Periodontal pocket depth measurements by fiber optic technology.
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Fiber Optic Technology↗
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Development and evaluation of a new body-seat interface shape measurement system.
A new system has been developed to capture the body-seat interface shape. It can repeatedly and accurately measure interface deformation. The shape sensing array system uses optical fiber technology and is noninvasive. The system can cover an interface as large as 400 x 480 mm and the shape is measured over a 10 x 12 array of sensors laminated on ribbon substrates. The accuracy and repeatability of this system were assessed. Measurement errors were evaluated by comparing the shape with a reference shape obtained by a mechanical digitizer. The root-mean-square error in the Z direction for the system was 3.79 mm. The repeatability of the system was within 0.38 mm under controlled conditions. Different interface materials noticeably affected measurements. With the development of this interface shape measurement device, the basic information gathered through its use may prove to be fundamental in the successful design of generic-shape contoured support surfaces. Furthermore, we expect that the new shape measurement device will provide a quick and effective tool for cushion evaluation and clinical guidelines for cushion prescription.
Algorithms↗
Light scattering from cervical cells throughout neoplastic progression: influence of nuclear morphology, DNA content, and chromatin texture.
A number of noninvasive fiber optic optical technologies are under development for real-time diagnosis of neoplasia. We investigate how the light scattering properties of cervical cells are affected by changes in nuclear morphology, DNA content, and chromatin texture, which occur during neoplastic progression. We used a Cyto-Savant computer-assisted image analysis system to acquire quantitative nuclear features measurements from 122 Feulgen-thionin-stained histopathologic sections of cervical tissue. A subset of the measured nuclear features was incorporated into a finite-difference time-domain (FDTD) model of cellular light scattering. The magnitude and angular distribution of scattered light was calculated for cervical cells as a function of pathologic grade. The nuclear atypia strongly affected light scattering properties. The increased size and elevated DNA content of nuclei in high-grade lesions caused the most significant changes in scattering intensity. The spatial dimensions of chromatin texture features and the amplitude of refractive index fluctuations within the nucleus impacted both the angular distribution of scattering angles and the total amount of scattered light. Cellular scattering is sensitive to changes in nuclear morphology that accompany neoplastic progression. Understanding the quantitative relationships between nuclear features and scattering properties will aid in the development of noninvasive optical technologies for detection of precancerous conditions.
Cell Nucleus↗
Chronic total occlusions: experience with fiber-optic guidance technology--optical coherence reflectometry.
Chronic total occlusions are difficult to treat and continue to challenge the interventional cardiologist. The primary difficulty is safely crossing the total occlusion with a guidewire before any revascularization can begin. One of the main reasons conventional and newer guidewires have not proven effective is simply the lack of visualization to safely steer the guidewire across the occlusion. This limitation can be overcome with new technology using a "forward-looking" fiber-optic guidance. The Safe-Steer TO (Total Occlusion) Crossing System is a new guidance system that uses optical coherence reflectometry to steer a guidewire through total occlusions. Optical coherence reflectometry uses algorithms to determine tissue types (plaque vs arterial wall) by measuring the intensity of the reflection of near-infrared light. The authors' clinical experience with the Safe-Steer System has met considerable success. With their initial 28 patients (7 women, 21 men) with known chronic total occlusions and confirmed ischemia, the primary success rate for the crossing the occlusion was 86% (24/28 cases). The average occluded lesion length was 41.1 +/- 30.8 mm. Our initial clinical experience demonstrates that the optical guidewire is a viable technology in the treatment of chronic total occlusions.
Adult↗
[Optical oxygen sensor based on a sol-gel encapsulation method].
OBJECTIVE: To develop oxygen sensor by use of sol-gel encapsulation method and optical fiber technology. Method Organically modified sol-gel film was prepared by hydrolyzing tetraethoxysilane (TEOS) and methyltriethoxysilane (MTEOS) together, and film-processing conditions were optimized. Overall validation of the method was carried out by building Stern-Volmer plots and determining the concentration of oxygen in samples. RESULTS: The optical fiber oxygen sensor was linear in a wide range (oxygen gas: 0%-100% and dissolved oxygen: 0.55 mg/L-33.1 mg/L 29 degrees C, r > 0.9990) and had a fast response time (T95 < 20 second). Signals were steady and not easily interfered. The results of measuring oxygen in samples by using the oxygen sensor and iodimetry respectively were compared and no significant difference was found. CONCLUSION: The sensor system is applicable to continuous measurement of gas phase oxygen and dissolved oxygen on line in a complex rigorous conditions.
Biosensing Techniques↗
Fiberoptic biosensors in artificial organs.
A large variety of assay methods based on optical principles can be miniaturized and adapted for use as in vivo monitors with the currently available optical fiber technology. Especially exciting is the capability of adapting the selectivity of immunoassays to continuous on-line biosensors by the use of hollow dialysis fibers. Thus, one can envision biosensors that could have many different applications in artificial organ development, from passive systemic monitoring to active feedback control devices for drug delivery.
Artificial Organs↗
Use of fiber-optic pressure transducer for intracranial pressure measurements: a preliminary report.
Invasive monitoring of intracranial pressure (ICP) is becoming the standard of care for management of acute neurologic and neurosurgical patients. As a result of improved fiber-optic technology, a new disposable 4 French fiber-optic transducer-tipped catheter (FTC) has been introduced for facilitating measurement of intracranial pressure. Placement of the FTC can be intraventricular, subarachnoid, subdural, or intraparenchymal. Sensitivity and linearity of each catheter are manufacturer calibrated and not adjustable. Zero or atmospheric balance is done only once before insertion. Because the transducer is the catheter tip, no leveling to an anatomic point is necessary. The system appears to eliminate some of the difficulties inherent in fluid-filled catheter monitoring. In clinical trials, the comparison of FTC with subdural and ventriculostomy waveforms and pressures showed essentially no difference. Pressure recordings tracked well except during transient periods of increased ICP, when FTC showed higher peak pressures. Use of the FTC requires education regarding placement and maintenance techniques. Although staff experience with the catheter can practically eliminate the problem, the FTC catheters need special handling because of potential for fiber breakage.
Catheterization↗
[Fiber optic sensor technology in the endotracheal tube].
The measurement of individual respiratory parameters in the vicinity of the lungs remains an unresolved problem in the areas of anesthesia and intensive care medicine. New technologies such as fibreoptic technology, which meet the extreme demands of medical sensor applications, and their innovative potential as a basis for the development of marketable products, appear promising. This is illustrated by the fundamental principles developed for a sensor-armed tracheal tube for on-line monitoring of ventilated patients.
Anesthesia, Endotracheal↗
Spectral multichannel monitoring of radiation within a mature mixed forest.
A multi-sensor system is described based on fiber optic technology and a diode array spectrometer for near-simultaneous measurement of spectral photon fluence rates (PFR) in the range of 360 nm to 1020 nm with a resolution of 0.8 nm, within a mature Norway spruce ( Picea abies [L.] Karst.) - European beech ( Fagus sylvatica L.) stand. 126 space-integrating spherical sensors, deployed in a regular grid above and within the canopy and on the forest floor, are sequentially connected to the spectrometer by means of fiber optics. About 1 s per sensor is needed to collect spectral data, store them on hard disk and move the channel multiplexer to the next fiber optic position. Data thus obtained serve to determine vertical profiles of wavelength-dependent photon extinction, especially for spectral ratios and wavebands, characterization of phenological stages, analyses of time series, and meteorological influences such as solar altitude and cloud cover. First measurements during leaf fall 2004 show a non-linear relation of the red/far-red ratio (R/FR) with relative photosynthetic PFR (PPFR (rel)). An analysis of relative PFR (PFR (rel)) quantifies the frequency of penumbral sunfleck occurrence and the fraction of incoming radiation on the forest floor. In-canopy measurements of daily means of PPFR (rel) and R/FR indicate that leaf unfolding and leaf fall can be described by a single sensor, independent of its vertical location within the canopy.
Circadian Rhythm↗
Toward virtual biopsy through an all fiber optic ultrasonic miniaturized transducer: a proposal.
The present generation of devices based on opto-acoustic and acousto-optic conversion lets us foresee the possibility of realizing complete miniaturized transmitting-receiving transducers, able to generate and detect wideband ultrasounds by laser light. In the present paper, a miniaturized ultrasonic transducer entirely based on fiber optic technology is proposed. Such a device springs from the conjunction between our research, which has produced a highly efficient fiber optic opto-acoustic source, with the results obtained by other researchers concerning the realization of an ultrasonic receiver based on optical interferometry. Making use of the thermo-elastic effect for ultrasound generation, a source of ultrasound can be obtained by coupling a fiber optic to pulsed laser, if a film capable of absorbing laser light is placed onto fiber end. Starting from these remarks, we propose an efficient opto-acoustic source, able to generate pressure pulses with amplitude of the order of 10(4) Pa and bandwidth extending up to 40 MHz and beyond by using graphite materials as absorbing film. This solution makes use of a low-power pulsed laser as optical source possible. An ultrasonic receiving element was realized placing a Fabry-Perot cavity over the tip of a fiber optic. The cavity thickness modulation induced by ultrasonic beam is detected by an interferometer optical technique. We have realized a prototype of a receiving device that exhibits a sensitivity comparable with that of piezoelectric devices (10-100 nV/Pa) and an almost flat bandwidth extending up to 20 MHz or more. The extreme miniaturization of the resulting ultrasonic transducer, together with its wide ultrasonic frequency bandwidth, is the first step toward ultrasonic tissue biopsy. In this paper, before discussing the problem of constructing a complete ultrasonic transducer composed by a transmitter and receiver, the results carried out in these fields during the last decade are reviewed.
Biopsy↗
Simple fiber-optic-based sensors for process monitoring: an application in wine quality control monitoring.
The goal of this research was to develop a simple and economical fiber-optic sensor technology for agrifood process monitoring. Toward this end, two fiber-optic sensors were developed to be used in combination: a single reflection V-bend sensor and a single fiber air-gap probe. The former is designed to be sensitive toward refractive index and the latter towards absorption. Experiments indicate that the micromachined V-bend fiber refractometer is most sensitive when the bend angle is centered around 140 degrees, at which angle the sensor may resolve changes in refractive index as small as 0.00015. Additionally, the V-bend sensor was found to be non-responsive toward sample absorption even in extremely absorbing solutions. The air-gap design absorption sensor, most commonly used for measurements in highly colored media, was found to be slightly sensitive towards refractive index. When the two sensors are used together, the response of the absorption sensor may be corrected for. This sensor combination is able to provide accurate measurements in situations where Beer's law is not obeyed. Results are presented that show that the sensor pair was successfully used to monitor wine sugar content (Brix), and color density and hue, parameters related to the age of the wine.
Absorption↗
Evaluation of the fiber-optic antibody-based fluoroimmunosensor for DNA adducts in human placenta samples.
This paper presents the application of a fiber-optic antibody-based fluoroimmunosensor (FIS) for measuring DNA adducts of benzo[alpha]pyrene in human placenta samples. The FIS combines the excellent specificity of the antigen-antibody reaction, the high sensitivity of laser excitation, and the versatility of fiber-optic technology. The FIS was used to detect benzo[alpha]pyrene tetrol (BPT) after release from DNA by mild acid hydrolysis. These placenta samples contained one molecule of adduct per 10(7) base pairs. The limit of detection of the FIS for BPT is about 14 amol (14 x 10(-18) mol).
Benzo(a)pyrene↗
Percutaneous angioscopy. Work in progress.
The cardiovascular applications of flexible fiber-optic technology are imminent because of recent advances in miniaturization. In the work described here, angioscopy, or vascular endoscopy, was performed in the cadaveric aorta and in the systemic and pulmonary circulations of the canine model and selected human patients. Subsequent to our development of percutaneous techniques, clinical trials have ranged from lower-extremity venoscopy to aortic-root arterioscopy. Angioscopy could be clinically useful because of relative or absolute contraindications to iodinated contrast material. The ability to see in color and three dimensions may afford some other advantages to angioscopy over conventional angiography.
Animals↗
In vivo and in situ detection of colorectal cancer using Fourier transform infrared spectroscopy.
AIM: Real-time and rapid identification of the malignant tissue can be performed during or before surgical operation. Here we aimed to detect in vivo and in situ colorectal cancer by using Fourier transform infrared (FTIR) spectroscopy and fiber-optic technology. METHODS: A total of five patients with large intestine cancer were detected in vivo and in situ. Of them, three cases of colon cancer and one case of cecum cancer were detected intraoperatively and in vivo by using a FTIR spectrometer during surgical operation, and one case of rectum cancer was explored non-invasively and in vivo before the surgical operation. Normal and malignant colorectal tissues were detected in vivo and in situ using FTIR spectroscopy on the basis of fundamental studies. RESULTS: There were significant differences between FTIR spectra of normal and malignant colorectal tissues detected in vivo and in situ. Experimental results revealed that the spectral characteristics of normal and malignant tissues found in vivo and in situ were similar to those obtained from in vitro measurement in our previous fundamental research. CONCLUSION: FTIR fiber-optic attenuated total reflectance (ATR) spectroscopy can identify in situ and in vivo colorectal cancer. FTIR spectroscopic method with fiber optics is a non-invasive, rapid, accurate and in vivo cancer detection technique in clinical diagnosis.
Aged↗
Rural connections. Iowa hospitals are establishing communications link to better serve rural areas.
The Sisters of Mercy Health Corporation, with 14 hospitals in Iowa, and the Mercy Health Centers of Central Iowa, with 13 hospitals in the state, believe fiber-optic technology may provide solutions to the inadequacies inherent in the rural healthcare delivery system. Since 1989, Iowa has committed more than $100 million toward the development and installation of a statewide fiber-optic communication network. The Iowa Communication Network (ICN) was originally envisioned as a means of providing voice, data, and interactive video capabilities to state government agencies, libraries, schools, and colleges. Currently, only hospitals with medical education programs are authorized to use the network, but others are expected to be allowed to soon. Realizing the potential benefits telemedicine and the ICN posed, in June 1993 the Sisters of Mercy Health Corporation and the Mercy Health Centers of Central Iowa jointly established the Midwest Rural Telemedicine Consortium (MRTC) to enhance rural residents' access to primary healthcare through integrated communications systems. The MRTC is trying to secure federal funding to conduct a demonstration project in eight hospitals. The project's goal is to determine how the use of telemedicine applications, specifically fiber-optic applications, affects access, quality, and costs in providing specialty healthcare services to rural patients.
Catholicism↗
Instrumentation for urologic laser surgery.
Carbon dioxide, neodymium:yttrium-aluminum-garnet, ruby, and argon lasers are the only commercially available lasers with wavelengths suitable for laser surgery. Consequently, researchers have attempted to make the tool fit the clinical need. A pediatric #6 bronchoscope was fitted to a carbon dioxide laser endoscopic coupler to form a modified cystoscopic laser delivery system. This instrument was able to vaporize small condylomata of the distal male urethra. However, the restricted visibility of this crude adaptation represents an inferior solution compared with the endless possibilities of sophisticated fiberoptic technology. Future prospects in infrared optical fiber technology portend a breakthrough for transurethral carbon dioxide laser surgery. Adapting the Nd:YAG laser for urologic surgery is attractive because it can be easily incorporated into conventional cystoscopes. The argon laser's capacity to absorb blood and traverse water suggests future importance for transurethral surgery. Investigation is needed to develop a surgical laser adaptable to both open and transurethral urologic surgery.
Argon↗
A novel method for detecting licking behavior during recording of electrophysiological signals from the brain.
We have developed a novel method for detecting licking at a fluid well that is compatible with behavioral neurophysiology. This method uses off-the-shelf fiber optic technology to introduce a light beam through the fluid-air interface of a fluid bolus in a well. A self-adjusting optical sensor detects licking as disturbances in the amplified light surface within the interface when the fluid is disturbed. The proper configuration of fluid well and fiber optics will reliably detect licking and introduce no artifacts into simultaneous high-impedance recordings of extracellular neural activity. This method is also compatible with delivery of multiple fluids to the same well. Unlike present methods of detecting licking in neurophysiological experiments, our approach does not involve the passage of current or capacitance changes in which the animal forms part of a circuit, nor does it require movement of the licking apparatus or any other response beyond the actual licking of the fluid. As a result, noise artifacts in the unit recordings do not occur, and the sensor is highly resistant to artifacts caused by exploration or licking at the fluid well in the absence of liquid. We present neural recording data from units in the nucleus accumbens demonstrating these properties of the lick detector.
Animals↗
Effect of polishing conditions on terminating optical connectors with spherical convex polished ends.
Increased demand for fiber-optic technology has created significant growth in the sales of interconnection devices such as fiber-optic connectors, cable assemblies, and adapters. To ensure good connector performance during actual use, several process parameters related to geometric and optical characteristics of the connector must be thoroughly understood during the manufacturing stage. The experimental design has been used here to see the influence of applied pressure and time on the fiber end geometry as well as optical performance. The mathematical model is also applied to explain the phenomena of the present fiber undercut-reflectance relation. By a proper choice of polishing film grit size and processing conditions, it is possible to obtain fiber connectors with less fiber undercut and better return loss. Influences of film grit size and rubber-pad thickness on the reflectance and the fiber undercut are also presented.
Journal Article↗