In this lecture, we discussed Fluorescence molecules and how they can be used for detection of other molecules. The molecules are considered to have high energy states, which helps them with their detection. The photons discussed in the lecture can be seen as individual particles of light and have wave properties. The photon flux is the rate of the photon hitting a given space. The photon power density is the photon flux by the energy of each photon, while irradiance is the photon rate within a defined wavelength range and collecting area. The intensity is the energy/time within a defined wavelength range and collecting area. Next, the process of absorption is also discussed where the molecule absorbs a photon of light and it becomes excited, it tells us how many photons in wavelength band are absorbed by a material. This absorbed energy can be translated into rotation, vibration, or electron excitation to be read. Fluorescence is the molecules absorbing photons of light and are excited to higher electric states and the energy can be release by the emission of a photon of light. Internal Conversion is also discussed as another to ground the state of electrons without radiation. The concept of stokes shift and its applications are also discussed in the lecture in regard to fluorescence. However, a weakness of fluorescence is that the dimolecules can become inactive by photobleaching and quenching. The fluorescence may become decomposed over time leading to a reduction of quantum yield. The way the fluorescence is used is by attaching the dye by a covalent bond to a protein so we can detect the protein.
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
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