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Biomedical photonics

Optical fibre gratings can be configured to sense strain, bending, pressure, temperature and refractive index, which allows their use in a wide range of medical applications:
  • We have used long period and Bragg grating bend sensors to construct a vest capable of  monitoring the recruitment of various muscle groups to the breathing process
  • Long period grating sensor can also be used to monitor the mechanical vibrations associated with cardiac activity
  • Multiplexed Bragg grating sensors can be used to monitor temperature profiles and we were the first group to demonstrate this in-vivo.
  • We were the first to demonstrate that fibre Bragg gratings can be used to detect the MHz frequency strains associated with medical ultrasound
  • We have shown that the combination of refractive index sensitivity with a smart fibre coating can permit label-free detection of specific biochemical species and DNA
  • Femtosecond laser micromachining and inscription technology developed in the group is being combined with grating based sensors to produce micro-fluidic lab-on-a-chip devices
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General features of optical fibre sensors

 Small diameter – 125 microns
suitable for minimally invasive surgery
 Multiple sensors possible on a single fibre
In some cases hundreds of sensors can be integrated into a single fibre – the sensors can have an effective separation of less than a millimetre
 Made of glass, an insulator
- immune to electromagnetic interference so can be used in a MRI environment
 Can be made sensitive to a range of  chemical and biochemical species
- fibres are given a coating producing an index change in response ot the target species


Applications


The Photonics Research Group has been developing a range of  medical and biochemical sensors:
Bend sensors based on long period gratings and Bragg gratings for respiratory and cardiac monitoring
Temperature profile monitor for use during thermal therapy of cancerous tissue – 10 sensors covering a length of 5cm (higher spatial resolution possible)
Oesophageal pressure monitoring, based on Bragg gratings embedded in a compliant tube
Detection of specific DNA sequences using long period grating refractive index sensors to which DNA is attached
Measurement of the concentration of specific proteins (thrombin) at the femto-molar level using aptamers bound to a plasmonic sensor


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