Volume 5- Issue 4: 2018 7872 ISSN: 2574-1241 DOI: 10.26717/BJSTR.2018.10.001967 Renata Zawisza. Biomed J Sci & Tech Res Research Article Biomedical Journal of Scientific & Technical Research (BJSTR) Open Access Introduction An optical fiber based sensor are very useful in many applications because of the compact size, electrical interference independence and suitability for remote sensing [1]. Recently, a significant effort has been devoted for the long period grating (LPG) - based sensors for medical application [2,3]. The real-time detection, high sensitivity and accuracy are desire properties for the medical sensors in terms of the facilitate prompt disease diagnosis [3]. In spite of the high sensitivity of the LPG, the main asset is possibilities of modifying the optical structure with thin functional coatings in terms of facilitating highly selective and fast measurement in real time with the reported resolution of refractive index (RI) change up to 10−6 [4]. To detect any molecular elements, the LPG surface needs to be functionalized by e. g. enzymes [5], gold nanoparticles [6], antibodies [7] or cross- linking bioreceptors [8]. The LPG is an optical periodic structure, where transmission spectrum consists of the resonance dips at discrete wavelength [9]. When it comes to achieve very sensitive structure, the LPG should work close to the turning point, where the dual-resonance appears. Such dual- resonance long period grating (DR-LPG) has been shown to be ultra-sensitive [10] regarding the micro-scale label- free detection [11]. The detailed theory of the DR-LPG structure can be found in [12,13]. To satisfy the need for very accuracy molecules detection and to maintain a stable temperature of the measurement, the DR-LPG can be combining with other optical elements [14]. Among various solution, the fiber loop mirror (FLM) provides several advantages, including high extinction ratio, and low cost of final arrangement. The part of high birefringence fiber (Hi-Bi fiber) from FLM structure ensures ambient temperature changes controlling by the interference dips shifting/amplitude intensity changing observation. Moreover due to filtering properties of the FLM, it provides possibilities of control of the wavelength spacing between interference dips, limitation of the temperature and strain cross- sensitivities and consequently enhancement of the sensitivity of the specific sample detection [15].In this paper, for the first time of our knowledge, we present the combined structure of the DR-LPG in the FLM for biotin-avidin reaction as a potential platform for medical application. In particular, the described optical platform can be applied as a sensor for limitless biomarkers or molecules, similarly to LPG which was already used to detect, e.g. bacteria [16]. It is possible due to the ultra-high sensitivity towards a refractive index of surrounding environment. Moreover, the introduction of a reception layer to Dual-Resonance Long Period Grating in Fiber Loop Mirror Based Platform for Cheap Biomedical Sample Detection with High Resolution Renata Zawisza* 1 , Leszek R Jaroszewicz 1 , Anna Celebańska 2 , Predrag Mikulic 2 and Wojtek J Bock 2 1 Institute of Applied Physics, Military University of Technology, Poland 2 Photonics Research Center, Université du Québec en Outaouais, Canada Received: : October 09, 2018; Published: : October 29, 2018 *Corresponding author: Renata Zawisza, Institute of Applied Physics, Military University of Technology, Poland Abstract A dual-resonance long period grating (DR-LPG) embedded in fiber loop mirror (FLM) was employed as a sample for the development of the biosensor application. The DR-LPG) acts as a sensing part for biological molecules detection, whereas FLM enhances the rapid signal monitoring, which oversees the wavelength filtering properties. Herein, the DR-LPG surface was functionalized with biotin in terms of the avidin binding reaction detection. The detection mechanism is based on the alteration the refractive index of the DR-LPG surrounding monitored by the tracking interference dips changing. Moreover, by applying a broadband diode and photodetector we ensured the low-cost of the system. Keywords: Dual- Resonance Long Period Grating (DR-LPG); Fiber Loop Mirror (FLM); Biotin- Avidin Reaction; Biosensing Platform. Abbreviations: DR-LPG: Dual- Resonance Long Period Grating; FLM: Fiber Loop Mirror; LPG: Long Period Grating; RI: Refractive Index; APTES: Amino Propyl Tri Ethoxy Silane; EDC: 1-Ethyl-3-(3-Dimethylaminopropyl)Carbodiimide; PBS: Phosphate Buffer Saline; LOF: Lab-On-a-Fiber