Integrated optical technologies for analytical sensing (original) (raw)
Related papers
Optical waveguide fabrication in silica using flame hydrolysis
1990
This thesis is concerned with the fabrication, assessment and application of doped silica waveguides using Flame Hydrolysis Deposition. Deposition apparatus has been designed and constructed. This equipment consists of a gas supply assembly, a bubbler cabinet, a deposition box and a chemical scrubber. An optimum sintering regime for the low density silica soot has been established consisting of 60 minutes at 1250 0 C. This regime is dependent on the levels of P20S. Ge02 andlor Ti02 doping in the silica host. Independent control of layer thickness and index is achieved. Refractive index can be varied by changing the doping levels, and thickness, by increasing the 1.1 PERSPECTIVE 1 1. 2 SYNOPS IS OF THES IS 1 CHAPTER 2 FABRICATION TECHNIQUES-DESCRIPTION AND APPRAISAL 2.1 DESCRIPTION OF FABRICATION TECHNIQUES 2.1.1 Chemical Vapour Deposition 2.1.2 Electron-Beam Vapour Deposition 2.1.3 RF Sputtering 2.1.4 Thermal Oxfdat ion 2.1.5 Sol-gel Processes 2.1.6 Thermal Nitridation 2.1. 7 Ion Imp Iant at ion 2.1.8 Flame Hydrolysis Deposition 2.2 MERITS AND DEMERITS 2.3 FLAME HYDROLYSIS DEPOSITION OF SILICA: APPARATUS DESIGN AND CONSTRUCTION 11 2.3.1 Gas Supply Assembly 12 2.3.2 Bubbler Cabinet 13 2.3.3 Depos it ion Chamber 16 2.3.4 Scrubber System 19
2003
Previous research into the use of Flame Hydrolysis Deposition (FHD) of glasses in integrated optics has focused on the successful commercial exploitation of low cost optical devices within the field of telecommunications and optoelectronics. Recently we have sought to apply these fabrication technologies to the development of optical biochips, utilising their ability to be integrated with microfluidics as a 'Lab-on-a-chip' platform. In this paper, we carry this development forward by seeking to create a microarray of integrated optical sensing elements, addressed using a glass-polymer hybrid technology in which poly(dimethylsiloxane), PDMS, is used as an elastomeric packaging over-layer. In particular, we describe the wide range of modelling and microfabrication processes required for the successful manufacture, integration and packaging of such arrays. The integration of both optical and fluidic circuits in this device avoids precise alignment requirements and results in a compact, robust and reliable device. Finally, in this paper, we describe the implementation of a pumping system for delivering small amounts of fluid across the array together with an optical signal treatment. #
Effect of conditions of silica film preparation on the spectral behaviour of a fluorescent probe
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1995
Using the sol-gel technique for the hydrolysis of tetraethoxysilane (TEOS), the synthesis of porous silicate films was carried out in the presence of additives comprising the non-ionic surfactant Triton X-100 (type I films), or the polymer poly(ethylene oxide) (PEO) (type II films) with molecules of the fluorophore pyrene (Py) and with Cu 2 ÷ ions as luminescence quenchers, incorporated at the gelation stage. The reaction between photoexcited molecules of Py and Cu 2÷ ions was used to characterize the adsorption and the structural features of the compounds formed. In both types of film, the fluorophore was firmly held in a silica gel matrix. A photoreaction involving electron transfer from Py to Cu 2 ÷ ions does not occur in type I films and the efficiency of Py fluorescence remains high irrespective of the quencher concentration. In type II films, the quenching of the Py fluorescence is effected by Cu 2+ ions. A conclusion was reached about the solubilization of Py inside micelles of Triton X-100 and encapsulation in a type I silica matrix during its maturation. Rate constants of quenching calculated according to the Stern-Volmer equation for variations of intensity and lifetimes of Py* in type II films indicate a mixed reaction mechanism involving electron phototransfer which includes dynamic and static components.
Microelectronic Engineering, 1999
The aim of this study was to develop and optimise a process to etch deep, high aspect ratio microstructures in glasses. To this end, we examined the use of flame hydrolysis deposition (FHD) to form integrated lab-ona-chip structures involving siliea-on-silicon. The PMD process allows buried optical waveguide structures to be produced, which are isolated from the surface using a glass overlayer, or cladding. This arrangement allows sensing regions, such as microanalytical chambers and capillary channels for microfluidics, to be defined by etching through the upper cladding. In this paper we also demonstrate a simple fluorescence assay measurement, to illustrate the potential application of this technology.
Use of three longer-wavelength fluorophores with the fiber-optic biosensor
Sensors and Actuators B: Chemical, 1995
With the availability of fluorescent dyes that are excited above 600 nm and couple easily to proteins, portable biosensors are becoming a reality. The use of diode lasers to excite these dyes permits systems to be made small and lightweight. An added benefit to switching to the near-infrared (NIR) regime is the reduction in background fluorescence from environmental and clinical samples. Previously, an evanescent wave biosensor was developed at the Naval Research Laboratory (NRL) using tetramethylrhodamine isothiocyanate as the fluorescent tag. Using this biosensor, toxins and other proteins have been detected down to 1 ng ml ~ and bacteria to 3000 cells ml ]. In this study, two new biosensors have been constructed using the same design with only selected components changed for detection of other fluorophores. An antigen (goat IgG) is labelled with one of three fluorophores: tetramethylrhodamine isothiocyanate, Cy5 and a near-infrared dye. The direct binding of each labelled antigen to an antibody-coated fiber-optic probe is measured. Comparisons of signal magnitudes, level of detection achieved, and photobleaching have been performed. ~ Plenary paper. 0925-4005/95/$09.50 © 1995 Elsevier Science S.A. All rights reserved SSD1 0925-4005(95)01659-J
Fresenius' Journal of Analytical Chemistry
Current concepts for chemical and biochemical sensing based on detection with optical waveguides are reviewed. The goals are to provide a framework for classifying such sensors and to assist a designer in selecting the most suitable detection techniques and waveguide arrangements. Sensor designs are categorized on the basis of the five parameters that completely describe a light wave: its amplitude, wavelength, phase, polarization state and timedependent waveform. In the fabrication of a successful sensor, the physical or chemical property of the determined species and the particular light wave parameter to detect it should be selected with care since they jointly dictate the sensitivity, stability, selectivity and accuracy of the eventual measurement. The principle of operation, the nature or the detected optical signal, instrumental requirements for practical applications, and associated problems are analyzed for each category of sensors. Two sorts of sensors are considered: those based on direct spectroscopic detection of the analyte, and those in which the analyte is determined indirectly through use of an analyte-sensitive reagent. Key areas of recent study, useful practical applications, and trends in future development of optical waveguide chemical and biochemical sensors are considered.
Process development for waveguide chemical sensors with integrated polymeric sensitive layers
2008
Due to the proper optical property and flexibility in the process development, an epoxy-based, high-aspect ratio photoresist SU-8 is now attracting attention in optical sensing applications. Manipulation of the surface properties of SU-8 waveguides is critical to attach functional films such as chemically-sensitive layers. We describe a new integration process to immobilize fluorescence molecules on SU-8 waveguide surface for application to intensity-based optical chemical sensors. We use two polymers for this application. Spin-on, hydrophobic, photopatternable silicone is a convenient material to contain fluorophore molecules and to pattern a photolithographically defined thin layer on the surface of SU-8. We use fumed silica powders as an additive to uniformly disperse the fluorophores in the silicone precursor. In general, additional processes are not critically required to promote the adhesion between the SU-8 and silicone. The other material is polyethylene glycol diacrylate (PEGDA). Recently we demonstrated a novel photografting method to modify the surface of SU-8 using a surface bound initiator to control its wettability. The activated surface is then coated with a monomer precursor solution. Polymerization follows when the sample is exposed to UV irradiation, resulting in a grafted PEGDA layer incorporating fluorophores within the hydrogel matrix. Since this method is based the UV-based photografting reaction, it is possible to grow off photolithographically defined hydrogel patterns on the waveguide structures. The resulting films will be viable integrated components in optical bioanalytical sensors. This is a promising technique for integrated chemical sensors both for planar type waveguide and vertical type waveguide chemical sensors.
Coaxial fiber-optic chemical-sensing excitation-emission matrix fluorometer
Optics Letters, 2011
Great reductions in the overall size and complexity of high throughput multichannel UV-visible fluorometers were achieved by coupling a compact optical fiber array to compact dispersive transmission optics. The coaxial configuration centers on the insertion of a silica/silica optical fiber into the hollow region of a UV-fused silica capillary waveguide. The outer core delivers the maximum power of the narrow wavelength region of the excitation spectrum created by coupling a xenon arc discharge lamp to a compact spectrometer. The molecular fluorescence resulting from the interaction of light emitted at the distal end of the hollow waveguide and the sample matrix is received and transmitted to a CCD via a compact dispersive grating-prism (grism) optical assembly. A linear array of the coaxial optical fibers permits a full excitation-emission matrix spectrum of the analyte matrix to be projected onto the face of the CCD. The in situ identification and monitoring of polycyclic aromatic hydrocarbons was carried out for the initial application testing for this prototype.
Optofluidic Lab-on-a-Chip Fluorescence Sensor Using Integrated Buried ARROW (bARROW) Waveguides
Micromachines
Optofluidic, lab-on-a-chip fluorescence sensors were fabricated using buried anti-resonant reflecting optical waveguides (bARROWs). The bARROWs are impervious to the negative water absorption effects that typically occur in waveguides made using hygroscopic, plasma-enhanced chemical vapor deposition (PECVD) oxides. These sensors were used to detect fluorescent microbeads and had an average signal-to-noise ratio (SNR) that was 81.3% higher than that of single-oxide ARROW fluorescence sensors. While the single-oxide ARROW sensors were annealed at 300 • C to drive moisture out of the waveguides, the bARROW sensors required no annealing process to obtain a high SNR.