In this lecture, we continue the discussion of Fluorescence. Examples of results are shown from the fluorescent dyes and how they may be used from a fluorescent microscope. Getting results and images from Fluorescence Scanners are then discussed next. The laser is focused down on a point in the sensor and that point will give off light that can be detected. Then, we move on to the applications of homogeneous assays which are the same surface type the whole time (not half liquid and then half solid), but can only be performed for a small subset of assays. The fluorescence dyes can be placed on this or a heterogeneous assay which has one or both of the assay components immobilized on a sort of solid surface. The interaction occurs on the surface of the solid phase. The dyes are like antennas and when an electric field for a photon of light propagates, electrons are excited and the dye will light up. However, it depends on the direction of the propagation and polarization. With fluorescence polarization, the dye molecule will most strongly absorb light whose vector is parallel to the long axis of the molecule. The molecules have a preferred direction of physical orientation that may result in the polarized filter not becoming absorbed. If the dye molecule is attached to the protein, only the dye molecule oriented parallel to the Electric field of the incident light will be excited. It must also be stated that there is a time delay between the excitation and emission. When measuring polarization it is between 0 and 1, if we have high viscosity or volume, the molecule will rotate more slowly. Then, an example of a polarized fluorescence sensor is shown.
My research group is focused on the application of sub-wavelength optical phenomena and fabrication methods to the development of novel devices and instrumentation for the life sciences. The group is highly interdisciplinary, with expertise in the areas of microfabrication, nanotechnology, computer simulation, instrumentation, molecular biology, and cell biology. In particular, we are working on biosensors based upon photonic crystal concepts that can either be built from low-cost flexible plastic materials, or integrated with semiconductor-based active devices, such as light sources and photodetectors, for high performance integrated detection systems.
Using a combination of micrometer-scale and nanometer-scale fabrication tools, we are devising novel methods and materials for producing electro-optic devices with nanometer-scale features that can be scaled for low-cost manufacturing. Many of our techniques are geared for compatibility with flexible plastic materials, leading to applications such as low cost disposable sensors, wearable sensors, flexible electronics, and flexible displays. Because our structures manipulate light at a scale that is smaller than an optical wavelength, we rely on computer simulation tools such as Rigorous Coupled Wave Analysis (RCWA) and Finite Difference Time Doman (FDTD) to model, design, and understand optical phenomena within photonic crystals and related devices.
In addition to fabricating devices, our group is also focused on the design, prototyping, and testing of biosensor instrumentation for high sensitivity, portability, and resolution. Advanced instruments enable high resolution imaging of biochemical and cellular interactions with the ability to monitor images of biochemical interactions as a function of time. Using the sensors and instrumentation, we are exploring new applications for optical biosensor technology including protein microarrays, biosensor/mass spectrometry systems, and microfluidics-based assays using nanoliter quantities of reagents. The methods and systems developed in the laboratory are applied in the fields of life science research, drug discovery, diagnostic testing, and environmental monitoring. -From Professor Cunningham's Faculty Profile