100 research outputs found
Zero-Field Readout Electronics for Planar Fluxgate Sensors Without Compensation Coil
No full textA simple and sensitive readout electronics for planar fluxgate sensors is presented. The system exploits the sense coils to directly generate the compensation static field avoiding the additional coil/s required in standard closed loop configuration, thus providing clear advantages in terms of size and cost. Moreover, feedback configurations are known to provide better linearity and stability of the system. The sensitivity of the developed demonstration system can be easily set from 13.3 to 104.9 mV/μT with nonlinearity ranging from 0.17% to 0.38% of the measuring interval, whereas the corresponding measuring intervals vary from ±301 to ±38 μT. The measuring uncertainty, the noise field spectral density, and the system bandwidth have been estimated in 12.2 nT, ≈ 10 nT/√{Hz}, and ≈1.5 Hz, respectively. The proposed measuring instrument is extremely easy to use and versatile. Moreover, due to the use of commercially available ferromagnetic material and the simple and via-less design, the proposed fluxgate sensor results in a very low cost and reliable device
An Optical Technique for Real-Time Monitoring of Hemolysis During Hemodialysis
No full textHemolysis--the lysis of red blood cells (RBCs) causing the release of free hemoglobin (Hb) into the patient's blood--is an unavoidable side effect of any extracorporeal circulation. If not promptly detected, hemolysis and the consequent free Hb can lead to severe health risks for the patient, such as thrombosis, compromised oxygen-carrying capacity that may cause injury to the brain and other organs, and, ultimately, the death of the patient. Accurate measurement methods to detect Hb have been known for a long time. However, such methods generally exploit toxic chemicals and/or are unable to distinguish the deleterious free Hb from the Hb contained inside intact RBCs; thus they are unsuitable for inline monitoring of the extracorporeal circulation. In this paper, a simple measurement method and a measuring system for early detection of hemolysis in hemodialysis (HD) are described. The developed measuring system performs an optical analysis of the dialysis fluid in order to estimate the free Hb concentration in the blood returned to the patient, thus potentially allowing for the first time the real-time and in-line quantitative monitoring of hemolysis in HD. Moreover, the noncontact features of the proposed technique and its analyses of the waste of the hemodialyzer allow both overcoming several issues related to biological risk in medical devices and easy integration into hemodialyzers already in use. Only vast clinical trials may be able to reasonably provide a significant estimation of the achievable measurement uncertainty. Nevertheless, the reported preliminary ex vivo experiments show that hemolysis can be detected with resolution and sensitivity potentially sufficient to reduce risks for patients
UV-LEDs for monitoring dialysis adequacy
No full textAbstract—New Ultraviolet (C band: 280 nm − 100 nm) lightemitting diodes (UV-C LEDs) have been characterized to evaluatetheir potential applicability in the development of a simple low–cost optical adequacy sensor for continuous online measurementson spent dialysate. This approach would allow us to avoid theuse of bulky and expensive spectrometers in the monitor systems.The reported results could be useful for the system developmenteven if different critical aspects such as LED reliability, meanlifetime, and emitted and transmitted power monitoring should betaken into consideration. Nevertheless, the experimental activityhas shown that the system can be implemented with few opticalcomponents and that the assembly can be made simple
Contactless Two-Axis Inclination Measurement System Using Planar Flux-Gate Sensor
No full textA tilt-sensitive measuring system exploiting a low-cost planar printed-circuit-board (PCB) flux-gate sensor is described. We propose a system topology that exploits two magnets and a flux-gate sensor to realize a two-axis tilt-sensitive measuring system. The sensing configuration has been investigated using electromagnetic modeling software first. Then, the prototype characterization has shown system sensitivity up to 4 V/° and integral nonlinearity (INL) down to 1%. Mainly limited by the mechanical implementation, the obtained system dynamic range is about ±3°
A simple readout electronics for automatic power controlled self-mixing laser diode systems
No full texthe paper describes a simple electronic circuit to drive a laser diode for self-mixing interferometry. The network integrates a stable commercial automatic power controller and a current mirror based readout of the interferometric signal. The first prototype version of the circuit has been realized and characterized. The system allows easily performing precise interferometric measurements with no thermostatic circuitry to stabilize the laser diode temperature and an automatic control gain network to compensate emitted optical power fluctuations. To achieve this result, in the paper a specific calibration procedure to be performed is described
A Novel Method for Noninvasive Monitoring of Ocular Fundus Status During Transpupillary Thermotherapy Treatment
No full textA novel optical method for noninvasive monitoring of the ocular fundus status is presented. The method could provide an optimal end-point for transpupillary thermotherapy treatment, thus overcoming the severe over- and under-treatment issues currently affecting about 10% of patients. The developed instrument and measurement procedure have been tested on both a mechanical eye model and animal models. The presented results demonstrate the ability of our system to potentially detect variations in both blood flow and optical properties. Much more work will be needed before the developed instrument will be ready for clinical test, nevertheless the proposed method may provide an important improvement in the treatment of several disabling ocular diseases
On the use of deep UV-LEDs for monitoring dialysis
No full textThe new UV-C LEDs have been characterized to evaluate their potential applicability in the development of a simple, low-cost optical adequacy sensor for continuous, on-line measurements on spent dialysate. This approach would allow us to avoid the use of bulky and expensive spectrometers in the monitor systems. The reported results could be useful for the system development; nevertheless, different critical aspects such as LEDs reliability, mean life time and emitted and transmitted power-monitoring should be taken in consideration
Low-Cost Imaging Photometer and Calibration Method for Road Tunnel Lighting
No full textA camera-based measuring instrument for road tunnels lighting is proposed. The system is aimed at estimating the veiling luminance as it will be perceived by a driver approaching the tunnel, thus allowing the estimation of the optimum luminance level of tunnel entrances, hence increasing the driver's safety. The proposed measuring instrument and the relative calibration method are based on a low-cost commercial grade camera and a reference standard, respectively
Light-storing photocatalyst: The possibility of activating titanium dioxide by photoluminescence
No full textIntroduction: The aim of the present work was to analyze the possibility of creating a light-storing photocatalyst material, a system that couples a phosphorescent substrate with a titania coating. The substrate could activate the titanium dioxide coating even in condition of darkness thanks to its light emission. This improvement of absorption can be achieved because the titania semiconductor is irradiated both by the direct light and by the luminescent substrate which is activated at the same time. Methods: TiO2-based sol-gel solutions were deposited on commercial borosilicate glasses containing 2 different phosphorescent pigments (emission peaks at 470 and 520 nm, respectively). Particular attention was paid to optimize the film-substrate adhesion by using a scratch test to evaluate the optimal temperature of the posttreatment step. Results and discussion: The main result is that when irradiated the photoluminescent pigments allow an increase in the photocatalytic acitivity of the coatings. The pigments are able to convert the ultraviolet component of light in order to increase the amount of energy that can be absorbed by titania. Moreover, the hydrophilicity test showed that in the absence of irradiation the phosphorescent samples are characterized by a lower loss of superhydrophilicity
A simple and robust optical scheme for self-mixing low-coherence flowmeters
No full textThe developed measuring system is based on a low-coherence source and a self-mixing (or inter- nal) detection.
The proposed optical layout exploits the reflection from the internal wall of the duct as reference arm, thus reducing system complexity, cost, size and increasing its robustness to movements of the measurand.
Moreover, the usage of a low-coherence source allows reducing the problems related to the poor definition of the volume under test (sensing region or measurement volume) typical of “coherent” self-mixing systems.
Although preliminary analysis have been performed by simply investigating the frequencies rel- ative to the maximum in the Doppler spectrum, the obtained results demonstrates that by in- creasing scatterers concentration of +300%, the system sensitivity increases of about only +20%
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