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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.

In this paper, we will present the development of a compact LED-based optical gas sensing system in the ultraviolet-C spectral region. This includes the design of the LED heterostructure emitting near 226 nm, the development of an LED chip, and the implementation into a gas sensing system capable of detecting nitrogen oxide concentrations in the ppm range.

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.

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 method for noninvasive determination of fat and water content in the human body is examined. A spatially resolved spectroscopy method is used which can record low intensity near infrared spectra. This novel approach is compared to other methods for the determination of fat and water content. Monte Carlo simulations of light propagation in tissue are shown and the production and characterization of optical phantoms of adipose tissue are investigated.

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.

Background Contemporary resuscitation guidelines for basic life support recommend an immediate onset of cardiac compressions in case of cardiac arrest followed by rescue breaths. Effective ventilation is often omitted due to fear of doing harm and fear of infectious diseases. In order to improve ventilation a pre-stage of an automatic respirator was developed for use by laypersons. Methods Fifty-two healthy volunteers were ventilated by means of a prototype respirator via a full-face mask in a pilot study. The pre-stage public access ventilator (PAV) consisted of a low-cost self-designed turbine, with sensors for differential pressure, flow, FO2, FCO2 and 3-axis acceleration measurement. Sensor outputs were used to control the respirator and to recognize conditions relevant for efficiency of ventilation and patients’ safety. Different respiratory manoeuvres were applied: a) pressure controlled ventilation (PCV), b) PCV with controlled leakage and c) PCV with simulated airway occlusion. Sensor signals were analysed to detect leakage and airway occlusion. Detection based upon sensor signals was compared with evaluation based on clinical observation and additional parameters such as exhaled CO2. Results Pressure controlled ventilation could be realized in all volunteers. Leakage was recognized with 93.5% sensitivity and 93.5% specificity. Simulated airway occlusion was detected with 91.8% sensitivity and 91.7% specificity. Conclusion The pre-stage PAV was able to detect potential complications relevant for patients’ safety such as leakage and airway occlusion in a proof of principle study. Prospectively, this device provides a respectable basis for the development of an automatic emergency respirator and may help to improve bystander resuscitation. Electronic supplementary material The online version of this article (10.1186/s12873-017-0150-5) contains supplementary material, which is available to authorized users.

The pulse oximetry is a non-invasive method to monitor the oxygen saturation and is clinically used for many years. However this technology has some limitations. In case of the presence of dysfunctional hemoglobin derivatives as carboxyhemoglobin (COHb) or methemoglobin (MetHb) the readings of the pulse oximeter are distorted. This erroneous diagnosis of the patient’s status can result in a life threatening situation. This paper will describe a sensor system for noninvasive determination of carboxy- and methemoglobin.

Implant osseointegration can currently only be assessed reliably post mortem. A novel method that relies on the principle of acoustic sound analysis was developed to enable examination of the longitudinal progress of osseointegration. The method is based on a magnetic sphere inside a hollow cylinder of the implant. By excitation using an external magnetic field, collision of the sphere inside the implant produces a sound signal. Custom-made titanium implants equipped thusly were inserted in each lateral femoral epicondyle of 20 New Zealand White Rabbits. Two groups were investigated: Uncoated, machined surface versus antiadhesive surface; and calcium phosphate-coated surface versus antiadhesive surface. The sound analysis was performed postoperatively and weekly. After 4 weeks, the animals were euthanized, and the axial pull-out strengths of the implants were determined. A significant increase in the central frequency was observed for the loose implants (mean pull-out strength 21.1 ± 16.9 N), up to 6.4 kHz over 4 weeks. In comparison, the central frequency of the osseointegrated implants (105.2 ± 25.3 N) dropped to its initial value. The presented method shows potential for monitoring the osseointegration of different implant surfaces and could considerably reduce the number of animals needed for experiments. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:606–612, 2014.

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.

The design and development of a Zigbee smart noninvasive wearable physiological parameters monitoring device has been developed and reported in this paper. The system can be used to monitor physiological parameters, such as temperature and heart rate, of a human subject. The system consists of an electronic device which is worn on the wrist and finger, by an at-risk person. Using several sensors to measure different vital signs, the person is wirelessly monitored within his own home. An impact sensor has been used to detect falls. The device detects if a person is medically distressed and sends an alarm to a receiver unit that is connected to a computer. This sets off an alarm, allowing help to be provided to the user. The device is battery powered for use outdoors. The device can be easily adapted to monitor athletes and infants. The low cost of the device will help to lower the cost of home monitoring of patients recovering from illness. A prototype of the device has been fabricated and extensively tested with very good results.

In this paper, we present a new approach for the enhancement of the bone proliferation rate by electrostimulation in the acetabular region. Based on the complex tissue structure in this area, the electric field distributions were computed by numerical means using a model based on high-resolution computed tomography scans of the acetabular area. This results in a complex, nonlinear, and discrete optimization problem. Therefore, an adapted algorithm was developed to reduce the computational effort in the order of several magnitudes. We divided the procedure into two stages: data extraction and a subsequent optimization process. The used optimization algorithm utilizes an evolutionary concept and a multidimensional definition of optimality for different, partly contradictive objective functions. Finally, we present first optimization results for different stimulation situations.

Photo-plethysmography (PPG) is frequently used in research on microcirculation of blood. Usually PPG time series are analyzed by conventional linear methods, mainly Fourier analysis. These methods may not be optimal for the investigation of nonlinear effects of the heart circulation system like vasomotion, autoregulation, thermoregulation, breathing, heartbeat and vessels. PPG is a non-invasive procedure and takes minimal time to be carried out. The wavelet analysis of the PPG time series is a specific, sensitive nonlinear method for the in vivo identification of heart circulation patterns and human health status. This nonlinear analysis of PPG signals provides additional information which cannot be detected using conventional approaches. The wavelet analysis has been used to study healthy subjects and to characterize the health status of patients with a functional cutaneous microangiopathy which was associated with diabetic neuropathy. Additionally the fact that the absorption-coefficients μ a and scattering-coefficients μ s for blood differ at different wavelengths has been exploited and is used for calculation of the optical absorbability characteristics of human blood yielding information on blood components like hemoglobin and oxygen saturation. The measured PPG time signals and the ratio between the peak to peak pulse amplitudes are used for a measurement of these parameters. A newly developed PMD device has been introduced. The non-invasive in-vivo multi-spectral method is based on the radiation of monochromatic light, emitted by laser diodes, through an area of skin on the finger. Delays between the proportions of hemoglobin and plasma in the intravasal volume should be detected photo-electrically by signal-analytic evaluation of the signals. The computed nonlinear coefficients are used for the measurement and calculation of the relative hemoglobin concentration change. Results with this photometric method to measure changes in the hemoglobin concentration were demonstrated during measurements with a hemodynamic model and healthy subjects. The PMD is suitable for non-invasive continuous on-line monitoring of one or more biologic constituent values. The objective of this development is to reduce the dependence on measurement techniques which require that a sample of blood be withdrawn from the patient for in-vitro analysis. Any invasive method used on the patient to obtain blood is accompanied by problems of inconvenience, stress, and discomfort. The patient is also exposed to the normal risks of infection associated with such invasive methods.

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.

The LED-based spectroscope is described. Example measurements using the gases O3, SO2, and NO2 are given. The unique properties of UV-LEDs are utilized in combination with standard broadband photodiodes (PD). These low-cost components can be arranged in a simple design which produces cost-effective but high-resolution sensors compared with current state-of-the-art measurement systems. Broad UV absorption lines/bands are well suited for UV emitter-based sensing.

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.

The development of the photometric device described here is based on the realization of a photoplethysmography measurement device developed for the German Space Agency DLR. It is well known in biomedical engineering that pulsatile changes of blood volume in tissue can be observed by measuring the transmission or the reflection of light (Roberts 1982 Trans. Inst. Meas. Control 4 101–6). The non-invasive multi-spectral method described here is based on the radiation of monochromatic light, emitted by laser diodes in the range 600–1400 nm, through an area of skin on the finger. After interaction with the tissue the transmitted light is detected non-invasively by photo-diodes. The method makes use of the intensity fluctuations caused by the pulse wave. The ratio between the peak to peak pulse amplitudes measured at different wavelengths and its dependence on the optical absorbability characteristics of human blood yields information on the blood composition. Deferrals between the proportions of haemoglobin and water in the intravasal volume should be detected photo-electrically by signal-analytic evaluation of the signals. The computed coefficients are used for the measurement and calculation of the arterial oxygenic saturation (SaO2) and the relative haemoglobin concentration change. Results of clinical measurements are presented for a deoxygenation study with ICG-bolus injection (indocyanine green).

Preliminary results are presented for a multi-point optical fibre sensor designed to detect the presence of chemical species in water at spatial intervals of greater than 20 m. The sensor is addressed using optical time domain reflectometry (OTDR) with a spatial resolution of 10 m. The optical signals arising from the OTDR are highly complex due to interfering effects from external parameters such as localised fibre straining and temperature changes. Because of this level of complexity it has been found advantageous to use artificial neural networks (ANNs) as classifiers on the OTDR signals. The preliminary system has been trained initially to recognise only the presence of water, although it is planned to extend this capability to recognise the presence of contaminants in the water such as bacteria and chemical pollutants. Initial investigations show that different contaminants and interfering parameters (cross-sensitivities) may give rise to characteristic signatures on the OTDR signal which may be identified by the pattern recognition software.

Preliminary results are presented for a multi-point optical fibre sensor designed to detect the presence of chemical species in water at spatial intervals of greater than 20 m. The sensor is addressed using optical time domain reflectometry (OTDR) with a spatial resolution of 10 m. The optical signals arising from the OTDR are highly complex due to effects such as interference from external parameters such as localised fibre straining and temperature changes. Because of this level of complexity it has been necessary to use artificial neural networks (ANN) and pattern recognition techniques on the OTDR signals. The preliminary system has been trained initially to recognise only the presence of water, although it is planned to extend this capability to recognise the presence of contaminants in the water such as bacteria and chemical pollutants. Initial investigations show that different contaminants and interfering parameters (cross-sensitivities) may give rise to characteristic signatures on the OTDR signal which may be identified by the pattern recognition software.

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.

During the perioperative period, which includes the period before surgery and after surgery (postoperative), it is essential to measure diagnostic parameters such as: blood oxygen saturation; hemoglobin (Hb) concentration; and pulse rate. The Hb concentration in human blood is an important parameter to evaluate the physiological condition of an individual, as Hb is the oxygen carrying component of red blood cells. By determining the Hb concentration, it is possible, for example, to observe intraoperative or postoperative bleeding, and use this information as a trigger for autologous/ allogenic blood transfusions. In blood donation center it is also an essential parameter for the decision regarding the acceptance of the donor.

Hemoglobin (Hb) is an important component of red blood cells. The primary function of Hb is the transport of oxygen from the lungs to the tissue and carbon dioxide back to the lungs. The Hb concentration in human blood is an important parameter in evaluating the physiological status of an individual and an essential parameter in every blood count. Invasive methods are used to measure the Hb concentration, whereby blood is taken from the patient and subsequently analyzed. Apart from the discomfort of drawing blood samples, an added disadvantage of this method is the delay between the blood collection and its analysis, which does not allow real time patient monitoring in critical situations. A non-invasive method allows pain free continuous on-line patient monitoring with minimum risk of infection and facilitates real time data monitoring allowing immediate clinical reaction to the measured data.

Simulations of light propagation in biological tissues are a useful method in detector development for tissue spectroscopy. In practice most attention is paid to the adequate description of tissue structures and the ray trace procedure. The surrounding light source geometry, such as output window, reflector and casing is neglected. Instead, the description of the light source is usually reduced to incident beam paths. This also applies to detectors and further surrounding tissue connected sensor geometry. This paper discusses the influence of a complex and realistic description of the light source and detector geometry with the ray tracing software ASAP (Breault Research Organization). Additionally simulations include the light distribution curve in respect to light propagation through the tissue model. It was observed that the implementation of the geometric elements of the light source and the detector have direct influence on the propagation paths, average photon penetration depth, average photon path length and detected photon energy. The results show the importance of the inclusion of realistic geometric structures for various light source, tissue and sensor scenarios, especially for reflectance measurements. In reality the tissue surrounding sensor geometry has a substantial impact on surface and subsurface reflectance and transmittance due to the fact that a certain amount of photons are prevented from leaving the tissue model. Further improvement allows a determination of optimal materials and geometry for the light source and sensors to increase the number of light-tissue-interactions by the incident photons.

Where pain is experienced following a total hip replacement (THR), there needs to be clarification as to whether the cause is due to an infected or mechanically loose THR. The major complication after implantation of a THR is aseptic loosening, caused by stress shielding and wear-particle induced osteolysis with an incidence of 75 % (Malchau et al., 2002). A further prevalent reason for implant loosening is a sepsis due to infection of the periprosthetic membrane. The optimal management in case of hip pain is an often discussed controversy. Currently, several diagnostic methods are used to identify the loosening status of the THR and to establish a basis for revision management. All these techniques are based on imaging methods. An overview of the main imaging methods used is given in figure 1. Although the devices and technology are highly developed, a 100 % diagnostic accuracy is not available (Temmerman et al., 2005). Plain radiographs are mainly used to identify the loosening status of a THR and most decisions on how to treat disorders after THR can be made (Ostlere & Soin, 2003). The time period between e.g. the onset of an infection and the possibility to identify any changes within the THR can be very long (Itasaka et al., 2001). Hence, in early loosening diagnosis, identifying radiolucent lines or increased uptake in radionuclide scanning can be very complex owing to the difficulty with excluding loosening (Love et al., 2001; Udomkiat et al., 2001). Therefore, surgeons cannot verify the actual loosening status accurately until the point of surgical intervention. Thus, the surgeon carries the risk of revising a sufficiently integrated THR. A major clinical problem in diagnosing loosening of a THR is to identify the moment where revision surgery is required. Loosening of THR should be diagnosed precisely and early in order to avoid massive osteolysis of the femur.

Novel III-Nitride based DUV-LEDs with peak emission wavelengths in the range of 225–230 were used to develop and demonstrate sensor for selective optical detection of NO in combustion gases.

Novel Deep UV-LEDs enabled a portable sensor device for high resolution detection of Ozone in the ppm and ppb range.

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.

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.

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. It will be explained what the sensors field of application is and the difficulties to handle with. Furthermore, solutions for reducing the side metal effect are explained and evaluated.

Magnetic and inductive sensors are widely used in research and industry for a variety of applications, e.g. for geophysical prospecting, nondestructive testing (NDT) of materials, in the food industries, for distance and proximity sensing, security systems as well as for landmine detection. Metal detectors (MD), based on the eddy current principle, are the most used systems in humanitarian demining. Their main disadvantage is the high false alarm rate, caused by harmless metal objects and "uncooperative" soils with magnetic properties. The sensor signal (i.e. the induced complex coil voltage) is influenced by the object properties (material, shape). This paper describes an object recognition based on multi-parameter MD signals, which are classified by the fuzzy method. The ability to identify mines by their characteristic signature was demonstrated in test lanes for mine detection provided by the University of Rostock (Germany), JRC-Ispra (Italy) and the CTRO-Benkovac (Croatia).

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.

NIR-spectroscopy and Photoplethysmography (PPG) is used for a measurement of blood components. The absorptioncoefficient 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), carboxyhemoglobin (CoHb) and arterial oxygen saturation (SpO2). The measured PPG time signals and the ratio between the peak to peak pulse amplitudes are used for a measurement of these parameters. Hemoglobin is the main component of red blood cells. The primary function of Hb is the transport of oxygen from the lungs to the tissue and carbon dioxide back to the lungs. The Hb concentration in human blood is an important parameter in evaluating the physiological status of an individual and an essential parameter in every blood count. Currently, invasive methods are used to measure the Hb concentration, whereby blood is taken from the patient and subsequently analyzed. Apart from the discomfort of drawing blood samples, an added disadvantage of this method is the delay between the blood collection and its analysis, which does not allow real time patient monitoring in critical situations. A noninvasive method allows pain free continuous on-line patient monitoring with minimum risk of infection and facilitates real time data monitoring allowing immediate clinical reaction to the measured data.

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.

peer-reviewed Hemoglobin (Hb) is an important component of red blood cells. The primary function of Hb is to transport oxygen from the lungs to the body tissues and to carry carbon dioxide back to the lungs from the body tissues. The Hb concentration in human blood is an important parameter in evaluating the physiological status of an individual and an essential parameter in every blood count. Currently, invasive methods are used to measure the Hb concentration, whereby blood is taken from a patient and subsequently analyzed. Apart from the discomfort of drawing blood samples, there is often a substantial delay between the blood collection and its analysis in the laboratory. This process delay does not allow real-time patient monitoring in acute situations. However, the herein described noninvasive method allows pain free continuous on-line patient monitoring. The real-time monitoring of Hb facilitates immediate clinical reaction if necessary. PUBLISHED peer-reviewed

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.