Optical Detectors for Microsystems

Anti-Resonant Reflecting Optical Waveguides (ARROWs) are a novel form of optical waveguide technology, where light is confined and guided in the low index region of the sensor. This is achieved by the use of anti-resonant Fabry-Perot reflections. The ARROW sensor offers a 10 fold increase in sensitivity over traditional high index waveguides, which use evanescent sensing.The ARROW sensors are fabricated as slides, where a high index substrate (SF-10) is coated with both a low index silicon oxide (550 nm) and a high index silicon nitride (80 nm) layer.A single ARROW slide offers applications for vapour and Biosensing. However, by sandwiching two slides together such that the coatings are facing, the sensor may be used for applications where a capillary channel is required. These applications include Capillary Isoelectric Focussing (CIEF), Capillary Electrophoresis (CE), or Capillary Flow Cytometry (CFC), which are demonstrated here.For these latter applications, the capillary channel was formed using a novel method, where a photoresist sandwich layer was selectively exposed and developed to form the channel between the two slides.Results were recorded using either a linear CCD array (Vapour and Biosensing) or a 2D CCD Camera, with a Motion Picture Capture Card (CIEF, CE and CFC). Incident light was provided by either a tungsten halogen filament (Vapour and Biosensing) or a frequency doubled 10mW solid state laser operating at 473nm (CIEF, CE and CFC).