# Surface Plasmon Resonance-Based Fiber Optic Sensors Utilizing Molecular Imprinting
## 7 Summary and Outlook  
In summary, we have discussed fiber optic sensors based on surface plamon resonance (SPR) and localized surface plasmon resonance (LSPR) utilizing the molecular imprinting technique (MIT). Figure 16: **(a)** SEM micrograph of a MIP-based atrazine sensor showing polymer coated over fiber probe and **(b)** the calibration curve of the sensor for 10\({}^{-12}\)-10\({}^{-7}\) M of aqueous atrazine samples. Reprinted with permission from [47]. Copyright 2016 Elsevier. Figure 17: **(a)** SPR spectra and **(b)** variation in resonance wavelength with changing erythromycin concentration from 0–100 μm for SPR and molecularly imprinted nanoparticle-based ERY sensor. Reprinted with permission from [179]. Copyright 2016 The Optical Society (OSA). The fundamentals of SPR, LSPR and MIT and their implementation for the fabrication of optical fiber sensors have been presented. Further, an overview of the different molecular imprinted polymers, their synthesis methods and basic elements used for MIPs fabrication has been given. The sensors for biological and chemical analytes utilizing SPR/LSPR and MIT techniques and reported in the literature like TNT, vitamin B\({}_{2}\) and B\({}_{3}\), tetracycline, melamine, ascorbic acid, profenofos have been discussed along with the performance parameters. A summary of the performance parameters of these fiber optic sensors utilizing SPR/LSPR and MIP techniques is given in Table 3. The advantages of these sensors are that they can be used for the real time monitoring, label free sensing and cost-effectively. The use of the SPR technique improves the sensitivity and response time while the molecular imprinting makes the approach highly specific/selective for the analyte to be detected. Further, SPR/LSPR phenomenon using optical fiber configuration is more beneficial due to the additive advantage of immunity to external EM disturbance and ease of fabrication process for clinical applications. Implementation of optical fiber makes the sensing method capable of in vivo applications for biomedical diagnostics. The research on SPR/LSPR based fiber optic sensors using molecular imprinting technique has been initiated recently and only a few research papers have been published so far using this tailoring approach. Although, the sensors have various advantages as discussed above, a few parameters like sensitivity, selectivity and the detection limit need further improvement by using MIP nanostructures instead of thin films [179]. The fabrication of MIP polymers using suitable elements and the optimized amount of these is also a big challenge. However, the LSPR/SPR phenomenon can also be made more sensitive using the optimized/mono-dispersed size of metal nanoparticles and layers of metal/metal nanoparticles with not only uniform but also with optimized thicknesses of the layers. The main objective of this article is to show that this research area is wide open and lots of efforts are yet to be made to achieve highly sensitive and selective, quick, and low cost sensors suitable for in vivo applications, ability for real time detection, online monitoring and remote sensing. **Acknowledgments:** The present work is partially supported by CSIR (India). [PERSON] is grateful to UGC (India) for research fellowship.