Fiber sensors

Photodiode (LED) Pin photodiode Cameras, strobes, illuminators, remote controls, IR sensors Fiber-optic communications, liber links... 

Beyer T., Hahn P., Hartwig S., Konz W., Scharring S., Katzir A., Steiner H., Jakusch M., Kraft M., Mizaikoff B.,, Mini spectrometer with silver halide sensor fiber for in situ detection of chlorinated hydrocarbons, Sensors Actuators B, 2003 90 319 - 323. 

The most common shape of the sensor fiber tip is the flat one. It is easy to prepare, since only a fiber cutter is needed. However, the bounding of optode is not very robust and it can be destroyed mechanically. 

Embedded sensors Fiber optic sensors H2O, H2, 02, Signal is unaffected by electric fields, should minimally affect cell performance Currently an immature technology... 

Acetylcholineesterase A 350 pM diameter coherent imaging fiber coated on the distal surface with a planar layer of analyte-sensitive polymer that was thin enough not to affect the fiber s imaging capabilities. It was applied to a pH sensor array and an ACh biosensor array (each contain 6000 optical sensor). Fibers were coated with an immobilized layer of poly (hydroxyethylmethacrylate)-N-flurosceinylacrylamide and AChE-fluorescein isothiocyanate isomer poly (acryloamide-co-N-acryl oxysuccinimide), respectively. The response time of the pH sensor was 2 s for a 0.5 unit increase in pH. The biosensor had a detection limit of 35 pM ACh and a linear response in the range 0.1 mM. [90]... 

As a means of incorporating the fiber sensors into systems, incorporation of in-line fiber sensors into non-woven fabrics was explored. In order to incorporate an in-line sensor into a textile fabric, a spun-bonded base fabric was taken and an in-line fiber sensor was placed on top of it. Subsequently, non-woven fibers of polyurethane were electrospun on top of the optical fiber sensor to hold the sensor fiber in its position, thereby incorporating it in a non-woven fabric matrix. The electro-spinning was carried out at a voltage of 18 KV using a solution of polyurethane in the solvent DMP. 

Macedo PB, Barkatt A, Feng X, Finger SM, Hojaji H, Laberge N, Mohr R, Penafiel M, Saad E (1989) Development of porous glass fiber sensors, Fiber optic structures and smart skins. Proc SPIE 986 200-205... 

Leiner M J P and Wolfbeis O S 1991 Fiber optic pH sensors Fiber Optic Chemical Sensors and Biosensors vol 1, ed O S Wolfbeis (Boca Raton, FL Chemical Rubber Company) pp 359-84 Jackson J T and Hui H K 1993 US Patent 5 212092... 

Nelson A, Hui H K, Bennett M, Hahn S and Bankert C S 1993 US Patent 5 204 265 Wolfbeis O S 1991 Oxygen sensors Fiber Optic Chemical Sensors and Biosensors vol 2, ed O S Wolfbeis (Boca Raton, FL Chemical Rubber Company) pp 19-53 Hauenstein B L, Picemo R, Brittain H J and Nestor J A 1993 US Patent 5 190729 Modlin D N and Milanovitch F P 1991 Instrumentation for fiber optic chemical sensors Fiber Optic Chemical Sensors and Biosensors vol 1, ed O S Wolfbeis (Boca Raton, FL Chemical Rubber Company) pp 237-302 Wolthuis R, McCrae D and Hartl I C et al 1992 Development of a medical fiber optic oxygen sensor based on optical absorption change Trans. IEEE Eng. Biol. Med. EBM-39 185-93... 

The availability of low-cost, highly transmitting NIR fibers has led to the widespread application of NIR fiber sensors. Fibers may simply be used as a light guide between the NIR spectrometer and the measuring point, or they may serve as a sensor by using the evanescent field of light totally reflected inside... 

Photoelectric sensors commonly used in die protection include opposedmode sensors, fiber-optic sensors, convergent photosensors, diffuse reflective sensors, and minilight curtains. Diffuse reflective sensors and minilight curtains are typically used only for part ejection detection and are covered in a later section. 

What if any is the effect of connectivity on the behavior of the photochromic composite described in Section 9.4 in the following cases (a) a 0-3 composite isolated sensor particles in a three-dimensional actuator matrix (b) a 1-3 composite sensor fibers or whiskers in an actuator matrix and (c) a 2-2 composite sensor layers alternated with actuator layers. 

Pyruvate Corn kernei Pyruvate decarboxyiase CO2 gas sensor, fiber-optic CO2 sensor... 

The need for new structural and new sensor fibers is well known, but they cannot be made without extensive process and product research. In fact, each fiber would require its own lengthy process development before it could be evaluated in a minimum adequate composite or sensor application. Thus, the staggering cost of research precludes the development of new fibers. In this context, the HP-LCVD process has become an ideal tool for the rapid fabrication, without extensive process research, of test specimens of a variety of continuous length fiber candidates. These specimens can then be rapidly evaluated against the needs of a given end use long before a decision is needed if a new fiber should be commercialized by the LCVD process itself or by an adaptation of another fiber process. 

Potentially useful single crystal HP-LCVD fibers include hafnium boride and tantalum carbide and have projected service temperatures ranging from 2170 to 2715 C. Presently envisioned applications include the potential use of these fibers as consumable sensors to monitor rocket exhaust temperatures. Other HP-LCVD sensor fibers, including Si, Ge and ZnSe, (Figure 15), promise to offer high value in premium automotive and medical sensor systems. Single crystal HP-LCVD germanium [20] and silicon carbide [21] fibers can now also become available for exploration. In summary, the HP-LCVD process is an ideally suited tool for the rapid fabrication and evaluation, without extensive process research, of test samples of potentially new fiber candidates for structural and sensor uses. 

The economics and scalability of the new process are not known. The materials cost and the cost of operating a laser process are probably about the same for an amorphous YAG sensor fiber made by the containerless laser heated melt process and a for single crystal YAG sensor fiber made by laser heated pedestal growth (Chapter 4.5.2). And both are containerless processes. However the higher process speed may favor the laser heated melt process (1.5 m/s) over the laser heated pedestal process (1 mm/s). 

Capacitive sensors can be used to detect displacement from the fact that capacitance between two parallel metal plates, C = eoEt A/x, where eo = dielectric constant of free space, Cf = relative dielectric constant of media. Displacement can be measured by changing aU these three parameters. A good example is the capacitance microphone that is responding to displacement by sound pressure. Piezoelectric sensors are used to measure physiological displacement and record heart sounds. These sensors are fabricated from piezoelectric ceramics and piezoelectric polymers. For flexible wearable sensors, fiber or film form of polymer piezoelectric materials such as polyvinyli-dene fluoride (PVDF) are desirable. 

Parameters to be varied by the measurand are the intensity, the wavelength or phase, and the polarization state of light. Additionally used is, by means of optical time-domain reflectometry (OTDR) technique, the measurement of the travel-time of a light pulse launched at one fiber end and backre-flected at markers. From measurement of the time of transit, the shortening or extension of the optical path length (contraction or extension of the sensor fiber) can be assessed. However, any effects influencing the fiber can be located. It should be noted that a considerable number of fiber optic sensor types has been created in the past decades for measurement of almost all physical, and a lot of chemical, quantities. 

Fiber-Optic Fluorescence Sensors Fiber-optic probes have been used to demonstrate that several fluorescence determinations can be carried out at various locations well awav from a source and a... 

Compared to the conventional mechanical and electrical/electronic humidity sensors, fiber-optic based humidity sensors [6, 14], including silica glass fiber and polymer optical fiber (POP) based sensors [28, 46], demonstrate many unique advantages, such as small size and low weight, immunity to electromagnetic interference, corrosion resistance, potentials for remote operation and distributed sensing. In fiber-optic sensor family, the fiber grating... 

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