Surface plasma resonance SPRM is a popular optical method for the label-free detection of biomolecular interactions. It detects the variations in refractive index brought on by molecules adhering to a surface close by. SPR is based on this systems phenomenon, which happens when polarised light strikes a thin metal sheet at a specific angle and causes the metals surface electrons to resonate. A decrease in the intensity of the reflected light at a certain angle of incidence can be seen which is caused by this resonance. Surface plasma resonance SPRM is the incidence angle at which the dip appears.