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Dialysis treatment poses the risk of cardiovascular problems. Non-invasive blood pressure measurement based on the Riva-Rocci method (gold standard) is used to detect a drop in blood pressure at an early stage. Frequent non-invasive blood pressure measurements are both disturbing and painful for the patient and thus often rejected. It is suspected that a change in pulse wave velocity or pulse transit time can indicate a change in blood pressure and circulatory function. It is being investigated whether continuous pulse transit time measurements can serve as a trigger for less frequent non-invasive blood pressure measurement. A custom built measurement system is presented and used to measure the pulse transit time during a case study. Our results indicate a potential use case for the pulse transit time as a trigger for cuff based blood pressure measurements.

The measurements of electrocardiographic and plethysmographic signals are two of the standard measurement techniques which are performed as noninvasive spot check methods of human health condition in hospitals, home-care or other health care facilities. Therefore, specialised electronic systems exist, which perform either of the two measurements. For the separate analysis of one signal at a time this is a sufficient approach, but if the correlation of the two signals is of particular interest it might be better to combine the measurement systems into one system as a signal delay between the different measurements is avoided. This paper aims to describe a specialised hardware frontend, which is capable of high speed, high precision, concurrent and time synchronised recording of the electrocardiographic and plethysmographic signals. It makes it possible to correlate both signals and to generate new data such as the pulse transit time. This parameter is presumed to be a marker of blood pressure or stress and is therefore of high interest of being investigated.

This paper compares the data of five acceleration sensors of three different types at two different placements on a dairy cow. Data was collected in video surveilled measurement series. The studies are targeting the development of an activity monitoring system integrated in a collar. The acceleration data of the sensors was analyzed regarding the standing-up, lying-down and rumination event. An acceleration sensor was chosen for further development of the event recognition with machine learning algorithms.

The method, data analysis, selection and use of different classifiers with the corresponding detection rates for the evaluation of data of an acceleration sensor on the collar on dairy cows for detecting standing-up and laying-down are presented in this paper. Data was collected in video surveilled measurement series. The studies are targeting the development of an activity monitoring system integrated in a collar without an additional ankle monitor. This paper will investigate the development of classifier by using different machine-learning techniques, the "coarse tree" combined with saviztzky-golay differentiation and a neural net with backpropagation algorithm. At the end the results of the methods used are presented and compared.

A low cost and compact sensor system for mobile measurements of combustion gases is described. The sensor utilizes optical absorptions in the UV-Vis range using LED-based spectroscopy. Combustion processes are currently one major cornerstone in the way we are using primary energy sources in our modern life. Harmful gases such as nitrogen oxides (NO x ) and sulfur dioxide (SO 2 ) as well as particles are emitted thereby in significant amounts if the processes, engines, catalysts and filters are not working properly. It is important to enable an easy to use and low cost monitoring of these harmful emissions: Applications are spot check emission control in transport, in industry, in harbor areas or mobile functionality control in operation of combustion devices and industrial gas filters. A cost effective mobile sensor is realized for the measurement of NO 2 and SO 2 in wide dynamic range from 0.1 ppm to a few 1000 ppm with high temporal dynamic (100 msec). Further an opacimeter measurement and a stray light sensor for particle detection are included. In addition temperature, humidity and pressure are measured. The presented sensor design is optimized for mobile airborne gas measurements. Its construction is adapted to a license free commercial 1400 g video drone. The sensor is simply clicked under the drone, while the drone functionalities (video, distance sensors etc.) are not influenced by the gas sensor. The sensors weight is about 300 g including its battery. The measurement data are recorded on SD-card and are send for online visualization via Bluetooth e.g. to a smartphone. The light weight, compact, robust and low power consuming battery powered sensor design can also be used in hand held devices. In addition the sensor can easily be modified for other gases such as for ozone (O 3 ) detection.

The measurement of carbon dioxide in medical application is well established for a long time. Medical key parameters such as the end tidal CO 2 concentration are well known and very useful in day-to-day clinical work. It is a non-invasive method for monitoring the patient's pulmonary function in emergency or intensive care as well as in anesthesia. The combination of a respiratory CO 2 -measurement with a volumetric breathing measurement enables the detection of the minute volume of CO 2 . This is an important parameter in respiratory medicine. The combination with an additional respiratory oxygen measurement is used for indirect calorimetry and enables the characterization of the metabolism. Such measurement methods are used in a wide range of applications, for instance in medicine, home car as well as in sports medicine. Although capnometers are state of the art for a long time and well developed, this paper shows a new design approach to improve sensor parameters such as power consumption, start-up-time, measurement time and robustness. Prototype sensors are realized for main- and side-stream application. CO 2 -measurements of the newly developed sensors are presented in comparison with results of commercial devices.

A cost effective and compact sensor system is described that provides an online measurement of combustion gases. Based on UV-VIS-absorption spectroscopy the most important hazardous emission gases nitrogen oxide (NO), nitrogen dioxide (NO 2 ) and sulfur dioxide (SO 2 ) are measured individually and quasi simultaneous with high temporal resolution. A demonstrator device was set up that utilizes only one measurement chamber so the detection of all gases takes place in the same measurement volume. The demonstrator shows a wide concentration dynamic range of some 1000 ppm and a resolution of below 1 ppm for all three gases. Such a sensor system can be used for online emission monitoring of combustion engines in transportation area as well as in stationary industry application. Especially because of the selective detection of the critical emission gas components NO and NO 2 the system can also be used for a well-directed engine and after treatment system control to optimize the catalyzers reactions to efficiently reduce harmful emissions of combustion engines.

The lifetime of modulated incandescent lamps depends on modulation parameters like frequency, amplitude and the type of modulation. In contrast to well-known methods of DC lifetime estimation, this paper describes the lifetime estimation of modulated small sized tungsten incandescent lamps. For that purpose the approved procedure of material evaporation was compared with a method based on electrical lamp data only. They both were specified for DC operation, so the most suitable procedure was chosen and adapted for lifetime estimation at modulated operating points. To verify this procedure, lamps were tested at different modulated points of operation. A comparison of measured and estimated lifetime shows, that the new procedure is suitable to estimate the lifetime sufficiently. This method does not require any knowledge of geometrical lamp parameters like filament's dimensions. It is based on time dependent voltage and current data which can be measured easily and it forms an adequate method for lifetime estimation of incandescent lamps, applicable for different types of modulation.

The paper describes the evaluation of captured 3D-acceleration data from collars of dairy cows regarding the prediction of the state of health. It focuses as a first step on the distinction of laying and standing activities and develops a classifier for a target system with restricted memory and CPU-resources. Therefore, a two-step classification algorithm is developed so that a deployment of resource-intensive task to a backend system is possible. A data reduction is considered to minimize data-transmissions and power consumption. The developed algorithm reaches data reduction on the embedded system to at least 2.6 % and an accuracy up to 90 % for the distinction of laying and standing activities.

A mode filter for LED-based gas absorption spectroscopy is shown. Two LEDs with different wavelengths are used for the measurement of gas concentrations. One wavelength for measurement and a second wavelength as reference. This allows to measure gases like NO2 (405nm) and SO2 (285nm). Different disturbances, like temperature, vibrations and the optical properties of LEDs require a mode filter to reduce their influences. The mode filter is eight-shaped. It is examined, how many windings on the mode filter are required to suppress the influence of disturbances. Three kinds of disturbances were evaluated: bending a fibre, shifting a fibre connector and changing the temperature of a fibre connector. An improvement with the mode filter is determined for different number of windings. For more than 7…8 windings on the mode filter, there is no significant improvement. Only the losses of the fibre system increase with an increasing number of windings. Mode filters are indispensable for a high sensitive sensor system.

Using more and more sensors, an increase in complexity and quantity of wiring is the consequence. This can be solved by using wireless sensors which are powered by energy harvesting. For this purpose, thermal energy harvesting by using atmospheric temperature variations is investigated by using a test setup in a climate cabin with a 65 minutes temperature cycle with minimum temperature of −40°C for 6 minutes. The results shown a maximum reached temperature difference is 37.5 K which results in 6 mW electrical power the chosen thermos-electric generator (TEG) produces. Utilizing an energy-harvesting power management unit to the setup results in a maximum electrical energy conversion efficiency of 92% and a maximum electrical storage power in a supercapacitor of 5.5 mW. The overall electrical energy the TEG generates is 8.85 J. The total energy that is stored in the supercapacitor is 7.85 J, which is an overall energy conversion efficiency of 89%. The results of using two identical TEGs parallel in the same thermic setup shows the limitation of this.

Real time, high resolution measurements of gas concentrations are a task in many industrial applications like smoke detectors, medical and analytical devices. By usage of LED sources for optical absorption spectroscopy, such systems have a high potential to replace commonly used electrochemical sensors, even in low-cost applications. Depending on the gases, they can provide higher sensitivity, selectivity and dynamical response. Background of this paper is the optical gas concentration measurement by usage of LEDs, which are matching the specific absorption lines of different gases. The paper describes in detail a laboratory device, developed for high precision, multispectral (up to 8 wavelengths), referenced (20-bit, two-channel simultaneous sampling) measurement system with temperature stabilized LED sources. While the described system was developed for laboratory purposes with high precision and flexibility in mind, the key components (ADC / LED-Driver) are very low-cost and the system could also be driven by a simple microcontroller.

A real time, high resolution LED based, spectroscopic gas concentration measurement system is presented. This kind of measuring techniques was enabled by the advances in the fabrication of ultraviolet LEDs (UV-LEDs). The system presented here has a relatively compact design and small application efforts. Different hardware setups have been evaluated to design a system for real time high resolution LED absorption spectroscopy. Applied are two concave mirrors, two photo detector diodes and a 405nm LED mounted in a small device. A standard low power microcontroller was applied as signal processor. The few, robust, reasonable priced components enables high volume applications for this sensor. Different optical simulations provide optimized system parameters for gas concentration measurements in the low ppm range. NO2 concentrations of 200 ppm have been measured with a resolution of ∼1.5% counts (16-Bit-ADC). Therefore the ppb range becomes an available measurement range with higher ADC-Resolutions.

Today, digital micromirror devices (DMD) are mainly used for multimedia applications like image or video projection and in some cases for structured light measurements. But like most optical devices, DMDs can also be used in the opposite direction to collect the light from an object instead of illuminating it. This paper shows the potential of DMDs for velocity and path measurement applications based on the well known spatial filter technique. Used as a spatial filter, the DMD combines the advantages of a fixed grid (fast, high dynamic range) with the flexibility of structured receivers like CCD- or CMOS-Matrix sensors.

In many industrial applications different sensors (magnetic, acoustic, optical) have to work under rough conditions. Smart sensors with integrated signal conditioning and processing avoid cable influences and are capable to reject further disturbance influences by signal processing of multi parameter measurements. This article describes a low-power interface for two-wire sensors. The sensor interface was developed for an intelligent eddy current sensor but the concept is not restricted to inductive sensors only.

Reliable online sensor measurement data are the foundation of autonomous controlled processes. One important issue for a high quality production (closed loop control) as well as for environmental protection (waste reduction, reduction of harmful exhausts) is the in-situ concentration measurement of substances. Especially the selective and high resolved detection of individual substances is a complex issue for low cost sensor solutions. Optical spectroscopy is a valuable method according the selectivity and resolution but appropriate setups are quite complex (e.g. specialized light sources, spectral filtering optics, mechanical accuracy) thus they are cost intensive and almost not autonomous. This paper presents a low cost and high resolution (ppm and ppb range) spectrometric sensor system for gas detection in harsh environment. New LEDs are utilized as wavelength selective light sources in combination with standard photodiodes and optical fibers to realize robust in-situ gas measurements. Referenced measurement results for different applications are shown and discussed.

One of the main reasons for revision of total hip replacements (THR) is the aseptic or septic loosening. The Osseointegration of the uncemented hip stem in the femoral bone has to detect exactly in order to enable early state loosening detection. All present diagnostic methods, e.g. radiographs and arthroscopy, show insufficient sensitivities and specificities between 70% and 80%. Osseointegration can be identified in-vivo by use of acoustic methods. The acoustic waves can be generated by a mechanical hammer or by a piezoelectric transducer placed on the inside the femoral hip stem wall. Thereby the mechanical-acoustic properties of the bone interface give information about the status of the loosening process.A functional model of the measuring principle shows significant differences in varied phases of fixation. The new acoustic sensor system demonstrates its potential to detect aseptic loosening. Moreover, the proposed system could be used in experimental applications to determine the quality of osseo-integrative coatings and new implant materials as well.

Approximately 200,000 patients are treated with total hip replacements (THR) in the United States per annum, in European Countries over 500.000. The main reason for revision of total hip replacements (THR) is the aseptic or septic loosening. The Osseointegration of the uncemented hip stem in the femoral bone has to be detected exactly, in order to enable early state loosening detection. All present diagnostic methods, e.g. radiographs and arthroscopy, show insufficient sensitivities and specificities between 70% and 80%. Osseointegration can be identified in-vivo by use of ‘active’ acoustic methods. The acoustic waves can be generated, e.g. by a mechanical hammer placed on the inside of the femoral hip stem wall. The mechanical-acoustic properties of the bone-implant interface give information about the status of the loosening process. A functional in-vitro model of the measuring principle shows significant differences in varied phases of fixation. The new acoustic sensor system demonstrates its potential to detect aseptic loosening.

Non-invasive continuous real-time assessment of patient conditions for the diagnostic purposes is a target of the state-of-the-art clinical monitoring technology. Such a surveillance system for the peripheral vascular diagnostics was designed during current research by combining the pulse spectroscopy and advanced signal processing. Analysis of the rhythmic activities in blood circulation reveals a state of the cardiovascular control mechanisms. Considering that the photo-plethysmographic (PPG) waveform is a pressure-induced signal, the correlation between the pulse features with pressure-resistance characteristics of the vessels was derived. By means of the pulse-contour-analysis (PCA) specific amplitudes, systolic slope, dicrotic transit time etc. can be extracted. It was found that the power spectra of the wavelet spectrograms expose significant diagnostic information about the cardiovascular control mechanisms of the microcirculation.

NIR-spectroscopy and Photoplethysmography (PPG) is used for a measurement of blood components. The absorption-coefficient of blood differs at different wavelengths. This fact is used to calculate the optical absorbability characteristics of blood which is yielding information about blood components like hemoglobin (Hb) and arterial oxygen saturation (SpO 2 ). The measured PPG time signals and the ratio between the peak to peak pulse amplitudes are used for a calculation of these parameters. The newly developed optical sensor systems use up to five wavelengths in the range of 600nm to 1400nm for a measurement of the hemoglobin concentration, oxygen saturation and pulse. This noninvasive multi-spectral measurement method was tested with prototype-devices based on radiation of monochromatic light emitted by laser diodes and by using light emitting diodes (LED) through an area of skin on the finger. The sensors assembled in this investigation are fully integrated into wearable finger clips.

The spectroscopic optical absorption technique is widely used for estimation of substance concentration. It is based on the wavelength specific determination of light extinction in an absorption cell that is caused by the interaction of light with the molecules of the claimed substance. The absorption measurement is an indirect method because a light attenuation (often only at a few spectral measurement points) is used. This measurement is not only influenced by the substance absorption but also unwanted by disturbances and changes of light emission, guiding and receiving. New optical methods for realizing an online reference for a robust absorption measurement has been designed and investigated. Compared to commonly used methods the designed technique is not complex but effective and also well suited for small sensor application. The utilized concept is based on the variation of the effective absorption path length within a sensor cell in a simple way. Stable absorption measurements at the presence of strong spectral changes of the light source intensity are shown here to demonstrate the potential of the developed technique.

Photoplethysmographic (PPG) signals reflect the regulations of heart rate, blood and stroke volume and peripheral resistance of blood vessels. The technique of Continuous Wavelet Transformation (CWT) is applied to the irregular and weak PPG signals. The CWT of the PPG data is found to be a specific, sensitive, nonlinear method for the in vivo identification of hearth circulation patterns. The disadvantage of the traditionally used STFT is that this technique averages short-duration components and cannot capture those components that last longer than the window itself. This problem was solved by using the CWT. With our approach a monitoring of diabetic microangiopathy status, compensation the blood pressure drop during dialysis sessions by vascular vasoconstriction and the linkage between abnormal hemodynamic parameters and PPG-pulse features where observed and should be further quantified in order to deliver parametric diagnostic data for the medical personal.

The ability to monitor environmental conditions is crucial to research in fields ranging from climate variability to agriculture and zoology. Being able to document baseline and changing environmental parameters over time is increasingly essential important and researchers are relying more and more on unattended weather stations for this propose. A Zigbee Based Smart Sensing Platform for Monitoring Environmental Parameters has been designed and developed. The smart weather station consists of SiLab C8051F020 microcontroller based measuring units which collect the value of the temperature, relative humidity, pressure and sunlight. These units send their data wireless to a central station, which collects the data, stores and displays them into a database. The facility of adding a few more sensors and a few more stations has been provided.

This paper deals with the optimization of a customary inductive proximity sensor. The focus in this paper lays on the significance of the side-metal-effect in magnetic sensors, which has remarkable influence on the accuracy of these sensors and has to be investigated for specific sensor configurations. Furthermore, solutions and strategies for reducing the side metal effect are explained and evaluated.

A novel motion-tolerant algorithm for continuous real-time monitoring of blood constituents by means of pulse oximetry is introduced. Motion artifacts frequently lead to false interpretations of the measured signal or can cause a failure of the signal detection. Therefore these disturbances are required to be recognized and suppressed while the useful signal should remain possibly unaffected. The technique is based on the continuous wavelet analysis combined with optional adaptive peak filtering to optimally estimate the physiological parameters. Presented algorithm appears to be a sensitive nonlinear method of processing the pulsative arrhythmic patterns in frequency domain. Reconstruction of the motion-corrupted PPG-waveform could allow an elicitation of the individual clinical parameters which yield additional data about the human health status. The method is not limited to non-invasive oximetry only and can be utilized in other medical fields of patient monitoring.

Noninvasive continuous patient monitoring in real-time is considered to be the “Holy Grail” of hemodynamic assessment. Early detection of the changes in circulatory parameters prevents potential deseases, organ failures and death. For the purposes of the clinical patient surveillance this goal can be attained by enhancing of the pulse waveform analysis. Pulse oximetry is an established method for the noninvasive measurement of arterial blood saturation and pulse rate. With advances in digital signal processing its range can be expanded for the acquisition of extra diagnostic data. Software algorithms were tested on 46 patients in the dialysis station and intensive care unit (ICU). Continuous wavelet transform (CWT) was used as a tool for complete monitoring of the microdynamics at the sensor site. Spectrum of the microregulatory mechanisms can be represented in 3D-time window by means of the frequency allocation. Wavelet transforms applied to the pulse oximetry signals reveal a great potential for analysis of the cardiovasculatory processes in clinical environment.

Metal detectors (MD), based on the eddy current principle, are widely-used in humanitarian demining. The sensor signal (i.e. the induced complex coil voltage) is influenced by the object properties (material, shape). This effect was used in previous research projects to classify suspicious objects. But the identification of multi-target situations (a mine covered by a neighboring metal object) was still unsolved. From a 2D raw data image only shapes larger than the coil diameter can be visualized. In this paper the deconvolution of multivariate spatial referenced MD-data is used for imaging object distributions, shapes and material properties. The key to a high resolution image reconstruction is the reduction of disturbance influences caused by soils with magnetic properties. The ability to identify multi-target situations and recognize mines by their characteristic metal distribution was demonstrated on test lanes for mine detection provided by the University of Rostock and the CTRO-Benkovac.

The left-ventricular stroke volume is an important direct indicator of the heart efficiency and perfusion of the vessels. Currently a valid measurement of the beat volume can only be implemented by invasive measurements procedures at the hospitals worldwide. Arterial catheterization is limited to intensive care unit (ICU) usage, costly and potential risky. Some available noninvasive methods yield rather an ability to track relative changes. Values delivered by these techniques are highly subjective and controversial. Enhanced pulse spectroscopy and advances in digital signal processing allow reliable measurement of the changes in peripheral blood volume with subsequent estimation of the cardiac output (CO). The aim of the current work was to design a continuous nonivasive system for the absolute monitoring of the heart beat volume (HBV). And eventually prove the validity of this new method by comparing with the standard invasive technique. It was a first trial to achieve a noninvasive measurement of the HBV by the instrumentality of a standard pulse oximeter, advanced signal processing algorithm and single individual calibration. Software algorithm has been tested on ten patients with various disorders of the cardiovascular system. The real-time absolute references of the HBV were obtained via PiCCO catheterization system (Pulsion Medical Systems, Munich, Germany) on the femoral arteries for three patients. Technology presented in this paper faces clinical needs in intensive care unit, internal medicine unit, operative, postoperative and patient recovery areas. The medical relevance of these devices is high.

The Hemoglobin (Hb) concentration in human blood is an important parameter to evaluate the physiological condition. A hemoglobin test reveals how much hemoglobin is to be found in the blood. With this information anemia (a low hemoglobin level) and polycythemia vera (a high hemoglobin level) can be a diagnosed and monitored. It is also possible to observe postoperative bleedings and autologous retransfusions. Currently, invasive methods are used to measure the Hb concentration. For this purpose blood is taken and analyzed. The disadvantage of this method is the delay between the blood collection and its analysis, which does not allow real-time monitoring of patients in critical situations. The non-invasive method, discussed in this paper, allows pain free online monitoring of patients with minimum risk of infection. Real-time data monitoring facilitates immediate clinical reaction to the measured data.

The usage of novel LED-light sources for spectrometric application is shown and described in this paper. The utilization of fiber optical linkage to a simple open path absorption cell and a proper control of the light sources is the key to a robust and high resolved measurement system. A novel optical sensor system based on this approach is realized to measure the concentration of nitrogen dioxide, sulfur dioxide with a resolution below 1 ppm and ozone down to 30 ppb at a 4 cm single reflection cell in a fraction of a second measurement time. In this setup the emitted light from Light Emitting Diodes in the ultraviolet to the visible wavelength range was used. The optoelectronics and the control electronics are separated from the optical sensor head where the pure optical sensor effect takes place. Therefore the sensor can be used in harsh environment for instance in an exhaust tailpipe system or close to discharge plasma in strong electromagnetic fields or at high temperature. Furthermore the sensor design is potentially low cost, quite small, long life and well suited for a large number of applications - from small battery powered hand held devices to industrial process control implementation. An LED-based sensor does not compete to laboratory chemical analytical devices but in many cases it is well suited for high resolved and fast online concentration measurements.

The sensitivity of inductive proximity sensors decreases exponential with increasing distance of the target to the sensing element. The temperature effect and cable influence dominates the measured impedance at the end of the sensing range. For precise measurements, also under a wide specified range of temperature and cable length, disturbance influences must be rejected. Therefore methods, known from the field of non destructive testing and metal detection can be adapted. If the sensing range is defined by a maximal tolerated deviation, a better disturbance rejection leads to a higher range for the proximity sensor.

A realized novel optical sensor system to measure the concentration of ozone using the emitted light from Light Emitting Diodes in the ultraviolet range is described in this paper. The wavelength selective light interaction of the gas takes place in a fiber coupled and robust reflection cell. The control electronics are separated from the optical sensor head. Therefore it can be used in harsh environment for instance close to discharge plasma in strong electromagnetic fields or at high temperature. The sensor design is potentially low cost, quite small and well suited for a large number of applications. It can be implemented in industrial process control application or in small battery powered hand held devices. This setup is also capable for a parallel and selective measurement of nitrogen dioxide NO 2 and sulfur dioxide SO 2 - this is already implemented and proved. Further specific LEDs are utilized for this purpose in the setup. For the ozone measurements two different sensor heads where used. A small 4 cm long reflection cell with potential for handheld devices and a 40 cm one thought for high resolution stationary application. The resolution (standard deviation measured at a zero concentration of ozone) of the sensor with the small cell is about 30 ppb at 700 msec measurement time and about 3 ppb at 1,4 sec at the longer cell.

Metal detectors based on the eddy current principle are widely used in humanitarian demining, but their main disadvantage is the high false alarm rate caused by harmless clutter objects or “uncooperative” soils. In most cases, the types of mines in the field are known a-priori. So their influence on the metal detector can be measured and stored in a database. In this paper a new method is described that uses this information to adapt the soil compensation and the signal classification to achieve a significant reduction of false alarms. Therefore a fuzzy classifier is used that adapt to the signal quality and feature variance of the known objects. The ability to lower the false alarm rate was verified by trials on the test lane for mine detection provided by the Joint Research Center in Ispra (Italy).

The Hemoglobin (Hb) concentration in human blood is an important parameter to evaluate the physiological condition. A hemoglobin test reveals how much hemoglobin can be found in the blood. With this information anemia (a low hemoglobin level) and polycythemia vera (a high hemoglobin level) can be a diagnosed and monitored. It is also possible to observe imminent postoperative bleedings and autologous retransfusions. Currently, invasive methods are used to measure the Hb concentration. For this purpose blood is taken and analyzed. The disadvantage of this method is the delay between the blood collection and its analysis, which does not allow a real-time patient monitoring in critical situations. A non-invasive method allows pain free online patient monitoring with minimum risk of infection and facilitates real time data monitoring allowing immediate clinical reaction to the measured data.

In the perioperative area, the period before and after surgery, it is essential to measure diagnostic parameters such as oxygen saturation, hemoglobin (Hb) concentration and pulse. The Hb concentration in human blood is an important parameter to evaluate the physiological condition. By determining the Hb concentration it is possible to observe imminent postoperative bleeding and autologous retransfusions. Currently, invasive methods are used to measure the Hb concentration. For this purpose blood is taken and analyzed. The disadvantage of this method is the delay between the blood collection and its analysis, which doesn't permit a real-time patient monitoring in critical situations. A non-invasive method allows pain free online patient monitoring with minimum risk of infection and facilitates real time data monitoring allowing immediate clinical reaction to the measured data.

Emission control and reduction of harmful gases produced by combustion engines is a very important task. There is need for a high resolution online detection of harmful gases. This work presents a novel optical sensor system based on newly developed LEDs working in the ultraviolet and visible wavelength range. The developed potentially low cost LED based system is able to individual detect NO2 and SO2 with high resolution (1 ppm), wide measurement range (some 1000 ppm) and temporal dynamic of up to 10 ms (stroke resolution). Fiber optics are applied to a robust free path absorption cell to resist the harsh tailpipe environment and enable the online measurement of hot gases.

Today for clearing areas from landmines, beside dogs and searching needles, almost only metal detectors are used. Metal detectors for mine clearance are high sensitive inductive sensors which react also on small metal parts. Nevertheless, they give no further information about the buried object (depth, size, shape, material). Besides, the high false alarm rate (up to 1000 per mine) makes the mine clearance a protracted and cost-intensive process. Reasons for the false alarms are "uncooperative" soils, harmless metallic objects and the low metal content in newer anti-personnel mines. In this paper a method is described which provides more information about the buried object by using image processing and signature classification, which works also in the presence of "uncooperative" soil. Based on an algorithm for soil compensation and object classification, this paper describes a handheld system with online visualization and classification. Therefore a commercial metal detector was enhanced with additional signal processing and an ultrasonic position reference system.

Today for clearing areas from landmines, beside dogs and searching needles, almost excluding metal detectors are used. Available metal detectors, specialised for mine clearance, are high sensitive also on small metal parts. Nevertheless, they give no further information about the buried object (depth, size, shape, material). Besides, the high false alarm rate of the hand-held detectors makes the mine clearance a protracted and cost-intensive process. Reasons for the high false alarm rate (up to 1000 false alarms per mine) are "uncooperative" soils, harmless metallic objects like shell splinters, but also the low metal content in newer anti-personnel mines. In this paper a method is described which provides more information about the buried object by using image processing and signature classification, which works also in the presence of "uncooperative" soil. In many cases, there are only one or two different mines in a mine-field. So it is possible to use a database with mine signatures for an automatic object classification in order to decrease the false alarm rate.

The magnetic leakage flux method is one of the commonest non-destructive methods used for finding defects or inhomogeneities in steel products, e.g. the welding line in ferromagnetic steel. The quality of welded tubes has improved in recent years so that the signal detected by the one dimensional magnetic leakage flux sensor generated by the welding line has similar amplitude to the signal generated by the inhomogeneities in the materials of the tube wall. The paper shows that the use of a three-dimensional magnetic leakage flux sensor in conjunction with a rule-based fuzzy classificator significantly improves welded-seam inspection.

A multipoint sensor on a 1 km continuous length of fibre has been investigated and proven to be capable of detecting the presence of air, ethanol and water at each of three independent sensing points using OTDR techniques. Artificial neural network signal processing techniques have allowed the resulting OTDR signals to be accurately determined using pattern recognition. Each of the U-bend evanescent wave absorption sensors were developed with 62.5 /spl mu/m polymer-clad silica fibre, which had its cladding removed in the sensing region. Although the length of the fibre used in this investigation was 1 km, longer or shorter lengths may be used as required. Earlier results from a single U-bend sensor have shown that a multilayer perceptron is required to adequately classify the data. Initial results have shown that it is possible to train a network to recognise trends such as ageing of the bare fibre when immersed in water, and therefore possible to separate out such effects from genuine changes in the measurand. It is envisaged that a more sophisticated multipoint U-bend evanescent wave sensor system will be developed, with the resulting complex signals being processed using Artificial neural network pattern recognition techniques. This will result in the development of a 'smart system', with the ability to interpret and separate relevant measurand data from the data received from cross coupling signals from external or interfering parameters as well as faults or defects detected in the fibre.