Sensitivity Analysis of Different Shapes of a Plastic Optical Fiber-Based Immunosensor for Escherichia coli: Simulation and Experimental Results

Abstract

Conventional pathogen detection methods require trained personnel, specialized laboratories and can take days to provide a result. Thus, portable biosensors with rapid detection response are vital for the current needs for in-loco quality assays. In this work the authors analyze the characteristics of an immunosensor based on the evanescent field in plastic optical fibers with macro curvature by comparing experimental with simulated results. The work studies different shapes of evanescent-wave based fiber optic sensors, adopting a computational modeling to evaluate the probes with the best sensitivity. The simulation showed that for a U-Shaped sensor, the best results can be achieved with a sensor of 980 µm diameter by 5.0 mm in curvature for refractive index sensing, whereas the meander-shaped sensor with 250 μm in diameter with radius of curvature of 1.5 mm, showed better sensitivity for either bacteria and refractive index (RI) sensing. Then, an immunosensor was developed, firstly to measure refractive index and after that, functionalized to detect Escherichia coli. Based on the results with the simulation, we conducted studies with a real sensor for RI measurements and for Escherichia coli detection aiming to establish the best diameter and curvature radius in order to obtain an optimized sensor. On comparing the experimental results with predictions made from the modelling, good agreements were obtained. The simulations performed allowed the evaluation of new geometric configurations of biosensors that can be easily constructed and that promise improved sensitivity.

Development of an Immunocapture-Based Polymeric Optical Fiber Sensor for Bacteria Detection

“…Subsequently, Wandermur et al (2014) [6] developed a U-Shape POF sensor in an electronic platform for the rapid detection of bacteria. Following these studies, Rodrigues et al (2017) [20] investigated the sensitivity of different forms of a U-Shape POF sensor and searched for better efficiency at low bacterial dilution, while Lopes et al (2018) [21] used a specific U-Shape sensor format for the detection of sulfatereducing bacteria, such as Desulfovibrio alaskensis. In this paper we reinforce the use of POFs for the detection of specific bacterial species and the open the door to quantifying them.…”

“…Therefore, we removed the 10-µm thick cladding by the following procedure: the curve of the sensor was placed inside the folding of an optical cleaning tissue, applied 50 µL of acetone and the fiber curve is gently hand-rubbed. After that, the sensor was rinsed in distilled water to neutralize the effect of corrosion [20].…”

Surface Plasmon Resonance and Bending Loss-Based U-Shaped Plastic Optical Fiber Biosensors

“…However, in comparing the results obtained in this work with those from our previous publications [ 15 , 19 ], the sensitivity of bare sensor for Setup 1 was slightly better than those from these mentioned works. Additionally, sensors with gold film in Setup 2 also presented a response for lower bacteria concentration (10 3 CFU/mL), whereas in [ 42 ] the detection limit was 10 8 CFU/mL and in [ 19 ] the detection limit was 10 4 CFU/mL.…”

Development of an Immunocapture-Based Polymeric Optical Fiber Sensor for Bacterial Detection in Water

“…Therefore, we removed the 10 μm thick cladding by the following procedure: the curve of the sensor was placed inside the folding of an optical cleaning tissue, applied 50 μL of acetone and the fiber curve is gently hand-rubbed. After that, the sensor was rinsed in distilled water to neutralize the effect of corrosion [ 20 ].…”

“…Subsequently, Wandermur et al (2014) [ 6 ] developed a U-Shaped POF sensor in an electronic platform for the rapid detection of bacteria. Following these studies, Rodrigues et al (2017) [ 20 ] investigated the sensitivity of different forms of a U-Shaped POF sensor and searched for a better efficiency at low bacterial numbers, while Lopes et al (2018) [ 21 ] used a specific U-Shape sensor format for the detection of the sulfate-reducing bacteria, Desulfovibrio alaskensis , which is found in crude oil and responsible for the production of hydrogen sulfite (H 2 S), which reacts with water and produces sulfuric acid (H 2 SO 4 ), souring the oil and corroding pipelines.…”