Surface Plasmon Resonance Sensors - Term Paper Example

The metals used are mainly gold and silver. When the surface plasmons collide with light energy, a kind of resonance occurs named; surface Plasmon polarization. The resonance continues oscillating along the surface of the metal decaying gradually through loss of energy to the absorption into the metal and radiation to the media interface i.e. air or water or other surface (Bozhevolnyi, 2008). The resonance of the surface Plasmon is then used to monitor the reflected light energy from a prism coupler in relation to the angle of incidence.

This method can be applied to solve real life problems like observation of nanometer variations in density, thickness and molecular adsorption. Devices are being innovated every day in application of this technique. The surface Plasmon resonance sensors (SPRS) help detect chemicals, molecules, tissues like proteins, metals among other materials. This technology has been commercialized hence it is used in a very wide number of fields i.e. mass destruction weapons, medicine, security protocols, pharmacy, production plants, service delivery like water for residential use, optic communications and so on (Thirstrup, 2004).

New and Useful Applications of Surface Plasmon Resonance Sensors The applications could be classified into four distinct groups: 1. Optical sensors 2. Biosensors 3. Chemical sensor Optical Sensors The most influential application of this technology was in the fiber optic. In this type of sensors, data is converted into light energy and interfaced with a dielectric metal. The high refractive index of the metal allows for total internal refraction thus the light energy is infinitely refracted along the cable with minimum loss of energy.

This excites the surface Plasmons thus creating a surface resonance wave. The fiber optic cable is designed with a core metal in the centre, a bimetallic surround to the inner metal, a protective layer of metal preventing the effect of external waves to the wave in transit and insulators all around each layer. When a light is beamed on a prism at an angle greater than the critical angle of the media, total internal reflection occurs. The wave formed in the media could be manipulated through the use of a material with a higher di-electric constant.

This could be regulated to match the surface Plasmon resonance. It in turn creates a wave that travels along the surface of the metal at very high speeds. The energy formed through conversion of light energy to electronic energy can be controlled to achieve optimum sensor values i.e. increasing the two main parameters: sensitivity and signal-to-noise ratio. The sensor can be improved by using a dielectric media with a high refractive index. However, the materials used are limited to costs thus a balance needs to be maintained between the two (Wang, 2002).

Figure 1: prism experiment of the surface Plasmon wave Biosensors These are devices used to analyze the detection of analytes that combine physiochemical detector component with biological components e.g. tissues, molecules, fluids and so on. This technology takes advantage of the application of surface Plasmon resonance sensors at the molecular level. This is technically used to identify various types of molecules based on the level of excitement induced by a photon of light incident on the molecules of the object in test.

The biosensors are used to perform rather difficult tests i.e. testing the Ph of the brain, the Ph of the eye, the Ph under the skin and so on. The