The notion of surface plasmon resonance (SPR) sensor research emerged more than eight decades ago from the first observed phenomena in 1902 until the first introduced principles for gas sensing and biosensing in 1983. The sensing platform has been hand-in-hand with the plethora of sensing technology advancement including nanostructuring, optical technology, fluidic technology, and light source technology, which contribute to substantial progress in SPR sensor evolution. Nevertheless, the commercial products of SPR sensors in the market still require high-cost investment, component, and operation, leading to unaffordability for their implementation in a low-cost point of care (PoC) or laboratories. In this article, we present a comprehensive review of SPR sensor development including the state of the art from a perspective of light source technology trends. Based on our review, the trend of SPR sensor configurations, as well as its methodology and optical designs are strongly influenced by the development of light source technology as a critical component. These simultaneously offer new underlying principles of SPR sensor towards miniaturization, portability, and disposability features. The low-cost solid-state light source technology, such as laser diode, light-emitting diode (LED), organic light emitting diode (OLED) and smartphone display have been reported as proof of concept for the future of low-cost SPR sensor platforms. Finally, this review provides a comprehensive overview, particularly for SPR sensor designers, including emerging engineers or experts in this field.

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The impact of different gold nanoparticles (GNPs) structures on the plasmonic enhancement for DNA detection is investigated on a few-layer graphene (FLG) surface plasmon resonance (SPR) sensor. Two distinct structures of gold nanourchins (GNu) and gold nanorods (GNr) were used to bind the uniquely designed single-stranded probe DNA (ssDNA) of Mycobacterium tuberculosis complex (MTBC) DNA. The two types of GNPs-ssDNA mixture were adsorbed onto the FLGcoated SPR sensor through the π-π stacking force between the ssDNA and the graphene layer. In the presence of the complementary single-stranded DNA (cssDNA), the hybridization process took place and gradually removed the probes from the graphene surface. From SPR sensor preparation, the annealing process of the Au layer of the SPR sensor effectively enhanced the FLG coverage leading to a higher load of the probe DNA onto the sensing interface. The FLG was shown effective in providing a larger surface area for biomolecular capture due to its roughness. Carried out in the DNA hybridization study with SPR sensor, GNu, with its rough and spikey structures, significantly reinforced the overall DNA hybridization signal than the GNr with smooth superficies, especially in capturing the probe DNA. The DNA hybridization detection assisted by GNu reached the femtomolar range limit of detection (LoD). An optical simulation validated the extreme plasmonic field enhancement at the tip of the GNu spicules. The overall integrated approach of graphenebased SPR sensor and GNu-assisted DNA detection provided the proof-of-concept for the possibility for Tuberculosis disease screening using a low-cost and portable system potentially applied in a remote or the third world countries.