This review presents an overview of the “lab-on-fiber technology” vision and the main milestones set in the technological roadmap to achieve the ultimate objective of developing flexible, ...multifunctional plug and play fiber-optic platforms designed for specific applications. The main achievements, obtained with nanofabrication strategies for unconventional substrates, such as optical fibers, are discussed here. The perspectives and challenges that lie ahead are highlighted with a special focus on full spatial control at the nanoscale and high-throughput production scenarios. The rapid progress in the fabrication stage has opened new avenues toward the development of multifunctional plug and play platforms, discussed here with particular emphasis on new functionalities and unparalleled figures of merit, to demonstrate the potential of this powerful technology in many strategic application scenarios. The paper also analyses the benefits obtained from merging lab-on-fiber (LOF) technology objectives with the emerging field of optomechanics, especially at the microscale and the nanoscale. We illustrate the main advances at the fabrication level, describe the main achievements in terms of functionalities and performance, and highlight future directions and related milestones. All achievements reviewed and discussed clearly suggest that LOF technology is much more than a simple vision and could play a central role not only in scenarios related to diagnostics and monitoring but also in the Information and Communication Technology (ICT) field, where optical fibers have already yielded remarkable results.
The book is an exciting source of information for individuals interested in learning about and marketing sensors. The book focuses on scientific and commercial advances in Fiber Bragg Grating (FBG) ...sensor technology since its discovery over 30 years ago. Discussions on new FBG sensor manufacturing and processing methods are provided by leading experts in the field. Novel applications of FBG sensor technology in engineering, energy, chemical and biological sectors are also included along with a clear identification of commercial opportunities in the next decade.
This review presents an overview of “Lab on Fiber” technologies and devices with special focus on the design and development of advanced fiber optic nanoprobes for biological applications. Depending ...on the specific location where functional materials at micro and nanoscale are integrated, “Lab on Fiber Technology” is classified into three main paradigms: Lab on Tip (where functional materials are integrated onto the optical fiber tip), Lab around Fiber (where functional materials are integrated on the outer surface of optical fibers), and Lab in Fiber (where functional materials are integrated within the holey structure of specialty optical fibers).
This work reviews the strategies, the main achievements and related devices developed in the “Lab on Fiber” roadmap, discussing perspectives and challenges that lie ahead, with special focus on biological sensing applications.
The Lab on Fiber Technology arises from the judicious synergy of forefront Key Enabling Technologies such as Photonics and Nanotechnology. This work reviews the strategies, the main achievements and related devices developed in the “Lab on Fiber” roadmap, by classifying this paradigm according to the specific location where functional materials are integrated, in Lab on Tip, Lab around Fiber and Lab in Fiber.
The integration of microfluidics and photonic biosensors has allowed achievement of several laboratory functions in a single chip, leading to the development of photonic lab-on-a-chip technology. ...Although a lot of progress has been made to implement such sensors in small and easy-to-use systems, many applications such as point-of-care diagnostics and
in vivo
biosensing still require a sensor probe able to perform measurements at precise locations that are often hard to reach. The intrinsic property of optical fibers to conduct light to a remote location makes them an ideal platform to meet this demand. The motivation to combine the good performance of photonic biosensors on chips with the unique advantages of optical fibers has thus led to the development of the so-called lab-on-fiber technology. This emerging technology envisages the integration of functionalized materials on micro- and nano-scales (
i.e.
the labs) with optical fibers to realize miniaturized and advanced all-in-fiber probes, especially useful for (but not limited to) label-free chemical and biological applications. This review presents a broad overview of lab-on-fiber biosensors, with particular reference to lab-on-tip platforms, where the labs are integrated on the optical fiber facet. Light-matter interaction on the fiber tip is achieved through the integration of thin layers of nanoparticles or nanostructures supporting resonant modes, both plasmonic and photonic, highly sensitive to local modifications of the surrounding environment. According to the physical principle that is exploited, different configurations - such as localized plasmon resonance probes, surface enhanced Raman scattering probes and photonic probes - are classified, while various applications are presented in context throughout. For each device, the surface chemistry and the related functionalization protocols are reviewed. Moreover, the implementation strategies and fabrication processes, either based on bottom-up or top-down approaches, are discussed. In conclusion we highlight some of the further development opportunities, including lab-in-a-needle technology, which could have a direct and disruptive impact in localized cancer treatment applications.
The integration on the optical fiber tip of nanostructures supporting resonant modes highly sensitive to local modifications of the surrounding environment allows the development of lab-on-fiber based biosensors.
The growing maturity of nanofabrication has ushered massive sophisticated optical structures available on a photonic chip. The integration of subwavelength-structured metasurfaces and metamaterials ...on the canonical building block of optical waveguides is gradually reshaping the landscape of photonic integrated circuits, giving rise to numerous meta-waveguides with unprecedented strength in controlling guided electromagnetic waves. Here, we review recent advances in meta-structured waveguides that synergize various functional subwavelength photonic architectures with diverse waveguide platforms, such as dielectric or plasmonic waveguides and optical fibers. Foundational results and representative applications are comprehensively summarized. Brief physical models with explicit design tutorials, either physical intuition-based design methods or computer algorithms-based inverse designs, are cataloged as well. We highlight how meta-optics can infuse new degrees of freedom to waveguide-based devices and systems, by enhancing light-matter interaction strength to drastically boost device performance, or offering a versatile designer media for manipulating light in nanoscale to enable novel functionalities. We further discuss current challenges and outline emerging opportunities of this vibrant field for various applications in photonic integrated circuits, biomedical sensing, artificial intelligence and beyond.
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.
We demonstrate a sensing scheme for liquid analytes that integrates multiple optical fiber sensors in a near-infrared spectrometer. With a simple optofluidic method, a broadband radiation is encoded ...in a time-domain interferogram and distributed to different sensing units that interrogate the sample simultaneously; the spectral readout of each unit is extracted from its output signal by a Fourier transform routine. The proposed method allows performing a multiparametric analysis of liquid samples in a compact setup where the radiation source, measurement units, and spectral readout are all integrated in a robust telecom optical fiber. An experimental validation is provided by combining a plasmonic nanostructured fiber probe and a transmission cuvette in the setup and demonstrating the simultaneous measurement of the absorption spectrum and the refractive index of water-methanol solutions.
An innovative fiber-optic hydrophone (FOH) was developed and investigated via an experiment at sea; it is capable of operating at a very low frequency of the seismic spectrum and detecting small ...magnitude earthquakes. The FOH exploits an optical fiber coil wrapped around a sensitive mandrel in a Michelson interferometric configuration. The FOH operated for about seven days at a water depth of 40 m, in the Campi Flegrei volcanic area (Southern Italy), and a few meters from a well-calibrated PZT hydrophone used as a reference. Thirty-three local earthquakes occurred during the simultaneous operation of the two hydrophones, allowing a straightforward comparison of the recordings. The local earthquakes occurred at an epicentral distance less than 2.5 km from the site of recording, and were estimated to be in the range of magnitude from -0.8 to 2.7. The analysis of the recorded earthquake waveforms in the frequency and time domains allowed retrieving the response function of the FOH in the frequency range from 5 to 70 Hz. The FOH responsivity in terms of acoustic pressure reached about 230 nm/Pa and was flat in the studied frequency range. Due to the high quality of the FOH recordings, this equipment is suitable for applications addressing submarine volcanic activity and the background seismicity of active faults in the ocean.
During implant surgery procedures, surgical precision is an essential prerequisite for the functional and aesthetic success of the prosthetic crown to be placed on the dental implant. A modern ...implant surgical approach should be standardized as much as possible to guarantee extreme precision in the insertion of the implant into the upper and lower bone jaws. Among the most common surgical errors during implant surgery there is the over-preparation of the surgical alveolus with possible damage to the contiguous anatomical structures. To avoid this problem, in the recent years, there has been an increasing attention to the development of new control techniques. In this paper, we describe an innovative ultrasound approach, which exploits the integration of an electro-acoustic transducer with the surgical drill used for realizing the alveolus in the bone that will host the implant. Specifically, he proposed approach is based on the "time-of-flight" detection technique for measuring the thickness of the residual bone subjected to the drilling. In order to demonstrate the feasibility of the proposed approach, here we report on a detailed numerical analysis aimed at studying the propagation of ultrasonic waves through the drill-bit and through the involved tissues. The obtained results confirm the validity of our approach, and enable for a future first prototype implementation of a hi-tech surgical drill-bit, which in general is suitable not only for dental implant surgery but also for other uses in oral surgery, maxillofacial surgery and for bone surgery.
Placing the needle inside the epidural space for locoregional anesthesia is a challenging procedure, which even today is left to the expertise of the operator. Recently, we have demonstrated that the ...use of optically sensorized needles significantly improves the effectiveness of this procedure. Here, we propose an optimized configuration, where the optical fiber strain sensor is directly integrated inside the epidural catheter. The new design allows the solving of the biocompatibility issues and increases the versatility of the former configuration. Through an in vivo study carried out on a porcine model, we confirm the reliability of our approach, which also opens the way to catheter monitoring during insertion inside biological spaces.
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