In this lecture, we finished our discussion over optical sensors. We started with discussing a photon moving between 2 mirrors with 100% efficiency, the photon gets to "sample" the media between the mirrors with no loss. This was able to be compared to an acoustic resonator and the wavelength that moves within it. However, the waves in the optical sensor represent an Electric Field that oscillates like a wave, but between positive and negative. In reality, though there is no 100% efficiency and the Electric Field would decay. Looking at an optical resonator biosensor, we are looking for a strong interaction with the media and a high Quality Factor with a good resolution for small wavelengths can be measured. Then, we took a look at 1D and 2D Surface Photonic Crystals and how they work and operate with the properties using the photon theory above. The structure is able to resonate one wavelength of light and have Quality Factor better than a Surface Plasmon Resonance 100x better. Important factors that determine the structure results include the surface and the refractive index. Also dielectric resonators are used rather than metal ones in order to minimize the loss. This maximizes the sensitivity. The last thing discussed was the fabrication of these sensors.
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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University of Illinois, Urbana-Champaign, IL