Advances in fibre-optic sensing in medicine and biology

This paper presents a review of medical and biological applications of optical fibres, which span a wide range from light-pipes and pressure or displacement sensors through to complex chemical sensors. Coherent fibre bundles are needed for endoscopic imaging whilst single fibres may be used in both near infrared tomography and optical coherence tomography. Delivery of light to tissues, for example to activate targeted chemo-therapeutic agents (PDT), is also achieved conveniently with fibres. Chemical sensing can simply be achieved by transporting light to and from a measurement site with a plain fibre light guide for spectrophotometric or fluorimetry analysis. A further family of fibre-optic chemical sensors has either surface attached molecular recognition sites or a reaction chamber for achieving specific molecular detection. These chemical sensors may be based on the principles of surface plasmon resonance, interferometry, spectrophotometry or fluorimetry. Biological recognition with enzymes or antigen–antibody binding are used to achieve high specificity. The range of potential target molecules has increased rapidly over recent years from simple gases and ions through to large molecules such as DNA.