Methods for measuring a property of a sample material present at an interface of an emerging medium in a spectroscopic device include a sensor (10) featuring at least one dielectric member (14) disposed upon a entrant medium (12), with the dielectric member being of an optical thickness selected to produce an observable interference effect for an incident angle of light below the critical angle of total internal reflection at the interface with the dielectric member (14). The dielectric member (14) of the sensor device (10) may be modified and functionalized for binding of a sample analyte by disposing a sensing surface area (38, 40, 42) upon it. Moreover, an metal layer (18) may be added to an entrant medium (20) to produce a sensor (16) that generates observable optical phenomena both above (resonance) and below (interference) a given critical angle.