Papers by Keyword: Optical Sensors

Abstract: This study presents the long time effects of varying temperature conditions on pH-responsive films deposited on glass slides. The films were fabricated from Brilliant Yellow and poly (allylamine hydrochloride) through ionically self-assembled monolayer technique using an automated slide strainer. The absorbance of the films was monitored and the effect of varying temperature on the optical properties of the films was studied. We found that as the films are maintained at increasing temperatures their absorbance slightly decreased. As the temperature increased the percent change decreased reaching a plateau. Films kept at low temperatures of 3.24 °C and below freezing (-9.02 °C) had a small increase in absorbance. Finally, we monitored the absorbance of films kept at room temperature over a long time (128 days) and found that the films showed decreased absorbance by 19%.

Abstract: The angle-resolved scattered light sensor OS500 (made by Optosurf in Ettlingen, Germany) is an optical measuring device that is becoming more and more frequently used inindustrial applications and for the characterization of surfaces in general as well as for measuringroughness and shape. The angle-resolved measurement principle allows the statistical distributionof the gradients of a surface, resulting from the reflectance of the light at the flank angles of theareas examined, to be measured and consequently enables the geometric surface texture to beevaluated. Thus the topography of surfaces is not measured; instead the gradients are evaluated.Since the scattered light sensor measures angles and not distances, the sensor is immune to out-ofplanevibrations in the direction of measurement. Another distinct characteristic of the scattered light sensor is the high degree of sensor dynamics, which when combined with the statisticalanalysis of the surface angles, allows even the finest changes in the surface structure to be detected. Accordingly, it makes sense to use the sensor to monitor processes in which the surfaces and their structures change only slightly during the manufacturing process. One such process is so-called vibratory finishing. This process and several other manufacturing processes geared towards sustainable manufacturing methods are being examined by the “Department of Mechanical and Aerospace Engineering” at the University of California, Davis (CA, USA). On the basis of a ray tracing model, simulations calculations, meaning only virtual measurements, will demonstrate the suitability of the sensor for monitoring manufacturing.

Abstract: Highly-ordered TiO₂ nanotube arrays were fabricated by electrochemical anodizing, using titanium foils as the anode and cathode and changing the amount of fluoride (NH₄F) in the solution. The effect of synthesis parameters, such as, ethylene glycol solutions containing different amounts of water, NH₄F, anodizing voltage, and current density were studied on the optical and morphological properties. It was observed from XRD espectra, that Anatase and Rutile phases were influenced by annealing, between 300 and 723 K, for all the samples, while morphological changes were not observed. Nanotubes diameters varying beteween 20 and 50 nm with diferent length sizes were observed from SEM micrographics. A high absorption for the UV region and a gap band round of 3.1 eV were obtained from spectrophotometry measurements. The correlation between the synthesis parameters and the optical properties presented are an excellent indicator for the TiO₂ nanotubes application as optical sensors.

Abstract: In the paper the new type of mobile sensor based on optical coherence tomography is presented. For increasing the measurement range the special dynamic focusing system which moves imaging plane during axial scanning process is used. Therefore developed system allows focusing on measured layer. Additionally, for image analysis the special type of CMOS matrix (called smart-pixel camera), synchronized with a reference mirror transducer, is applied. Due to hardware realization of a fringe contrast analysis simultaneously in each pixel with high frequency, the time of measurement decreases significantly. These advantages together with a compact design allow the sensor to be used as the mobile device for measurements of surface topography, thickness of surface layers and subsurface defects detection in laboratory, workshop and out-door conditions. Calibration of the designed sensor and its application to the technological measurements of the sticker label layers are presented and discussed.

Abstract: The potential impact of optical fibre sensors embedded into medical textiles for the continuous monitoring of the patient during Magnetic Resonance Imaging (MRI) is presented. In that way, we report on several pure optical sensing technologies for pulse oximetry and respiratory movements monitoring. The technique for pulse oximetry measurement is known as NIRS (Near Infra-Red Spectroscopy) in a reflectance mode. In parallel, we tested two different optical sensor based fabric designs breathing activity detection – a macro bending sensor and a fibre Bragg grating sensor consisting in respiratory frequency measurement by intensity variation detection and optical spectral analysis.

Abstract: Many technologies, such as Radio Frequency Identification (RFID), have been developed to keep pace with rapid changes in society. Additionally, an RFID tag can be integrated with a sensor or actuator (a smart RFID), they can comprise a sensitive wireless network. The potential and utility of smart RFID techniques have increased dramatically. However, based on the distinctive characteristics of RFID and sensors/actuators, they cannot be combined simultaneously using commercial RFID techniques and materials such as poly phenylene sulfide (PPS). Conversely, smart RFID systems will be exposed to harsh environments, including temperature variations, salt corrosion, and violent impact. The current polymeric RFID packaging technique cannot withstand severe environmental conditions for a long period. This study presents a novel integrated packaging technique for sensors and RFID that is fully compatible with the complementary metal-oxide-semiconductor (CMOS) processes to identify the limitations of traditional RFID packaging methods. After several tests in harsh environments, such as strength, corrosion resistance, thermal stress, and simulated washing, the RFID and sensor operated normally. Therefore, the novel encapsulation process for RFID integrated with a sensor overcomes the bottleneck of conventional RFID packaging techniques. The potential of this novel technique is significant and provides a new approach as it achieves high performance and at a low cost. Furthermore, the proposed new technique should prove very useful in applications as smart RFID areas.

Abstract: This work aims to report results of the spatial and frequency optical detection limits of integrated arrays of 32 one-dimensional amorphous silicon thin film position sensitive detectors with nip or MIS structure, under continuous and pulsed laser operation conditions. The arrays occupy a total active area of 45 mm2 and have a plane image resolution better than 15 m with a cut-off frequency of about 6.8 kHz. The non-linearity of the array components varies with the frequency, being about 1.6% for 200 Hz and about 4% for the cut-off frequency (6.8 kHz).