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Vascular Optics: Opportunities in Microvascular Imaging and Photoplethysmography



Staff, Students, Academics

Speaker: Dr John Allen, Northern Medical Physics & Clinical Engineering, Freeman Hospital, Newcastle Upon Tyne, UK

Research Centre: Research Centre for Biomedical Engineering

Title: Vascular Optics: Opportunities in Microvascular Imaging and Photoplethysmography


Microvascular Imaging. The Newcastle Microvascular Diagnostics Service (MDS) provides a comprehensive array of optical and thermal technologies for assessing micro-circulatory blood flow and function. The clinical test portfolio covers four main areas: connective tissue disease and Raynaud’s phenomenon, specialist limb studies (i.e. amputation level, muscle compartment perfusion and venous physiology), neurovascular assessment, and burn wound depth assessment. A brief overview of the history and development of the MDS, tests performed, R&D undertaken, clinical management, and future service directions will be summarized.

Photoplethysmography (PPG). PPG is a low-cost optical technique that can detect blood volume changes in the microvascular bed. The PPG comprises a pulsatile (‘AC’) physiological waveform attributed to cardiac synchronous changes in the blood volume with each heart-beat, and is superimposed on a slowly varying (‘DC’) baseline with various lower frequency components attributed to respiration, sympathetic nervous system activity and thermoregulation. PPG technology can provide valuable information about the cardiovascular system, and is used in a wide range of commercially available medical devices for measuring oxygen saturation, blood pressure and cardiac output, assessing autonomic function and detecting peripheral vascular diseases. This talk highlights the recent resurgence of interest in the technique, driven by the demand for low-cost portable / wearable devices for the primary care and community based clinical settings, low-cost / miniature semiconductor components, and the advancement of signal processing / pulse wave analysis techniques.


Dr John Allen is Lead Clinical Scientist / Senior Research Scientist for Microvascular Diagnostics in Northern Medical Physics and Clinical Engineering, at Newcastle’s Freeman Hospital. He is also an Honorary Clinical Senior Lecturer in the Institute of Cellular Medicine at Newcastle University.

Dr Allen has over 25 years’ experience in vascular optics and associated clinical measurement, research and device development - publishing and presenting widely in each of these areas. John is an Accredited Senior Imaging Scientist and Fellow of the Royal Photographic Society.

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When and where

2.00pm - 3.00pmMonday 4th September 2017

C313 Tait Building City, University of London Northampton Square London EC1V 0HB United Kingdom