Optoelectronic Capillary Sensors in Microfluidic and Point-of-Care Instrumentation

This paper presents a review, based on the published literature and on the authors’ own research, of the current state of the art of fiber-optic capillary sensors and related instrumentation as well as their applications, with special emphasis on point-of-care chemical and biochemical sensors, systematizing the various types of sensors from the point of view of the principles of their construction and operation. Unlike classical fiber-optic sensors which rely on changes in light propagation inside the fiber as affected by outside conditions, optical capillary sensors rely on changes of light transmission in capillaries filled with the analyzed liquid, which opens the possibility of interesting new applications, while raising specific issues relating to the construction, materials and instrumentation of those sensors

Advances in Optofluidics

Optofluidics a niche research field that integrates optics with microfluidics. It started with elegant demonstrations of the passive interaction of light and liquid media such as liquid waveguides and liquid tunable lenses. Recently, the optofluidics continues the advance in liquid-based optical devices/systems. In addition, it has expanded rapidly into many other fields that involve lightwave (or photon) and liquid media. This Special Issue invites review articles (only review articles) that update the latest progress of the optofluidics in various aspects, such as new functional devices, new integrated systems, new fabrication techniques, new applications, etc. It covers, but is not limited to, topics such as micro-optics in liquid media, optofluidic sensors, integrated micro-optical systems, displays, optofluidics-on-fibers, optofluidic manipulation, energy and environmental applciations, and so on

Novel Specialty Optical Fibers and Applications

Novel Specialty Optical Fibers and Applications focuses on the latest developments in specialty fiber technology and its applications. The aim of this reprint is to provide an overview of specialty optical fibers in terms of their technological developments and applications. Contributions include:1. Specialty fibers composed of special materials for new functionalities and applications in new spectral windows.2. Hollow-core fiber-based applications.3. Functionalized fibers.4. Structurally engineered fibers.5. Specialty fibers for distributed fiber sensors.6. Specialty fibers for communications

Fiber-enhanced Raman spectroscopy in aqueous media

This dissertation focuses on the investigation and development of an optical biosensor based on fiber-enhanced Raman spectroscopy (FERS) that provides chemical selective and sensitive label-free detection of biomolecules. FERS has been achieved by using various types of liquid core optical fibers, which guide the light within the liquid sample and increase the interaction length with the analyte molecules. The first part of this dissertation explains the FERS technique in detail and describes the current state of research of FERS. Several essential characteristics, such as fiber length, attenuation, material and refractive index, are thoroughly discussed in considerations of Raman intensity enhancement. Liquid-core fibers formed with hollow-core photonic-crystal fibers (HC-PCFs) and polymer fibers are introduced and discussed, as they are the most important breakthroughs. The objective of this research is to develop a robust optical fiber platform based on Raman spectroscopy that shows potential for use in bio-analytical and clinical applications. In this work, I demonstrate a combination of UV-resonance Raman spectroscopy (UV-RRS) and liquid-core fibers, to increases the sensitivity for the detection of low-concentrated pharmaceuticals tremendously. This combined enhancement technique was applied for the detection of bile pigments for monitoring of diseases related to hyperbilirubinemia and hyperbiliverdinemia. Their poor optical quality strongly limits the performances of the polymer-based liquid-core fibers. Therefore, the implementation of HC-PCFs was explored in two different types of optical guiding. Waveguiding in the visible range is achieved for the first time in both kinds of liquid-filled HC-PCFs, and therefore the Raman scattering wavelengths are not anymore limited to the insensitive NIR range. In order to achieve easy-to-use and stable FERS devices for further development, the performance of HC-PCFs in the aspect of light-confinement was studied with the help of a specially designed multi-channel Raman chemical imaging. The optimal fiber length, spatial filtering, and optical coupling were thoroughly analyzed, and an automatic coupling system was developed. With the development of optical fibers, FERS shows increasing potential as a robust, fast, chemical selective and sensitive tool for the detection of biomolecules in clinical, pharmaceutical, and biological applications.Diese Dissertation beschäftigt sich mit der Erforschung und Entwicklung eines optischen Biosensors, basierend auf faserverstärkter Raman Spektroskopie (engl. fiber-enhanced Raman spectroscopy, FERS). Dieser Sensor ermöglicht die chemisch selektive, sensitive und markierungsfreie Detektion von Biomolekülen. FERS wurde durch den Einsatz von verschiedenen optischen Fasern mit flüssigkeitsgefülltem Hohlkern bewerkstelligt. Die Fasern führen das Licht innerhalb der flüssigen Probe und vergrößern so die Strecke, auf der das Licht mit den Analytmolekülen wechselwirkt. Der erste Teil dieser Dissertation erklärt die FERS-Technik detailliert und beschreibt den derzeitigen Stand der Forschung bzgl. FERS. In den Überlegungen zur Verstärkung der Raman-Intensität werden mehrere wesentliche Eigenschaften wie Länge, Dämpfung sowie Material und Brechungsindex der Faser berücksichtigt und ausführlich behandelt. Flüssigkeitsgefüllte Fasern auf der Basis von photonischen Kristallfasern (HC-PCFs) und Polymerfasern mit Hohlkern werden eingeführt und besprochen, da sie den größten wissenschaftlichen Durchbruch darstellen. Das Ziel dieser Forschung ist es, ein stabiles Setup für faserverstärkte Raman-spektroskopische Messungen zu entwickeln, das Potential für den Einsatz in bioanalytischen und klinischen Anwendungen aufweist. In dieser Arbeit zeige ich eine Kombination von UV-Resonanz Raman Spektroskopie (UV-RRS) und flüssigkeitsgefüllten Fasern, um die Sensitivität der Detektion von niedrig konzentrierten Pharmazeutika immens zu verstärken. Diese kombinierte Verstärkungsmethode wurde ebenfalls angewandt, um Blutabbau-Pigmente zu detektieren. Dies kann für die Überwachung von Krankheiten genutzt werden, die mit Hyperbilirubinämie und Hyperbiliverdinämie in Verbindung stehen. Die schlechte optische Qualität von Polymerbasierten flüssigkeitsgefüllten Fasern schränkt deren Leistungsfähigkeit stark ein. Daher wurde der Einsatz von HC-PCFs für zwei verschiedene Lichtleitungsmechanismen untersucht. Erstmalig wurde Wellenleitung im sichtbaren Bereich in beiden flüssigkeitsgefüllten Fasertypen erzielt. Folglich ist die Wellenlänge der Raman-Streuung nicht mehr auf den unempfindlichen NIR-Bereich beschränkt. Um ein FERS-Gerät für die Weiterentwicklung zu realisieren, das leicht zu handhaben und stabil ist, wurden die HC-PCFs bezüglich ihrer Fähigkeit zum Lichteinschluss untersucht. Diese Untersuchung wurde mit Hilfe eines speziell konzipierten Aufbaus für die Raman-spektroskopische chemische Bildgebung durchgeführt. Optimale Faserlänge, Raumfilterung und optische Koppelung wurden sorgfältig ausgewertet und ein automatisches Kopplungssystem wurde entwickelt. Mit der Weiterentwicklung optischer Fasern zeigt FERS steigendes Potential als stabile, schnelle, chemisch selektive und sensitive Messmethode zur Detektion von Biomolekülen in klinischen, pharmazeutischen und biologischen Anwendungen

Laser Nano-Filament Explosion for Enabling Open-Grating Sensing in Optical Fibre

Embedding strong photonic stopbands into traditional optical fibre that can directly access and sense the outside environment is challenging, relying on tedious nanoprocessing steps that result in fragile thinned fibre. Ultrashort pulsed laser filaments have recently provided a non contact means of opening high aspect ratio nanoholes inside of bulk transparent glasses. This method has been extended here to optical fibre, resulting in high density arrays of laser filamented holes penetrating transversely through the silica cladding and guiding core to provide high refractive index contrast Bragg gratings in the telecommunication band. The point by point fabrication was combined with post-chemical etching to engineer strong photonic stopbands directly inside of the compact and flexible fibre. Fibre Bragg gratings with sharply resolved pi-shifts are presented for high resolution refractive index sensing from n = 1 to 1.67 as the nano-holes were readily wetted and filled with various solvents and oils through an intact fibre cladding.Comment: 21 pages, 12 figure

Nanomechanical optical fiber with embedded electrodes actuated by joule heating

Nanomechanical optical fibers with metal electrodes embedded in the jacket were fabricated by a multi-material co-draw technique. At the center of the fibers, two glass cores suspended by thin membranes and surrounded by air form a directional coupler that is highly temperature-dependent. We demonstrate optical switching between the two fiber cores by Joule heating of the electrodes with as little as 0.4 W electrical power, thereby demonstrating an electrically actuated all-fiber microelectromechanical system (MEMS). Simulations show that the main mechanism for optical switching is the transverse thermal expansion of the fiber structure

Microstructured optical waveguide-based endoscopic probe coated with silica submicron particles

Microstructured optical waveguides (MOW) are of great interest for chemical and biological sensing. Due to the high overlap between a guiding light mode and an analyte filling of one or several fiber capillaries, such systems are able to provide strong sensitivity with respect to variations in the refractive index and the thickness of filling materials. Here, we introduce a novel type of functionalized MOWs whose capillaries are coated by a layer-by-layer (LBL) approach, enabling the alternate deposition of silica particles (SiO2) at different diameters—300 nm, 420 nm, and 900 nm—and layers of poly(diallyldimethylammonium chloride) (PDDA). We demonstrate up to three covering bilayers consisting of 300-nm silica particles. Modifications in the MOW transmission spectrum induced by coating are measured and analyzed. The proposed technique of MOW functionalization allows one to reach novel sensing capabilities, including an increase in the effective sensing area and the provision of a convenient scaffold for the attachment of long molecules such as protein

Innovative Scintillating Optical Fibers For Detecting/Monitoring Gamma Radiation

A scintillating optical fiber sensor of this work consists of a scintillating optical fiber, connected to a photomultiplier tube (PMT) via a conventional silica optical fiber. When a gamma ray impinges on the scintillating optical fiber, photons are generated inside the fiber. The photons are trapped inside the fiber and guided through the PMT. The PMT output signal is acquired by a computer. Two types of scintillating optical fibers sensors were developed for gamma ray detection. The first one is a silica optical fiber doped with an inorganic scintillating agent. The second one is a liquid core waveguide optical fiber filled with a solution of a nanostructured core shell CdSe/ZnS quantum dot. Test results indicate that the scintillating optical fibers developed in this work are sensitive for detecting gamma radiation. These scintillating fibers offer more flexibility for applications in nuclear energy industry as well as in nuclear medical research