Monolithically integrated surface plasmon resonance sensor based on focusing diffractive optic element for optofluidic platforms

The design and fabrication of a three-channel, miniaturized surface plasmon resonance (SPR) sensor based on microfabricated focusing diffractive optical element (FDOE) is presented. The sensor uses an angular interrogation scheme and the FDOE delivers 15° angular beam divergence. The testing of the system was performed using NaCl solutions of varying concentrations and the corresponding angular sensitivity and minimum detection limit were found to be respectively 126°/RIU and 7.8 × 10−5 RIU. The use of standard lithography techniques is intended to reduce the cost and complexity of existing commercial devices and to promote mass production and integration. For example, the increasing level of optical integration in this sensor is suitable for microfluidic lab-on-a-chip applications with parallel analysis of multiple biochemical compounds.