1. 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.