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Lab on Fiber Optrodes for Chemical and Biological Sensing: Recent Trends and Advances

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Chemical Sensors".

Deadline for manuscript submissions: closed (1 March 2018) | Viewed by 37584

Special Issue Editors


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Guest Editor
Optoelectronics Group, Department of Engineering, University of Sannio, I-82100 Benevento, Italy
Interests: nanobiophotonics; fiber optic nanoprobes; optical biosensors; plasmonics; lab-on-fiber technology; lab-in-a-needle
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Engineering, University of Sannio, I-82100 Benevento, Italy
Interests: lab-on-fiber technology; optical fiber sensors; optical biosensors; medical devices; metamaterials; plasmonics; smart materials
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Optoelectronics Group, Department of Engineering, University of Sannio, I-82100 Benevento, Italy
Interests: nanophotonics; fiber optic sensors; lab-on-fiber devices; chemical and biological sensing
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Lab-on-Fiber (LOF) technology is a new and fascinating field of research aimed at developing novel classes of optical fiber probes with unprecedented features in terms of miniaturization levels, functionalities, and overall performances, especially exploitable in chemical and biological sensing.

The key idea of LOF technology is to transform a ‘simple’ optical fiber into a multifunctional sensor, by means of the integration of functionalized materials and components (i.e. the labs) defined at the micro and nano scales.

In LOF-based sensors, the interaction between light and the parameters to be measured may take place either within the fiber itself, or around its lateral surface, including the tip. As a consequence, LOF technology embraces different devices that may be classified depending on the specific location where functional materials are integrated.

Specifically, LOF technology platforms can be subdivided in three main classes:

Lab around fiber devices, where functional materials are integrated onto the (outer) cylindrical surface of optical fibers;
Lab on tip devices, where the intrinsic light coupled termination of optical fibers plays the role of substrate for materials integration;
Lab in fiber devices, where the holey structure of micro-structured optical fibers (MOFs) is judiciously used for fluidic purposes and for hosting functional materials.

This Special Issue is proposed to collect invited manuscripts written by the leading authorities in the field. Specifically, with special focus on chemical and biological sensing applications, this Issue will include both research and review papers dealing with:

- successful development of novel LOF prototypes;
- integration of LOF devices with microfluidic and lab-on-chip systems;
- novel demonstrations of fabrication routes providing fine control on the materials integration at nanoscale;
- emerging self-organization methodologies for integrating and patterning functional materials.

Prof. Dr. Andrea Cusano
Prof. Dr. Armando Ricciardi
Prof. Dr. Marco Consales
Prof. Dr. Marco Pisco
Guest Editors

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Keywords

  • Lab on Fiber
  • Optical Fiber Sensors
  • Nanotechnology
  • Nanophotonics
  • Self assembly
  • Plasmonics
  • SERS
  • Metamaterials
  • Label free
  • Biosensing
  • Multimaterial Optical Fibers

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Published Papers (6 papers)

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Research

10 pages, 2754 KiB  
Article
Optical Fiber-Tip Sensors Based on In-Situ µ-Printed Polymer Suspended-Microbeams
by Mian Yao, Xia Ouyang, Jushuai Wu, A. Ping Zhang, Hwa-Yaw Tam and P. K. A. Wai
Sensors 2018, 18(6), 1825; https://doi.org/10.3390/s18061825 - 5 Jun 2018
Cited by 26 | Viewed by 6062
Abstract
Miniature optical fiber-tip sensors based on directly µ-printed polymer suspended-microbeams are presented. With an in-house optical 3D μ-printing technology, SU-8 suspended-microbeams are fabricated in situ to form Fabry–Pérot (FP) micro-interferometers on the end face of standard single-mode optical fiber. Optical reflection spectra of [...] Read more.
Miniature optical fiber-tip sensors based on directly µ-printed polymer suspended-microbeams are presented. With an in-house optical 3D μ-printing technology, SU-8 suspended-microbeams are fabricated in situ to form Fabry–Pérot (FP) micro-interferometers on the end face of standard single-mode optical fiber. Optical reflection spectra of the fabricated FP micro-interferometers are measured and fast Fourier transform is applied to analyze the cavity of micro-interferometers. The applications of the optical fiber-tip sensors for refractive index (RI) sensing and pressure sensing, which showed 917.3 nm/RIU to RI change and 4.29 nm/MPa to pressure change, respectively, are demonstrated in the experiments. The sensors and their optical µ-printing method unveil a new strategy to integrate complicated microcomponents on optical fibers toward ‘lab-on-fiber’ devices and applications. Full article
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14 pages, 28808 KiB  
Article
Optimization Strategies for Responsivity Control of Microgel Assisted Lab-On-Fiber Optrodes
by Martino Giaquinto, Alberto Micco, Anna Aliberti, Eugenia Bobeico, Vera La Ferrara, Menotti Ruvo, Armando Ricciardi and Andrea Cusano
Sensors 2018, 18(4), 1119; https://doi.org/10.3390/s18041119 - 6 Apr 2018
Cited by 22 | Viewed by 4378
Abstract
Integrating multi-responsive polymers such as microgels onto optical fiber tips, in a controlled fashion, enables unprecedented functionalities to Lab-on-fiber optrodes. The creation of a uniform microgel monolayer with a specific coverage factor is crucial for enhancing the probes responsivity to a pre-defined target [...] Read more.
Integrating multi-responsive polymers such as microgels onto optical fiber tips, in a controlled fashion, enables unprecedented functionalities to Lab-on-fiber optrodes. The creation of a uniform microgel monolayer with a specific coverage factor is crucial for enhancing the probes responsivity to a pre-defined target parameter. Here we report a reliable fabrication strategy, based on the dip coating technique, for the controlled realization of microgel monolayer onto unconventional substrates, such as the optical fiber tip. The latter was previously covered by a plasmonic nanostructure to make it sensitive to superficial environment changes. Microgels have been prepared using specific Poly(N-isopropylacrylamide)-based monomers that enable bulky size changes in response to both temperature and pH variations. The formation of the microgel monolayer is efficiently controlled through the selection of suitable operating pH, temperature and concentration of particle dispersions used during the dipping procedure. The effect of each parameter has been evaluated, and the validity of our procedure is confirmed by means of both morphological and optical characterizations. We demonstrate that when the coverage factor exceeds 90%, the probe responsivity to microgels swelling/collapsing is significantly improved. Our study opens new paradigms for the development of engineered microgels assisted Lab-on-Fiber probes for biochemical applications. Full article
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30 pages, 10500 KiB  
Article
Single Particle Differentiation through 2D Optical Fiber Trapping and Back-Scattered Signal Statistical Analysis: An Exploratory Approach
by Joana S. Paiva, Rita S. R. Ribeiro, João P. S. Cunha, Carla C. Rosa and Pedro A. S. Jorge
Sensors 2018, 18(3), 710; https://doi.org/10.3390/s18030710 - 27 Feb 2018
Cited by 20 | Viewed by 5328
Abstract
Recent trends on microbiology point out the urge to develop optical micro-tools with multifunctionalities such as simultaneous manipulation and sensing. Considering that miniaturization has been recognized as one of the most important paradigms of emerging sensing biotechnologies, optical fiber tools, including Optical Fiber [...] Read more.
Recent trends on microbiology point out the urge to develop optical micro-tools with multifunctionalities such as simultaneous manipulation and sensing. Considering that miniaturization has been recognized as one of the most important paradigms of emerging sensing biotechnologies, optical fiber tools, including Optical Fiber Tweezers (OFTs), are suitable candidates for developing multifunctional small sensors for Medicine and Biology. OFTs are flexible and versatile optotools based on fibers with one extremity patterned to form a micro-lens. These are able to focus laser beams and exert forces onto microparticles strong enough (piconewtons) to trap and manipulate them. In this paper, through an exploratory analysis of a 45 features set, including time and frequency-domain parameters of the back-scattered signal of particles trapped by a polymeric lens, we created a novel single feature able to differentiate synthetic particles (PMMA and Polystyrene) from living yeasts cells. This single statistical feature can be useful for the development of label-free hybrid optical fiber sensors with applications in infectious diseases detection or cells sorting. It can also contribute, by revealing the most significant information that can be extracted from the scattered signal, to the development of a simpler method for particles characterization (in terms of composition, heterogeneity degree) than existent technologies. Full article
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15 pages, 7039 KiB  
Article
Nanosphere Lithography on Fiber: Towards Engineered Lab-On-Fiber SERS Optrodes
by Giuseppe Quero, Gianluigi Zito, Stefano Managò, Francesco Galeotti, Marco Pisco, Anna Chiara De Luca and Andrea Cusano
Sensors 2018, 18(3), 680; https://doi.org/10.3390/s18030680 - 25 Feb 2018
Cited by 70 | Viewed by 7280
Abstract
In this paper we report on the engineering of repeatable surface enhanced Raman scattering (SERS) optical fiber sensor devices (optrodes), as realized through nanosphere lithography. The Lab-on-Fiber SERS optrode consists of polystyrene nanospheres in a close-packed arrays configuration covered by a thin film [...] Read more.
In this paper we report on the engineering of repeatable surface enhanced Raman scattering (SERS) optical fiber sensor devices (optrodes), as realized through nanosphere lithography. The Lab-on-Fiber SERS optrode consists of polystyrene nanospheres in a close-packed arrays configuration covered by a thin film of gold on the optical fiber tip. The SERS surfaces were fabricated by using a nanosphere lithography approach that is already demonstrated as able to produce highly repeatable patterns on the fiber tip. In order to engineer and optimize the SERS probes, we first evaluated and compared the SERS performances in terms of Enhancement Factor (EF) pertaining to different patterns with different nanosphere diameters and gold thicknesses. To this aim, the EF of SERS surfaces with a pitch of 500, 750 and 1000 nm, and gold films of 20, 30 and 40 nm have been retrieved, adopting the SERS signal of a monolayer of biphenyl-4-thiol (BPT) as a reliable benchmark. The analysis allowed us to identify of the most promising SERS platform: for the samples with nanospheres diameter of 500 nm and gold thickness of 30 nm, we measured values of EF of 4 × 105, which is comparable with state-of-the-art SERS EF achievable with highly performing colloidal gold nanoparticles. The reproducibility of the SERS enhancement was thoroughly evaluated. In particular, the SERS intensity revealed intra-sample (i.e., between different spatial regions of a selected substrate) and inter-sample (i.e., between regions of different substrates) repeatability, with a relative standard deviation lower than 9 and 15%, respectively. Finally, in order to determine the most suitable optical fiber probe, in terms of excitation/collection efficiency and Raman background, we selected several commercially available optical fibers and tested them with a BPT solution used as benchmark. A fiber probe with a pure silica core of 200 µm diameter and high numerical aperture (i.e., 0.5) was found to be the most promising fiber platform, providing the best trade-off between high excitation/collection efficiency and low background. This work, thus, poses the basis for realizing reproducible and engineered Lab-on-Fiber SERS optrodes for in-situ trace detection directed toward highly advanced in vivo sensing. Full article
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13 pages, 1160 KiB  
Article
Mn4+-Doped Magnesium Titanate—A Promising Phosphor for Self-Referenced Optical Temperature Sensing
by Francesca Venturini, Michael Baumgartner and Sergey M. Borisov
Sensors 2018, 18(2), 668; https://doi.org/10.3390/s18020668 - 24 Feb 2018
Cited by 18 | Viewed by 5931
Abstract
Phosphors based on magnesium titanate activated with Mn 4 + ions are of great interest because, when excited with blue light, they display a strong red-emitting luminescence. They are characterized by a luminescence decay which is strongly temperature dependent in the range from [...] Read more.
Phosphors based on magnesium titanate activated with Mn 4 + ions are of great interest because, when excited with blue light, they display a strong red-emitting luminescence. They are characterized by a luminescence decay which is strongly temperature dependent in the range from −50 C to 150 C, making these materials very promising for temperature sensing in the biochemical field. In this work, the optical and thermal properties of the luminescence of Mg 2 TiO 4 are investigated for different Mn 4 + doping concentrations. The potential of this material for temperature sensing is demonstrated by fabricating a fiber optic temperature microsensor and by comparing its performance against a standard resistance thermometer. The response of the fiber optic sensor is exceptionally fast, with a response time below 1 s in the liquid phase and below 1.1 s in the gas phase. Full article
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12 pages, 6665 KiB  
Article
UV Absorption Spectroscopy in Water-Filled Antiresonant Hollow Core Fibers for Pharmaceutical Detection
by Mona Nissen, Brenda Doherty, Jonas Hamperl, Jens Kobelke, Karina Weber, Thomas Henkel and Markus A. Schmidt
Sensors 2018, 18(2), 478; https://doi.org/10.3390/s18020478 - 6 Feb 2018
Cited by 58 | Viewed by 7418
Abstract
Due to a worldwide increased use of pharmaceuticals and, in particular, antibiotics, a growing number of these substance residues now contaminate natural water resources and drinking supplies. This triggers a considerable demand for low-cost, high-sensitivity methods for monitoring water quality. Since many biological [...] Read more.
Due to a worldwide increased use of pharmaceuticals and, in particular, antibiotics, a growing number of these substance residues now contaminate natural water resources and drinking supplies. This triggers a considerable demand for low-cost, high-sensitivity methods for monitoring water quality. Since many biological substances exhibit strong and characteristic absorption features at wavelengths shorter than 300 nm, UV spectroscopy presents a suitable approach for the quantitative identification of such water-contaminating species. However, current UV spectroscopic devices often show limited light-matter interaction lengths, demand sophisticated and bulky experimental infrastructure which is not compatible with microfluidics, and leave large fractions of the sample analyte unused. Here, we introduce the concept of UV spectroscopy in liquid-filled anti-resonant hollow core fibers, with large core diameters and lengths of approximately 1 m, as a means to overcome such limitations. This extended light-matter interaction length principally improves the concentration detection limit by two orders of magnitude while using almost the entire sample volume—that is three orders of magnitude smaller compared to cuvette based approaches. By integrating the fibers into an optofluidic chip environment and operating within the lowest experimentally feasible transmission band, concentrations of the application-relevant pharmaceutical substances, sulfamethoxazole (SMX) and sodium salicylate (SS), were detectable down to 0.1 µM (26 ppb) and 0.4 µM (64 ppb), respectively, with the potential to reach significantly lower detection limits for further device integration. Full article
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