Growing world demand for gold and decreasing discovery rates of ore deposits necessitates new tech-niques for gold exploration. Current techniques for the detection of ppb level of gold, such as inductivelycoupled plasma mass spectrometry (ICP-MS) are not field-deployable. By contrast, current portable devicesuch as X-ray fluorescence (XRF) based sensors are not sufficiently sensitive. Thus, there is growing inter-est in developing a new, easy-to-use and fast method for detection of low concentrations of gold at thesite of an exploration drilling rig.Two optical methods, absorption and fluorescence, are examined for their suitability for low goldconcentration detection. Absorption study is based on the analysis of localised surface plasmon resonancepeak. For fluorescence analysis, the ability of gold nanoparticles to specifically catalyse the conversionof the non-fluorescent compound (I-BODIPY) to the fluorescent derivative (H-BODIPY) is used. For bothabsorption and fluorescence methods, the limit of quantification (LOQ) of gold nanoparticles (NPs) wasfound to be dependent on the NP size (71 ppb of 5 nm and 24.5 ppb of 50 nm NPs for absorption and 74 ppbof 5 nm and 1200 ppb of 50 nm NPs for fluorescence). The LOQ for fluorescence for 50 nm NPs measuredin a suspended core optical fibre was almost twice lower than in a cuvette. The field deployment potentialof these methods was also determined using a portable set up.Agnieszka Zuber, Malcolm Purdey, Erik Schartner, Caroline Forbes, Benjamin van der Hoek, David Giles, Andrew Abell, Tanya Monro, Heike Ebendorff-Heideprie

This work reports on the development of an optical fiber based probe for in vivo measurements of brain temperature. By utilizing a thin layer of rare-earth doped tellurite glass on the tip of a conventional silica optical fiber a robust probe, suitable for long-term in vivo measurements of temperature can be fabricated. This probe can be interrogated using a portable optical measurement setup, allowing for measurements to be performed outside of standard optical laboratories.

The detection of quantum-dot labeled proteins is demonstrated within lead silicate soft glass microstructured optical fibers using near infrared light. The protein concentration is measured using a new fluorescence capture approach. Light guided within the fiber is used both to excite and collect fluorescent photons, and the detection limit achieved without optimization of the fiber geometry is 1 nM, using just 3% of the guided mode of the fiber. Issues that currently restrict the detection of lower protein concentrations are discussed.