Characterisation of vacuum (physical vapour) deposited Lumogen optical films

Canberra, AC

Crystallinity in lumogen optical thin films

Canberra, AC

Grazing Incidence X-ray Studies of Ultra-Thin Lumogen Films

Lumogen® Yellow S0790 films have been produced on silicon wafer substrates via physical vapour deposition (PVD) and spin-coating (SC) methods. These coatings were characterised with X-ray reflectometry (XRR) and grazing incidence X-ray diffraction (GIXD) techniques. The results show that ultra-thin (less than 12nm) PVD films coat amorphously, with crystallinity becoming increasingly apparent with increasing film thickness. In contrast, measurements of ultra-thin (less than 2nm) spin-coated films reveal a second, apparently stable crystalline structure. © 2007, Elsevier Ltd

Characterisation of PVD Lumogen Films for Wavelength Conversion Applications

Bellingham, Washingto

Molecular photo-thermal optical coherence phase microscopy using gold nanorods

Optical coherence tomography (OCT) is a non-invasive interferometry imaging technique with micrometre scale resolution at millimetre scale penetration depths in highly scattering tissues. This study describes a new evolution of OCT, termed molecular optical coherence phase microscopy (molecular OCPM), which is capable of imaging the expression of molecular markers at the cellular level using gold nanorods as photothermal imaging agents. Gold nanorods were selected as the imaging agents due to their excellent photothermal energy conversion efficiency and tuneable plasmon bands. The gold nanorods were surface functionalized to achieve efficient and specific targeting of the tyrosine kinase human epidermal growth factor receptor HER2 molecular markers used as a model tumor biomarker. Phase modulation retrieval was used to generate photothermal maps which were overlayed on intensity images. Phase modulation within the filter corresponding to the laser excitation modulation frequency was clearly observed for cells targeted with the molecular photothermal imaging agents. These results confirm the ability of photothermal optical coherence phase microscopy to image accurately at the cellular level gold nanorods molecularly targeted to a biomarker expressed on cancer cell membranes, paving the way for its application to novel bioimaging procedures

Probing fluid flow using the force measurement capability of optical trapping

Interest in microfluidics is rapidly expanding and the use of microchips as miniature chemical reactors is increasingly common. Microfluidic channels are now complex and combine several functions on a single chip. Fluid flow details are important but relatively few experimental methods are available to probe the flow in confined geometry. We use optical trapping of a small dielectric particle to probe the fluid flow. A highly focused laser beam attracts particles suspended in a liquid to its focal point. A particle can be trapped and then repositioned. From the displacement of the trapped particle away from its equilibrium position one estimates the external force acting on the particle. The stiffness (spring constant) of the optical trap is low thus making it a sensitive force measuring device. Rather than using the optical trap to position and release a particle for independent velocimetry measurement, we map the fluid flow by measuring the hydrodynamic force acting on a trapped particle. The flow rate of a dilute aqueous electrolyte flowing through a plastic microchannel (W× H × L = 5 mm× 0.4 mm × 50 mm) was mapped using a small silica particle (1 µm diameter). The fluid velocity profile obtained experimentally is in very good agreement with the theoretical prediction. Our flow mapping approach is time efficient, reliable and can be used in low-opacity suspensions flowing in microchannels of various geometries