Optimal angular movement of laser beam in SPR using an embedded controller

Abstract

This paper proposes and implements the PIC microcontroller based Surface Plasmon resonance analysis of bio molecular interaction. Surface Plasmon resonance [SPR] has becoming an important optical bio-sensing technology in the areas of medical, biological , biochemistry, pollution detection, aircraft and laboratory research. The SPR works on the principle of TIR, that when the stepper motor mounted laser beam moving back and forth is focused on the hypotenuse of the gold coated BK-7 prism at an angle greater than the critical angle, hence the laser beam gets reflected back and SPR is generated outward side of the gold coated surface is measured using LDR. The generation of SPR is measured in terms of Refractive index, the refractive index changes with respect to the applied sample (Dielectric loading). Hence even for a small change in molecular interaction can be found using SPR. The laboratory prototype of PIC microcontroller based SPR was characterized in terms of reflectance and intensity with respect to the incident beam. In the design of instrument PIC 16F73 microcontroller is used to control the laser movement back and forth through stepper motor to increase the fastness and accuracy. This paper explains and demonstrates the importance of PIC microcontroller in the design and control of the instrument.