Demonstration of low‐cost and compact SPR optical transducer through edge light coupling

Abstract

This work demonstrates experimentally a simple and practical low-cost surface plasmon resonance (SPR) system towards sensing applications. The cost is minimised through the elimination of many bulky optical components such as collimation lenses and prism. An off-shelf white light-emitting diode is directly coupled to a gold coated glass slide at a proper incident angle, while the output is collected with a bare multimode optical fibre mounted at the same incident angle and connected to a commercial spectrometer. Proper alignment of the components is achieved through building a mount using three-dimensional printing technology. The developed system is tested with glycerol solutions having different concentrations and the detection limit measured in the order of 10−4 RIU (refractive index unit). The system cost can be further reduced through mass production and when a low-cost in-house spectrometer is built while keeping the same precision.