Optical fibre instrumentation for point of care diagnostics

Enhanced prediction and diagnosis in real time and at the point of care is recognised as a means of addressing national and global health challenges, with the development of sensors to detect and measure biomedical markers being a strategic priority. Chemical compounds excreted from the human body are believed to reflect certain metabolic conditions as well as the blood gas content. The changes in concentration of some compounds, referred to as biomarkers, and chemical composition in human samples such as breath, blood, urine, sweat and saliva can be linked to particular diseases and have been intensively used in medicine for early and minimally invasive diagnosis. There is considerable interest in the development of sensor devices to identify compounds both in vivo and ex vivo that can facilitate non-invasive diagnosis.

Sensing techniques based upon the use of optical fibre devices to probe the optical characteristics of nanomaterials that exhibit changes in their optical properties upon exposure to targeted chemical species are particularly attractive, in light of their potential high sensitivity, selectivity, the ready ability to multiplex arrays of sensors, and the prospect for remote sensing. Optical fibre grating devices, which are based upon a periodic perturbation of the refractive index of the core of the optical fibre, will be exploited as the sensing platform. Fibre gratings facilitate the controlled coupling of light between modes of the optical fibre structure at specific resonant wavelengths, with the wavelength showing sensitivity to perturbation of the fibre. Such devices have been applied extensively as sensors.

The techniques that will be exploited here further develop the methods pioneered at Cranfield that was awarded First Prize in the Frontier Science and Technology category of the 2004 National Measurement Awards, and further developed in a collaboration between Cranfield and Kitakyushu Universities, involving the deposition of nanoscale, functional coatings onto the surface of optical fibre devices.

The project brings together a multidisciplinary team with expertise in photonics, chemistry, analytical science and health care delivery. This will exploit cutting edge sensing techniques and materials to facilitate the design, fabrication and characterisation of the sensors, with the aim of developing a diagnostic instrument for use by a non-specialist in a clinical setting. The output and impact of the research will be maximised through functional testing of the instrumentation in a clinical environment.

Thus this proposal will develop a point-of-care (POC) device that will be assessed for accuracy, sensitivity, reproducibility, reliability and ease of use in a clinical setting. This will be achieved by (i) taking a fibre optic ammonia sensor previously demonstrated by the Cranfield and Kitakyushu teams, optimising its sensitivity and improving its immunity to application- specific interference from temperature and humidity, (ii) benchmarking its performance against established technologies, (iii) developing it into a prototype point-of-care device for use by non-specialist clinical staff, (iv) demonstrating the generic nature of the sensor platform and instrument by using it to monitor other biomarkers (e.g. acetone) and (v) demonstrate a multiplexed sensor capable of monitoring simultaneously a number of analytes, in this case those identified in (iv).

Enhanced prediction and diagnosis of diseases in real time and at the point-of-care, the theme of this proposal, is recognised by the government funding agencies (e.g. TSB and EPSRC) as a means of addressing national and global health challenges, with the development of sensors to detect and measure biomedical markers being a strategic priority. It is recognised that the availability of low cost, robust, non-invasive technologies capable of providing early diagnosis will impact on the well-being of the population, which will have a positive impact on economic activity and productivity, and reduce healthcare service spending. The major beneficiaries of this research will be patients and Clinicians. The developed instrument would allow faster, non-invasive and reliable diagnostics of diseases.

The sensor elements themselves can be reused if appropriate. For certain analytes the response is reversible, while for others the sensors can be washed and the response restored (to the original analyte, or to a different analyte) by re-infusing AN appropriate functional material. This may offer a significant cost benefit and have impact for use in developing countries.