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At least 37 records · Page 2Linked to original sources
PubMed2005

Individual cell migration analysis using fiber-optic bundles.

In this paper we describe a novel optical fiber-based technology for analyzing cell migration. Cells were labeled with a membrane-bound fluorescent dye and distributed onto a polished optical fiber bundle. When a cell passes over one of the individual fibers in the bundle, the membrane-bound dye causes a large intensity increase, which stays for a given "residence time" until the cell departs from the fiber. Residence time increases significantly upon exposure to an antimigratory drug, indicating a decrease in cell migration. This approach provides a simple migration assay and does not require sophisticated tracking software. By using optical fiber bundles containing smaller individual fibers with higher spatial resolution, this approach was employed to develop a migration assay based on subcellular imaging. The subcellular imaging platform allows for rapid analysis of migratory potential, reducing experimental time from several hours in a standard assay to 5 min using this technology.

Cell Movement↗
PubMed2000

Quantitative real-time monitoring of dryer effluent using fiber optic near-infrared spectroscopy.

This paper describes a method for real-time quantitation of the solvents evaporating from a dryer. The vapor stream in the vacuum line of a dryer was monitored in real time using a fiber optic-coupled acousto-optic tunable filter near-infrared (AOTF-NIR) spectrometer. A balance was placed in the dryer, and mass readings were recorded for every scan of the AOTF-NIR. A partial least-squares (PLS) calibration was subsequently built based on change in mass over change in time for solvents typically used in a chemical manufacturing plant. Controlling software for the AOTF-NIR was developed. The software collects spectra, builds the PLS calibration model, and continuously fits subsequently collected spectra to the calibration, allowing the operator to follow the mass loss of solvent from the dryer. The results indicate that solvent loss can be monitored and quantitated in real time using NIR for the optimization of drying times. These time-based mass loss values have also been used to calculate "dynamic" vapor density values for the solvents. The values calculated are in agreement with values determined from the ideal gas law and could prove valuable as tools to measure temperature or pressure indirectly.

Calibration↗
PubMed2003

Optical-fiber-based Mueller optical coherence tomography.

An optical-fiber-based multichannel polarization-sensitive Mueller optical coherence tomography (OCT) system was built to acquire the Jones or Mueller matrix of a scattering medium, such as biological tissue. For the first time to our knowledge, fiber-based polarization-sensitive OCT was dynamically calibrated to eliminate the polarization distortion caused by the single-mode optical fiber in the sample arm, thereby overcoming a key technical impediment to the application of optical fibers in this technology. The round-trip Jones matrix of the sampling fiber was acquired from the reflecting surface of the sample for each depth scan (A scan) with our OCT system. A new rigorous algorithm was then used to retrieve the calibrated polarization properties of the sample. This algorithm was validated with experimental data. The skin of a rat was imaged with this fiber-based system.

Animals↗
PubMed1996

Cylindrical fiberoptic light diffuser for medical applications.

BACKGROUND AND OBJECTIVE: A cylindrical light diffuser has been developed mainly for medical applications, including photodynamic therapy (PDT), in particular interstitial PDT, PDT of the bronchi, or intravascular PDT. STUDY DESIGN/MATERIALS AND METHODS: The diffuser is based on a polymer optical fiber. The coupling of the light out of the core is controlled by the roughness mechanically induced on the surface of the core. The light is then isotropically diffused by a thin layer of a scattering medium. The active length can be 100 mm or more, whereas the outer diameter is 1 mm or less. The diffuser is flexible and can be introduced in tissue though a hypodermic needle. RESULTS: The main property of this light diffuser is the homogeneity of the light intensity emitted along its whole active length and around its circumference (360 degrees). Various intensity profiles can be made, including M-shape profiles for a homogeneous irradiance (+/- 10%) at a certain depth in the tissue. Furthermore, the diffuser is essentially isotropic and its optical properties are hardly dependent on wavelength. CONCLUSIONS: A diffuser for interstitial and intraluminal PDT has been developed. It is flexible, homogeneous, independent on wavelength, and can be made with a very high length-to-diameter ratio.

Fiber Optic Technology↗
PubMed1999

Fiber optic Z-cell for CZE.

Fiber optic Z-cell for CZE was designed, constructed, tested and compared with on-column detection. Ten times higher sensitivity for Z-cell in comparison with on-column detection was achieved as expected from optical pathlength ratio. Linear dynamic range was > 4 orders of magnitude for both cells.

Electrophoresis, Capillary↗
PubMed2006

Proof-of-concept of a novel micro-bioreactor for fast development of industrial bioprocesses.

The experimental performance of a novel micro-bioreactor envisaged for parallel screening and development of industrial bioprocesses has been tested in this work. The micro-bioreactor with an internal volume of 4.5 mL is operated under oscillatory flow mixing (OFM), where a controllable mixing and mass transfer rates are achieved under batch or continuous laminar flow conditions. Several batch fermentations with a flocculent Saccharomyces cerevisiae strain were carried out at initial glucose concentrations (S(0)) range of approximately 5-20 g/L and compared to yeast growth kinetics in a stirred tank (ST) bioreactor. Aerobic fermentations were monitored ex situ in terms of pH, DO, glucose consumption, and biomass and ethanol production (wherever applicable). An average biomass production increase of 83% was obtained in the micro-bioreactor when compared with the ST, with less 93.6% air requirements. It also corresponded to a 214% increase on biomass production when compared with growth in a shaken flask (SF) at S(0) = 20 g/L. Further anaerobic fermentations at the same initial glucose concentration ranges gave the opportunity to use state-of-the-art fiber optics technology for on-line and real-time monitoring of this bioprocess. Time profiles of biomass concentration (measured as optical density (OD)) were very similar in the ST bioreactor and in the micro-bioreactor, with a highly reproducible yeast growth in these two scale-down platforms.

Biomass↗
PubMed1996

Multiple capillary DNA sequencer that uses fiber-optic illumination and detection.

An 8-capillary prototype electrophoresis system for DNA sequencing has been constructed. The sequence of 400-450 bases can be obtained from each capillary in less than an hour from sequencing reactions generated with four-color fluorescent terminators. Illumination of each capillary and collection of fluorescence is through individual optical fibers. Resolution of the DNA ladder is through a replaceable sieving matrix of linear polyacrylamide in reusable coated capillaries. Light from an argon ion laser is introduced into a fused biconically tapered fiber-optic splitter, and individual fibers deliver approximately 10 mW of 514 nm light to each of the eight electrophoresis capillaries. Illumination and collection are by fibers normal to the surface of the electrophoresis capillary and at right angle to each other. Illumination by a fiber with low numerical aperture and collection by a fiber with high numerical aperture provides good sensitivity and signal-to-noise ratios without the need for microlenses (limit of detection: 1.5 x 10(-11)M fluorescein analog dye with a signal-to-noise ratio of 2). The eight collection fibers are passed in parallel through holographic filters for Rayleigh rejection and into an imaging spectrograph, which simultaneously displays the full fluorescence spectrum (475-648 nm) from the eight capillaries in parallel on the surface of an intensified charge-coupled device (CCD). The CCD is read out at a rate of 3.4 complete images per second.

DNA↗
PubMed1995

A robotic dissolution system with on-line fiber-optic UV analysis.

An automated, robotic system has been developed with on-line UV fiber optics for real time dissolution analysis of solid dosage forms. The system is comprised of "off-the-shelf" hardware including a UV-Vis diode array spectrophotometer, fiber optic coupler, immersion probe, robot, and dissolution apparatus. The software system is modular with the functionalities of control, data acquisition, and spectral analysis separated into three Windows applications with communications performed via Dynamic Data Exchange (DDE). The fiber optic spectrophotometer collects a full spectrum over the range of 190-810 nm. Single wavelength UV analysis is performed on dosage forms in six dissolution vessels. The robotic system automates all facets of the analyses: measuring, degassing, and dispensing of the media; thermostating the media to physiologic temperature; dropping the dosage forms into the vessels; immersing the fiber optic probe at the appropriate time intervals; initiating the data acquisition, analyses, and reporting; and emptying and washing of the vessels prior to the next automated run. As a representative dosage form, 10 mg active tablets were selected and analyzed by this method. This fiber optic system has significantly improved the throughput of the robotic systems by eliminating the need for time consuming off-line HPLC or UV analyses. In addition, with the exception of system calibration, it is no longer necessary for laboratory personnel to come in contact with samples.

Chemistry, Pharmaceutical↗
PubMed1978

A fiberoptic reflection oximeter.

A catheter tip oximeter is described consisting of a cardiac catheter containing optical fibers, and incandescent light source, a light detection unit and a processing unit. Half of the optical fibers guide the light to the blood at the tip of the catheter, the other half the backscattered (reflected) light to the detection unit. The detection unit contains a dichroic mirror, transmitting most of the light with lambda less than 800 nm and reflecting most of the light with lambda greater than 900 nm, thus splitting the light into two beams. These pass through interference filters with nominal wavelengths of 640 and 920 nm respectively, and are focused on silicium barrier layer photocells. The photocell signals are amplified and fed into a divider giving the ratio of measuring (R640) and compensating (R920) photocell output. The relationship between log R640/R920 and oxygen saturation is represented by a slightly curved line. The relation may be linearized by subtracting a constant voltage from the divided output before taking the logarithm. The slope of the calibration line is dependent on the total haemoglobin concentration. Nonetheless an average calibration line can be used between 70 and 100% oxygen saturation. For 78 measurements of pig blood samples in this range (haemoglobin concentration between 96 and 161 g.1(-1)), the standard deviation of the difference between the fiberoptic oximeter and a Radiometer OSM1 oxygen saturation meter was 1.9% saturation, for 152 samples over the entire saturation range the standard deviation of the difference was 3.1% saturation. The influence of the flow velocity of blood on the light reflection depends on wavelength as well as on oxygen saturation. Therefore, complete compensation for the flow effect is not possible by simple means.

Animals↗
PubMed1983

Multi-electrode recording system for the study of spatio-temporal activity patterns of neurons in the central nervous system.

A new type of recording microelectrode with mechanical and electrical properties suitable for use in microelectrode assemblies for neurophysiological studies in the central nervous system was developed by adaptation of principles from optical fiber technology. A microdrive for independent positioning of up to 7 electrodes for the recording of electrical activity from individual neurons was constructed. It operates by the combined action of a stepping motor and a system of independently controllable piezoelectric clutches and brakes for each electrode.

Central Nervous System↗
PubMed1983

A fiber optic PCO2 sensor.

The theory, construction and performance of a catheter tip optical PCO2 probe is described. The sensor, called the Opticap, is made with plastic fiber optics. One fiber carries light to the sensitive tip which is a silicone rubber tube 0.6 mm dia. X 1.0 mm long filled with a phenol red-KHCO3 solution. Ambient PCO2 controls the pH of the solution which influences the optical transmittance of the phenol red. A second fiber carries the transmitted signal to a receiver; the resulting electrical signal is linearly related to the PCO2 over the range of 2.7 to 10.7 kPa. The probe was tested as a tissue PCO2 sensor on the cerebral cortex of the cat and as an arterial PCO2 sensor. Drift over one day's use was 0.6 KPa or less and individual probes have been used as long as 12 weeks.

Animals↗
PubMed2006

Development of a fiber optic enzymatic biosensor for 1,2-dichloroethane.

There is a significant need for devices capable of measuring water contaminant concentrations in situ--continuously, rapidly, and without reagents, extraction, or other pretreatment. Toward this goal, we constructed and tested fiber optic biosensors for measurement of 1,2-dichloroethane (DCA) in aqueous solutions. The biocomponent was the haloalkane dehalogenase, DhlA, in whole cells of Xanthobacter autotrophicus GJ10. These cells were immobilized in calcium alginate on the tip of a fiber optic fluoresceinamine-based pH optode. The resulting biosensor could quantify DCA at 11 mg/l and had a linear response up to at least 65 mg/l. Total signal change was reached in 8-10 min, and measurements were reproducible (SE <9%). The sensor's small size, potential for remote operation, and low cost make it of interest for further development.

Biosensing Techniques↗
PubMed1992

Colorimetric determination of free and total cholesterol by flow injection analysis with a fiber optic detector.

A flow injection method for the determination of total and free cholesterol is presented. Cholesterol esterase and cholesterol oxidase are immobilized on aminoalkyl glass beads. The beads are packed into a tubular glass reactor. The cholesterol esters traversing through the esterase reactor are cleaved to cholesterol and fatty acids. The oxidase reactor converts cholesterol to cholest-4-en-3-one and hydrogen peroxide is generated. The sample stream is merged with reagent streams consisting of a peroxidase solution and a solution of 2,2'-azino-bis-(3-ethyl-benzthiazoline-6-sulfonic acid) diammonium salt, and a hydrogen peroxide-dependent color reaction takes place in a short coiled reactor. The signal is monitored by means of fiber optic instrumentation. Cholesterol concentration can be related to the absorption of the oxidized dye form at a wavelength of 425 nm. The working range is 0.5-0.8 mmol l-1, and the sample throughputs are 60 and 30 h-1 for free and total cholesterol, respectively.

Cholesterol↗
PubMed1980

Reflectance of rat brain structures mapped by an optical fiber technique.

A method to detect differences in reflectance as a pair of glass fibers is advanced through various brain structures at a constant speed is described. The system has been used to develop a technique for accurate and easy placement of electrodes or cannulae into a limited brain region. The probe consisted of two thin (50 micrometer in diameter) glass optic fibers. A 5 W lamp was used to transmit light down one of these fibers. The relative intensity of light reflected from brain tissue into the other optic fiber was monitored with a photomultiplier and ink-writing recorder. Different brain structures were shown to vary in the amount of reflectance, with white matter having much higher reflectance than gray matter. It was demonstrated in a total of 239 penetrations that the patterns of successive changes in the reflected light response, as the probe was lowered into the brain, was characteristic for each frontal plane. The probe may additionally be itself used as an electrode if plated with silver.

Animals↗
PubMed1982

Inexpensive fiber optic two-dimensional densitometer for the high-resolution quantitation of autoradiogram grain densities.

The design and construction of a simple, low cost high performance fiber optic 2-dimensional microdensitometer is described. With this instrument the film to be quantitated is placed upon a back-lit frosted glass bench and scanned with an optic fiber probe attached to a transparent micromanipulator. The emerging light is transported by the fiber to the photocell of a direct reading spectrophotometer. The resulting numerical data can either be transcribed, portrayed on a recorder or entered into the memory of a microdata processor for further analysis and comparisons. The instrument was sensitive to very small differences in optical density and could resolve lines 100 but not 30 micrometers apart. It was precise, reliable and easy to build. With the use of this equipment many previously undetected, significant local brain glucose utilization differences were quantitated in groups of unrestrained rodents, maintained in several behavioral states.

Animals↗
PubMed1994

Characterization of ultrasonic transducers using a fiberoptic sensor.

The PVDF (polyvinylidene fluoride) hydrophones, commonly used to measure the characteristics of ultrasonic transducers, suffer from a number of drawbacks. They disturb the field distribution to be measured and cause spatial averaging effects because of their finite aperture. In addition, they are very delicate and susceptible to damage. To overcome some of these problems, the authors previously proposed the use of an optical fiber-based probe to measure the ultrasonic fields. In this paper, this fiberoptic ultrasonic sensor is used to measure the characteristics of six transducers, focused as well as unfocused, covering a frequency range of 2.25 MHz to 20 MHz. Results obtained using the fiberoptic sensor are compared with those obtained using a calibrated PVDF needle hydrophone with an effective diameter of 0.5 mm. The temporal responses as well as the beam profiles of the transducers measured using the fiberoptic sensor show excellent agreement with the results obtained using the PVDF needle hydrophone.

Fiber Optic Technology↗