As a coating material for the dielectric-coated metallic hollow glass waveguides, a new kind of cyclic olefin polymer (COP-E48R) has been selected. Silver hollow glass tubes coated by this polymer have been successfully fabricated with the length of 2 m and the inner diameter of 1 mm, 700 micrometers , and 540 micrometers , respectively. When the thickness of the COP-E48R layer is properly selected, mid-infrared laser light of CO₂, CO, and Er:YAG as well as near infrared Nd:YAG laser has been transmitted with small attenuation. Straight losses of 0.1 to 0.25 dB/m were obtained for Nd:YAG, Er:YAG, CO, and CO₂ laser light for the waveguides with the inner diameter of 1 mm. Bending losses of these waveguides were also evaluated for the above laser light.

The transmission properties of four different waveguides were investigated: (1) dielectric coated silver hollow glass waveguides, with diameters varying from 0.7 mm to 1 mm, (2) polyamide waveguides, with diameters varying from 0.7 mm to 1 mm, (3) a silica glass waveguide, with a 0.7 mm diameter and (4) a plastic waveguide, with a 0.7 mm diameter. Two different lasers were used for the evaluation of these waveguides: (1) a pulsed Er:YAG laser, emitting at 2.96 micrometers and (2) a corona preionized pulsed HF laser, emitting at 2.78 micrometers . Both straight and bent loss characteristics of the waveguides were studied.

The influence of the adipose tissue thickness on near- infrared spectroscopy to monitor the hemodynamics in muscles in investigated. It is shown by calculation of the mean optical pathlength of two-layered turbid media that the validity of the modified Beer-Lambert law is reduced with increasing thickness of the first layer (fat), because the assumption, that the mean optical pathlength is constant, is not fulfilled. In order to avoid these problems we demonstrate that it is possible to derive the optical properties of both layers from time-resolved reflectance measurements using a solution of the two-layered diffusion equation if the thickness of the first layer is known.

A pulsed Er:YAG laser and a preionized pulsed HF laser were used for the evaluation of the transmission properties of sapphire fibers and fluoride glass fibers. Both lasers provided an output of 100 mJ/pulse, with a repetition rate of 1Hz at 3 micrometers wavelength. The pulse duration of the two lasers was 200 ns for the HF and 80 microsecond(s) for the Er:YAG. The sapphire fibers were 0.25 m long with diameters varying from 585 to 850 micrometers . The fluoride fibers were flexible, 1.6m long, with inner diameters varying from 350 to 600 micrometers . The evaluation of the fiber properties include both straight and bend loss characteristics, the influence of the input power to the output power and the permitted misalignment of the fiber in respect to the optical axis.

A CO₂ laser device based on a scanner Silver halide infrared (IR) optical fiber was designed and constructed. Power delivery was performed by scanning the output end of the optical fiber in two dimensions. A permanent magnet was attached to this end of the fiber, and it was displaced by a varying electromagnetic field. The device is computerized, which enables control of the scanning speed, laser output and magnetic field strength. Powered by a CO₂ laser, the equipment is capable of cutting, heating or marking various surfaces. This paper describes applications in which CO₂ laser energy is guided to remote locations via IR optical fiber. The output profile distribution, spot size and resolution were investigated and the results are compared to a simple theoretical model.

A theoretical ray model of IR radiation propagation and delivered beam shape profile of hollow flexible waveguides was developed. Experimental studies of attenuation of coupled CO₂ MID-IR laser (wavelength-10.6 micrometers ) and the influence of losses, internal diameter, coupling and scattering on the shape of propagated beam were performed. The theoretical and experimental results have shown a good concordance.

General chemical compositions of prepared glasses with low OH group concentrations are Ge_0.25Ga_0.10S_0.65, Ge_0.25Ga_0.05As_0.05S_0.65, (TeO₂)_x - (PbCl₂)_1-x with x equals 0.4 to 0.6 and (TeO₂)_x - (ZnO)_1-x with x equals 0.75 to 0.80. Samples doped with 500 to 12000 ppm rare earth in weight were prepared. Rare earth doped glasses are homogeneous when RE concentration is less than 3000 ppm. Heterogeneous inclusions arise beyond 1000 ppm RE when doping is made with chloride or oxide. Electron microscopy, absorption and fluorescence measurements have been made. YAG:Nd. Ar, He-Ne lasers were used for excitation of photoluminescence. The color and optic quality of the tellurite glasses depend on crucible materials. Rare earth doping results in visible defects or inhomogeneities when concentration is larger than 1000 ppm. The chemical composition and the optical absorption of doped and undoped samples was examined. Fluorescence intensity of Pr and Dy is smaller in these HMO glasses than in the sulfide glasses, which results from higher phonon energy and higher OH concentration. Further development is required for future applications.

The subject of the research was silicate glasses characterized by properly matched optical, thermal and rheological properties, which would enable their use in manufacturing of multifiber light and image-guide integrated rods aimed for high efficient guiding of VIS and NIR radiation (0, 4 divided by 2 micrometers ). Elaborating a synthesis and laboratory melting method of the low dispersion, high homogeneity colorless multicomponent silicate rod and clad glasses, mandatory components of fiberoptic light guides, as well as a high absorbing extra mural absorption glass, for outside optical insulation layer, has been presented. The manufacturing possibilities of integrated rod-shaped light and image-guiding structures, with high efficiency to transmit a VIS and NIR radiation have been stated. They are mainly used as light conductors in light-cured polymer dentist lamps, in laser devices for biostimulation, therapeutics, cosmetics, and medical treatments, as well as in advanced devices for photon coagulation.

To achieve efficient launching from the Er:YAG laser light to hollow fibers, we have developed a lensed-taper coupler, which is composed of a lens and a tapered hollow section with an inner coating of a cyclic olefin polymer and a silver. Transmission properties of the coupler have been experimentally investigated for the high-energy Er:YAG laser.

For screening applications in pharmaceutical research and in environmental analysis, homogeneous and heterogeneous phase assays are already well-established. The large number of samples to be examined requires the measurement of a multisample arrangement by means of parallel techniques which are improved by miniturization. This has the additional advantage of reducing the volume of samples and reagents, coming close to nanoliter volumes. For both approaches (high throughput screening and multisample detection in environmental analysis) imaging read-out systems are used which allow simultaneous monitoring of biomolecular interaction processes. Two applications are demonstrated: direct optical detection techniques of the affinity reaction between thrombin and inhibitors, as well as pesticide detection in environmental analysis using resonance energy transfer.

Human immunoglobulin G (IgG) and colostrum immunoglobulin A (IgA) were absorbed to hydrophobic silicon and the deposition of complement (C) was studied by ellipsometry- antibody techniques after incubation at 37 degree(s)C in human serum for up to 1 hour. In parallel experiments soluble iC3b, C4d and Bb were detected by ELISA-techniques. IgG coated surfaces rapidly activated the classical pathway and caused deposition of anti-C3c, antiproperdin, and during short serum incubation times also of anti-C1q and anti-IgG. The IgA-coated surfaces activated the alternative pathway and displayed a lag phase in the complement protein deposition. Anti-IgG, Clq, -C4, -factor H and -factor B were not deposited into IgA-surfaces at any time. Ellipsometry and antibody techniques offer a convenient and rapid means to display activation of the complement system by solid light-reflecting surfaces and facilitate a time-resolved determination of the activation pathway(s).

A surface plasmon resonance (SPR) apparatus was used to investigate blood plasma coagulation in real-time as a function of thromboplastin and heparin concentrations. The physical reason for the SPR signal observed is discussed and 3 different models are proposed. The response curves were analyzed by multivariable curve fitting followed by feature extraction. Interesting parameters of the sigmoid curves were lag time, slope and maximum response. When thromboplastin concentrations were increased, the lag-time decreased and the slope of the curve increased. A prolonged clotting time was followed mostly by increased maximum response, with exception for samples with no or very little thromboplastin added. High heparin concentrations changed the clotting kinetics. As seen from the lag-time vs. slope relation. Atomic force microscopy pictures of sensor surfaces dried after completed clotting, revealed differences in fibrin network structures as a function of thromboplastin concentration, and fiber thickness increased with lower thromboplastin concentration. The results correlate well with present common methods.

A fiberoptic system with a microstructure sensor element was used for measuring lumbar intervertebral disc pressure in a porcine model. The fiberoptic pressure sensor was inserted in the disc using a guiding needle. A reference sensor was also introduced into the same area of an adjacent disc. The fiberoptic sensor detected pressures from 0.7-8 bar in the disc. Dynamic measurements were carried out at frequencies between 2 and 10 Hz. No phase lag was observed between the applied force and the measured pressures. Sensitivity, dynamic response and available pressure range are all important design characteristics for which this fiberoptic sensor has a competitive edge.

We have investigated the possibilities of applying Raman spectroscopy for the in-vivo determination of blood glucose levels. To this end we measured Raman spectra of glucose dissolved in pure water and in the presence of other analytes such as glycogen and proteins. Secondly, we determined the fluorescence of blood serum for different excitation wavelengths. Since all measurements were done in an absolute way, we were able to predict if the Raman signal level of glucose was high enough to permit the in-vivo determination of the physiological glucose levels in blood.

Simultaneous measurements of the low frequency fluctuations of arterial blood pressure, heart rate, tissue blood content and tissue blood volume pulse were performed on 20 healthy male subjects. Arterial blood pressure was measured on the index finger by Finapres, simultaneously with photoplethysmography (PPG), which was measured on the other index finger. The changes in the PPG amplitude (AM), baseline (BL), and BV (defined by BV equals Const. - BL), are related to the changes in the tissue blood volume pulse (for AM) and the total tissue blood volume, (for BL and BV). The low frequency fluctuations of BV and AM were directly correlated, those of AM preceding those of BV by 4 - 13 heart beats. The low frequency fluctuations of SBP and DBP were inversely correlated to those of AM and BV. For most of the subjects P, which is the cardiac cycle period, was directly correlated with AM and BV. The interrelationship between the low frequency fluctuations in tissue blood volume, arterial blood pressure and heart period, provide us with a better understanding of the autonomic nervous control of the peripheral circulation.

Motion artefact corruption of pulse oximeter output, causing both measurement inaccuracies and false alarm conditions, is a primary restriction in the current clinical practice and future applications of this useful technique. Artefact reduction in photoplethysmography (PPG), and therefore by application in pulse oximetry, is demonstrated using a novel non-linear methodology recently proposed by the authors. The significance of these processed PPG signals for pulse oximetry measurement is discussed, with particular attention to the normalization inherent in the artefact reduction process. Quantitative experimental investigation of the performance of PPG artefact reduction is then utilized to evaluate this technology for application to pulse oximetry. While the successfully demonstrated reduction of severe artefacts may widen the applicability of all PPG technologies and decrease the occurrence of pulse oximeter false alarms, the observed reduction of slight artefacts suggests that many such effects may go unnoticed in clinical practice. The signal processing and output averaging used in most commercial oximeters can incorporate these artefact errors into the output, while masking the true PPG signal corruption. It is therefore suggested that PPG artefact reduction should be incorporated into conventional pulse oximetry measurement, even in the absence of end-user artefact problems.

Bile determination is very useful to diagnose many gastric pathologies. Actually, the measurement is performed with Bilitec 2000, an optical fiber sensor, based on the absorption of bilirubin. Nevertheless, erroneous evaluations can occur due to different configurations which the bilirubin molecule can adopt. The optical behavior of human samples of pure bile and bile + gastric juice has been examined by an optical fiber spectrophotometer and two properly modified Bilitec 2000 units. Analysis of pH dependance evidenced the presence of different calibration curves at different pH values, which Bilitec units showed that 420 nm could be a more appropriate wavelength for bilirubin detection.

The fitting of upper-extremity amputees requires special efforts, and its significance has been increased by the development of the myoelectrically controlled prosthetic arm. This solution is not free of problems due to the nature of the amputation, to the electromagnetic noise affecting the myelectrical signal and to the perspiration due to the contact between socket and the residual limb. Starting from the fact that NIRS and electromyographic signals are similar during a muscle contraction, we have first studied the NIRS signal during forearm muscle contractions in normal and amputee subjects. Then a new system to interface the NIRS unit and the myoelectrical prosthetic hand has been developed. The NIRS unit has been used as optical sensor and all the operations (I/O and signal processing) are performed via software. This system has been tested on normal and amputee subjects performing hand grasping using a visual biofeedback control scheme. All the subjects have been able to perform these operations demonstrating the NIRS technique. This could represent an alternative solution for controlling a prosthetic device.

A wireless noninvasive optical oxygen monitor based on near infrared spectroscopy is presented. Multiobjects (up to 20) could be monitored wirelessly by the center system. The monitor is made of two parts. Pare one is for the measurement of relative changes of oxyhemoglobin, deoxyhemoglobin, and total hemoglobin concentrations. The data from probe is transferred by RF. Part two includes hardware for data receiving, data preprocessing, A/D converting, communication with a portable computer, and software for real time data processing. Experimental results are demonstrated.

The exploitation of surface plasmon resonance optical sensor for the study of the interaction of immobilized fibrinogen and fibrin monomer with soluble fibrinogen and thrombin is reported. Soluble fibrinogen was mostly reversible, the bound thrombin could be inhibited by milimolar concentration of phenylmethylsulphonyl fluoride (PMSF). At lease three sets of different thrombin binding sites were found. There was a residual fraction of thrombin bound to washed fibrin (ogin) (to about a five to ten percent of fibron monomer units) suggesting that a known naturally occurring fibrinogen variant differing in the gamma chain was the target. Surface bound fibrinogen was converted by thrombin to fibrin monomer that interacted with fibrinogen in solution. At low fibrin monomer surface density the second layer was formed that contained about the same amount of protein as the first layer, at higher fibrin monomer concentration less than one molecule of fibrinogen per molecule of fibrin monomer was captured. Starting with surface-bound fibrinogen and alternating addition of thrombin and fibrinogen a fibrin network of predetermined composition, size, and arrangement could be formed.

A novel design of surface plasmon resonance fiber optic sensor is reported which leads to a compact, highly miniaturized sensing element with excellent sensitivity. The sensing device is based on a side-polished single-mode optical fiber with a thin metal overlayer supporting surface plasmon waves. The strength of interaction between a fiber mode and a surface plasmon wave depends strongly on the refractive index near the sensing surface. Therefore, refractive index changes associated with biospecific interaction between antibodies immobilized on the sensor and antigen molecules can be monitored by measuring light intensity variations. Detection of horse radish peroxidase (HRP) of the concentration of 100 ng/ml has been accomplished using the fiber optic sensor with a matrix of monoclonal antibodies against HRP immobilized on the sensor surface.

A NIR laser diode photoacoustic sensor is designed and used in tissue measurement. Laser diode is easy to carry out portable sensor. Because of low absorption of tissue in NIR region and the limited output power of the diode, the gain and SNR of the receiver should be high for measuring very low level signals. Developing higher pulse energy of laser diode and more sensitive transducer are the key for the diode sensor in application of biomedical measurement.

We study the influence of analytes on the scattering phase function of tissue mimicking phantom materials. These analytes change the scattering of the sample by a small fraction. We developed a system for measuring the scattering phase function of turbid media and used it to study the influence of analytes on the scattering phase function and the scattering cross section. Measurement of the scattering phase function of complex turbid media, such as human tissue mimicking phantoms, provides a means of increasing the accuracy of calculations of light scattering by such media. Instead of an assumed - generally simplified - phase function, one can use a more realistic phase function in e.g., Monte Carlo simulations. It also provides information on the scattering and absorption properties of the medium. The influence of analyte concentration is derived from changes in scattering, making it a relative measurement. This has the advantage that there is no need to determine the scattering itself. This paper discusses the experimental set-up and test measurements on monodisperse polystyrene latex suspension in comparison to Monte Carlo simulations, the possibility of extracting the scattering phase function. We also present measurements of the influence of an analyte on the scattering properties of biological tissue in vitro. The change in scattering coefficient found from these measurements is in good agreement with theoretically predicted values.

A reflectance-type photoplethysmographic sensor probe connected to personal computer has been constructed and tested. Special algorithms and PC programs providing fast processing and smoothing of the output signals were developed. High-quality single period photoplethysmography signals were recorded from various locations of the body (fingers, forearm, neck). Clear differences in the shapes of detected single-period signals have been observed for different persons, and also for the same person at various measurement locations and before/after physical exercise.

The large quadratic electro-optic effect of PLZT ceramics allows to design small size modulators for the solid state infrared Er:YAG laser (lasing at (lambda) equals 2.94 micrometers - the most pronounced absorption band of water), which has found application in medicine for efficient ablation of hard and soft tissues. In the free-running mode, the Er:YAG laser emits spikes that form the pulse envelope with duration of 150 - 800 microsecond(s) . An extracavity PLZT 8.5/65/35 ceramics modulator (aperture of 4 X 6 mm² and length of 18 mm) was used to obtain (Pi) -shaped segments with the rise and decay times less than 5 microsecond(s) . That allows to reduce considerably the fraction of the pulse energy below the ablation threshold so avoiding undesirable heating of tissues. The halfwave voltage of such modulator was 1350 V with an additional DC bias of 300V. The contrast ration K > 15:1. The Q-switching technique was applied to obtain high intensity small duration monopulses using modulators of the same PLZT 8.5/65/35 ceramics. PLZT ceramics Q-switches (tested in two schemes - as a (lambda) /4 switch placed perpendicular to the beam with a length of 6mm without antireflection coatings; and as a (lambda) /2 switch with a length of 3 mm placed at the Brewster angle) allowed to obtain monopulses with the energy of 5 - 8 mJ and with a pulse width of 150 ns.

We report on the design and fabrication of a low Reynolds number silicon/pyrex microfluidic device that forces particles flowing in a microchannel to a tightly-focused equilibrium position. This device can be used for optical biomedical systems such as a flow cytometer so that particles can flow in a precise position without sheath flow for precision scattering or fluorescence measurements. Devices with a range of dimensions were fabricated using photolithography and wet chemical etching techniques. Particle positions in the channel are determined by observing the direct image as well as two reflection images from the sloping, polished channel walls. We tested devices with various ratios of width to particle diameter at a range of flow rates. When scattering signals from 10 micrometers polymer beads are measured, we observe that the tight equilibrium position attained by the particles results in a much smaller standard deviation of the scattering signal than is observed in other microflow channel devices that do not focus the particles to equilibrium positions.

The biofeedback control analysis of human movement has become increasingly important in rehabilitation, sports medicine and physical fitness. In this study, a synchronized system was developed for acquiring sequential data of a person's movement. The setup employs a video recorder system linked with two CCD video cameras and fore-plate sensor system, which are configured to stop and start simultaneously. The feedback control movement of postural stability was selected as a subject for analysis. The person's center of body gravity (COG) was calculated by measured 3-D coordinates of major joints using videometry with bundle adjustment and self-calibration. The raw serial data of COG and foot pressure by measured force plate sensor are difficult to analyze directly because of their complex fluctuations. Utilizing auto regressive modeling, the power spectrum and the impulse response of movement factors, enable analysis of their dynamic relations. This new biomedical engineering approach provides efficient information for medical evaluation of a person's stability.

In view of future generations of biosensors, immobilization of biomolecules with high spatial resolution onto selected materials or transducer surfaces is required. One way to attach the biomolecules is to induce covalent bonds with the substrate using a photochemical effect. High localization in the attachment is obtained when performing the photochemistry in the next field. In this paper, we present patterns of covalently bond proteins, written with near field UV activation. Observation is done in the near field as well, using near field fluorescence microscopy.

Multispectral imaging autofluorescence microscopy (MIAM) is used here for the analysis of lymphatic tissues. Lymph node biopsies, from patients with lympthoadenopathy of different origin have been examined. Natural fluorescence (NF) images of 3 micrometers sections were obtained using three filters peaked at 450, 550 and 680 nm with 50 nm bandpass. Monochrome images were combined together in a single RGB image. NF images of lymph node tissue sections show intense blue-green fluorescence of the connective stroma. Normal tissue shows follicles with faintly fluorescent lymphocytes, as expected fro the morphologic and functional characteristics of these cells. Other more fluorescent cells (e.g., plasma cells and macrophages) are evidenced. Intense green fluorescence if localized in the inner wall of the vessels. Tissues coming from patients affected by Hodgkin's lymphoma show spread fluorescence due to connective infiltration and no evidence of follicle organization. Brightly fluorescent large cells, presumably Hodgkin cells, are also observed. These results indicate that MIAM can discriminate between normal and pathological tissues on the basis of their natural fluorescence pattern, and, therefore, represent a potentially useful technique for diagnostic applications. Analysis of the fluorescence spectra of both normal and malignant lymphoid tissues resulted much less discriminatory than MIAM.

Fluorescence lifetime-based sensors are well-suited for chemical and biological applications since they are relatively insensitive to background light intensity, fluctuations and bleaching of fluorophores. Examples of applications include biosensing strategies where binding or a target analyte to an immobilized biological receptor molecule results in a change in the fluorescence lifetime of a fluorescent reporter group. It is desirable in many instances to have a sensor array to monitor the simultaneous binding of several analytes. We have designed a multichannel system using LEDs (or laser diodes) to excite fluorescence, multiple photodetectors, and a multichannel computer algorithm-based phase meter. The multichannel phase meter utilizes a PC and multichannel digital acquisition board. The resolution of each channel in the multichannel phase meter has been estimated at approximately 0.05 degrees. The eigen-phase fluctuations for each channel of the system are approximately 0.15 degrees, which allow us to estimate the lifetime resolution as better than 10 ps. We estimate the processing time of phase measurements for each channel as less than 200 ms. The usefulness of the system has been demonstrated in several operational examples, including a multichannnel pH meter and a fluoresphore competitive immunoassay-based chemical sensor.

In this work authors describe a new scanning laser ophthalmoscope (SLO) device, which allows the separation of the apparatus into two parts: one near the hear of the subject, the other far from the subject. A fiber optic double pass illumination/detection technique is used. Reflections coming from fiber facets are eliminated by: polarization, time-gated illumination/detection techniques and 8^DGR angled facet. The SNR measured is 40. This device improves by 2 times the retina luminous level to noise luminous level ratio in comparison to conventional SLO. Double pass fiber optic SLO allows eye environment miniaturization, removes sources and detection devices far from patient, and improves image contrast.

Trace mineral analysis of the body is invaluable in biology, medicine and dentistry when considering the role of mineral nutrition and metabolism in the context of maintaining human health. The presence of key elements in the body, such as boron, calcium, chromium, copper, iron, silicon and zinc are known to be of vital importance, but are often found to be present in inadequate quantity. In sharp contrast, the accumulation of other elements, such as aluminum, cadmium, lead and mercury is less favorable, since frequently these metals are already toxic at extremely low concentration levels, interfering with essential chemical processing of vitamins and minerals. Here we report on the application of laser-induced breakdown spectroscopy and laser-induced fluorescence spectroscopy to the analysis of important minerals and toxic elements within the body. Samples from different parts of the body have been studied, including specimens of skin tissue, finger nails and teeth. It is particularly noteworthy that specific sample preparation was not needed for any of these laser spectroscopic measurements, but that specimens could be used as taken from the source.

Time-resolved measurements of femtosecond light pulses transmitted through turbid biological media were performed to determine the optical absorption and scattering coefficients. A simple model based on the time-dependent diffusion equation allows us to calculate analytical expressions for the spatially-integrated time-resolved transmittance in terms of the interaction coefficients of the tissue slab. We derived the optical coefficients by fitting the diffusion solution to the experimental data of the spatially integrated time-resolved diffuse transmittance for different boundary conditions at the turbid medium-air interface.

Pioneer Hi-Bred is developing a low-cost method for rapid screening of DNA, for use in research on elite crop seed genetics. Unamplified genomic DNA with the requisite base sequence is simultaneously labeled by two different colored fluorescent probes, which hybridize near the selected gene. Dual-channel single molecule detection (SMD) within a flow cell, then provides a sensitive and specific assay for the gene. The technique has been demonstrated using frequency- doubled Nd:YAG laser excitation of two visible-wavelength dyes. A prototype instrument employing infrared fluorophores and laser diodes for excitation has been developed. Here, we report results from a Monte Carlo simulation of the new instrument, in which experimentally determined photophysical parameters for candidate infrared dyes are used for parametric studies of experimental operating conditions. Fluorophore photostability is found to be a key factor in determining the instrument sensitivity. Most infrared dyes have poor photostability, resulting in inefficient SMD. However, the normalized cross-correlation function of the photon signals from each of the two channels can still yield a discernable peak, provided that the concentration of dual- labeled molecules is sufficiently high. Further, for low concentrations, processing of the two photon streams with Gaussian -weighted sliding sum digital filters and selection of simultaneously occurring peaks can also provide a sensitive indicator of the presence of dual-labeled molecules, although accidental coincidences must be considered in the interpretation of results.

A transmittance pulse oximeter based on near-infrared laser diodes for monitoring arterial blood hemoglobin oxygen saturation has been developed and tested. The measurement system consists of the optical sensor, sensor electronics, acquisition board and personal computer. The system has been tested in a two-part experimental study involving human volunteers. A calibration curve was derived and healthy volunteers were monitored under normal and apnea conditions, both with the proposed system and with a commercial pulse oximeter. The obtained results demonstrate the feasibility of using a sensor with laser diodes emitting at specific near-infrared wavelengths for pulse oximetry.

This paper describes an enhanced noninvasive continuous laser Doppler system for real time blood flow measurement in perfusion regions and larger vessels. The system consists of a miniaturized sensor, a fast digital signal processing (DSP) unit and a PC for signal visualization. The sensor comprises an IR laser diode to illuminate tissue through a short optical fiber with a variable spot size of 400 micrometers to 1000 micrometers and a photodetector which can be positioned 3 mm to 7 mm from the laser spot. The DSP of the system uses a parametric estimation of the laser Doppler power spectrum density based on a first order autoregressive process model AR (1) to calculate the first weighted moment. This algorithm is approximately ten times faster and as accurate as equivalent FFT-based algorithms. With a sampling rate of 390 kHz, it is possible to calculate and visualize 85 flow values per second. Model measurements prove very high linear correlations (r >= 0.99) between calculated first moments and flow velocities in a range from 1 mm/s up to 120 mm/s. Furthermore, in vivo measurement of blood flow both in perfusion regions and larger arteries, such as the a. radialis, were successfully performed in real time.

Silver halide IR-transmitting fibers were coated with polymer films in order to protect them from deterioration caused by interaction with biological fluids. Such coated fibers can be used for human blood serum analysis carried out the fiberoptic evanescent wave spectroscopy (FEWS) using a Fourier transform infrared spectrometer. A dip-coating procedure was worked out for coating fibers with polystyrene or silicone-elastomer thin films. Deterioration tests of coated fibers in saline solution which imitates human blood serum salts were performed. These demonstrated that the polymer layers provide protection to the fibers, while making it possible to carry out FEWS measurements.