High fidelity fibre-based physiological sensing deep in tissue

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T.R. Choudhary, M. G. Tanner, A. Megia-Fernandez, K. Harrington, H. A. Wood, A. Marshall, P. Zhu, S. V. Chankeshwara, D. Choudhury, G. Monro, M. Ucuncu, F. Yu, R. R. Duncan, R. R. Thomson, K. Dhaliwal and M. Bradley
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Heriot-Watt University / University of Edinburgh / University of Bath

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We have created a miniaturised optical probe only a little larger than a human hair capable of measuring key indicators of health deep in the human lung.

The team from the University of Edinburgh, Heriot-Watt University, and the University of Bath have combined custom optical fibres and chemical probes with bespoke optical systems to create a sensing “optrode” that can be used in the lungs via a bronchoscope.

Collaborating as part of the EPSRC funded Proteus IRC, this work brings technologies from research labs one step closer to healthcare implementation.

Clinical need:

Tiny changes in the physiology of tissue in health and disease can have profound impacts on how cells, tissues and drugs function. Acidity (pH) and tissue oxygenation are widely recognised as two environmental parameters that are critical in the regulation of cellular physiology. These parameters have not really been investigated inside the human body as it has not previously been possible to perform these measurements. These new methods, if taken to clinic, will lead to novel insights in disease biology.

Fibre optrode:

The optical fibre is only ~0.2mm in diameter, yet capable of holding 19 sensors on individual cores of the fibre. Each core is independent, like the many separate wires in an electrical cable, so can measure a different parameter.

The fluorescent sensors are made on 0.01 mm glass spheres, which then sit firmly in concave craters etched in the end of the fibre – self locating with the light guiding fibre cores.

Sensors:

The technology uses fluorescence sensors, which emit changing brightness and colours of light in response to acidity and oxygenation.

The size of the sensor allows measurements to be taken in the alveolar sacs where gas exchange occurs, deep inside the lungs. The alveolar sacs are critical for health and beyond the reach of standard technologies. Currently the sensing optrode measures oxygen and pH – key indicators of lung tissue health. However, the system has been designed in such a way that it can expand to take on new sensors that would allow the measurement of other parameters in the same kind of optrode. The new sensors can be developed in the chemistry lab and easily combined with the fibre optic imaging system being developed by the Proteus team.

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A combination of fibres and sensors will allow clinicians to see further into the lungs