-of-the-art sensor with superior sensitivity performance but also about ensuring higher standards of affordable healthcare by reducing cost significantly by substituting continuous wavelength laser with much more affordable pulse laser in the interrogation system.

5) Any companies or collaborators involved

None

The critical mass of scientists and engineers that i4health will produce will ensure the UK's continued standing as a world-leader in medical imaging and healthcare technology research. In addition to continued academic excellence, they will further support a future culture of industry and entrepreneurship in healthcare technologies driven by highly trained engineers with deep understanding of the key factors involved in delivering effective translatable and marketable technology. They will achieve this through high quality engineering and imaging science, a broad view of other relevant technological areas, the ability to pinpoint clinical gaps and needs, consideration of clinical user requirements, and patient considerations. Our graduates will provide the drive, determination and enthusiasm to build future UK industry in this vital area via start-ups and spin-outs adding to the burgeoning community of healthcare-related SMEs in London and the rest of the UK. The training in entrepreneurship, coupled with the vibrant environment we are developing for this topic via unique linkage of Engineering and Medicine at UCL, is specifically designed to foster such outcomes. These same innovative leaders will bolster the UK's presence in medical multinationals - pharmaceutical companies, scanner manufacturers, etc. - and ensure the UK's competitiveness as a location for future R&D and medical engineering. They will also provide an invaluable source of expertise for the future NHS and other healthcare-delivery services enabling rapid translation and uptake of the latest imaging and healthcare technologies at the clinical front line. The ultimate impact will be on people and patients, both in the UK and internationally, who will benefit from the increased knowledge of health and disease, as well as better treatment and healthcare management provided by the future technologies our trainees will produce.

In addition to impact in healthcare research, development, and capability, the CDT will have major impact on the students we will attract and train. We will provide our talented cohorts of students with the skills required to lead academic research in this area, to lead industrial development and to make a significant impact as advocates of the science and engineering of their discipline. The i4health CDT's combination of the highest academic standards of research with excellent in-depth training in core skills will mean that our cohorts of students will be in great demand placing them in a powerful position to sculpt their own careers, have major impact within our discipline, while influencing the international mindset and direction. Strong evidence demonstrates this in our existing cohorts of students through high levels of conference podium talks in the most prestigious venues in our field, conference prizes, high impact publications in both engineering, clinical, and general science journals, as well as post-PhD fellowships and career progression. The content and training innovations we propose in i4health will ensure this continues and expands over the next decade.