A sensing system and method for biomolecular sensing. The system includes: a receptor for the at least one target, the receptor including a substrate and a transparent coating on the substrate having front and back surfaces; a light source positioned to direct at least a portion of light from the light source toward the coating on the receptor; and a detector positioned to capture the light reflected from the front and back surfaces of the coating, the detector identifying presence of at least one target based on a change in the interference pattern of captured light.