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

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.