A disposable, portable, miniature surface plasmon resonance sensor (30) having real-time referencing capability in the presence of any interaction, without changing the sensing surface condition is disclosed herein. The sensor (30) includes an electromagnetic radiation source (32) which generates a beam of electromagnetic radiation (52) that passes through a liquid crystal switch that includes a polarizer, plates and liquid crystal material sandwiched between the plates. The liquid crystal switch is disposed between the source (32) and an array of detectors (48). The liquid crystal switch has the ability to switch between a first and a second state of polarized radiation such that it provides the transverse magnetic component of the electromagnetic radiation for detection of SPR on a target element and, in the alternative, provides the transverse electric component of the electromagnetic radiation to determine a reference signal for the sensor (30). The polarized radiation is directed toward a layer (44) of a conductive material capable of sustaining surface plasmon resonance and reflected off layer (44) towards an array of electromagnetic radiation detectors (48) to make a determination of a property of the targeted element adjacent to layer (44) and produce an output signal in response to the received reflected electromagnetic radiation (52) indicative of the presence of, or representative of the concentration or a concentration range of, the targeted element.