Fluctuation-enhanced sensing

We present a short survey on fluctuation-enhanced gas sensing. We compare some of its main characteristics with those of classical sensing. We address the problem of linear response, information channel capacity, missed alarms and false alarms.Comment: Keynote Talk at SPIE's 4th international symposium on Fluctuations and Noise, Conference Noise and Fluctuations in Circuits, Devices and Materials, Florence, Italy, May 20-24, 200

Vector casting for noise reduction

We report a new method for the reduction of noise from spectra. This method is based on casting vectors from one data point to the following data points of the noisy spectrum. The noise‐reduced spectrum is computed from the casted vectors within a margin that is identified by an envelope‐finder algorithm. We compared here the presented method with the Savitzky–Golay and the wavelet transform approaches for noise reduction using simulated Raman spectra of various signal‐to‐noise ratios between 1 and 25 dB and experimentally acquired Raman spectra. The method presented here performs well compared with the Savitzky–Golay and the wavelets‐based denoising method, especially at small signal‐to‐noise ratios and furthermore relies on a minimum of human input requirements

Comparability of Raman Spectroscopic Configurations: A Large Scale Cross-Laboratory Study

This is the final version. Available on open access from the American Chemical Society via the DOI in this recordThe variable configuration of Raman spectroscopic platforms is one of the major obstacles in establishing Raman spectroscopy as a valuable physicochemical method within real-world scenarios such as clinical diagnostics. For such real world applications like diagnostic classification, the models should ideally be usable to predict data from different setups. Whether it is done by training a rugged model with data from many setups or by a primary-replica strategy where models are developed on a 'primary' setup and the test data are generated on 'replicate' setups, this is only possible if the Raman spectra from different setups are consistent, reproducible, and comparable. However, Raman spectra can be highly sensitive to the measurement conditions, and they change from setup to setup even if the same samples are measured. Although increasingly recognized as an issue, the dependence of the Raman spectra on the instrumental configuration is far from being fully understood and great effort is needed to address the resulting spectral variations and to correct for them. To make the severity of the situation clear, we present a round robin experiment investigating the comparability of 35 Raman spectroscopic devices with different configurations in 15 institutes within seven European countries from the COST (European Cooperation in Science and Technology) action Raman4clinics. The experiment was developed in a fashion that allows various instrumental configurations ranging from highly confocal setups to fibre-optic based systems with different excitation wavelengths. We illustrate the spectral variations caused by the instrumental configurations from the perspectives of peak shifts, intensity variations, peak widths, and noise levels. We conclude this contribution with recommendations that may help to improve the inter-laboratory studies.COST (European Cooperation in Science and Technology)Portuguese Foundation for Science and TechnologyNational Research Fund of Luxembourg (FNR)China Scholarship Council (CSC)BOKU Core Facilities Multiscale ImagingDeutsche Forschungsgemeinschaft (DFG, German Research Foundation

Data for: Formaldehyde Detection with Chemical Gas Sensors Based on WO3 Nanowires Decorated with Metal Nanoparticles under Dark Conditions and UV Light Irradiation

Relative changes of DC resistances of WO3 doped gas sensing layers. This data were used in the joined paper. Values of DC resistances were included in the figures of the paper.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Problems of foil-based capacitor fabrication and testing

Kondensatory są powszechnie stosowanymi elementami biernymi w układach i urządzeniach elektronicznych, elektrotechnicznych oraz energetycznych. Stąd, istotnym jest, aby koszty produkcji były możliwie jak najniższe równocześnie przy zachowaniu ich wysokiej niezawodności. W pracy przedstawiono problemy napotykane podczas wytwarzania oraz testowania kondensatorów produkowanych na bazie folii polipropylenowych metalizowanych. Szczegółowo opisano zjawiska zachodzące w produkowanych kondensatorach, aby wskazać na potencjalne przyczyny powstawania ich wad, prowadzących do ewentualnych uszkodzeń.Capacitors are ubiquitous passive elements in electronics, electrotechnics and energetics. Therefore, it is important to reduce their fabrication costs while maintaining their high quality. This paper presents problems experienced during production of the foil-based capacitors. The detailed description of various phenomena in the capacitor structures are presented to point at reasons of their possible damage. The equivalent circuits of the capacitor are presented and their elements are applied to determine the capacitor quality. The main reasons of the capacitor failure result from poor quality contacts between the wound foils and the metalized layer, too low dielectric resistance isolation or voids within the capacitor structure. It has to be underlined that monitoring changes of capacitance and dielectric loss after long-term excessive charging and discharging at elevated temperature do not exclude all the samples that would collapse. Therefore, it is suggested to monitor partial discharges phenomena that would give more information about voids within the wound foils. The authors suppose that these voids can plausibly lead to the capacitor damage

Estimation of the Raman spectra resolution

Opisano parametry wpływające na rozdzielczość pomiarów widm Ramana. Następnie przedstawiono sposób wyznaczania rozdzielczości dla przykładowego układu spektrometru, wykorzystywanego w projekcie badawczym budowy przenośnego spektrometru Ramana. Wyniki analizy przeprowadzonej na podsta-wie prążków występujących w kilku pomierzonych widmach potwierdziły zgodność obliczeń z obserwowaną rozdzielczością pomiarów w przedziale 8,5÷10,5 cm-1.The Raman phenomenon and its prospective application to chemistry are described in detail in the paper. The parameters that determine the Raman spectra resolution are given. The method for estimation of the Raman spectra resolution with use of an exemplary spectrometer is presented. The method called a Full Width at Half Maximum was applied to determine the spectra resolution. The spectrometer QE65000 by Ocean Optics company is used in a portable Raman spectrometer being under construction. The spectrometer component elements are presented as well. The equations describing the spectra resolution according to the used grating, CCD sensor and input light slit are enclosed The results, obtained for a few selected spectra lines of diamond, silicon and the applied calibrating lamp confirmed the accuracy of the calculated values that belong to a range of 8,5÷10,5 cm-1. The paper shows how the spikes observed in the Raman spectra of selected chemicals were approximated by Lorentz or Gauss functions to find the spike maximum that, in general, can be placed at Raman shift somewhere between the available CCD pixels. It can be concluded that the estimated resolution is close to the value predicted by theoretical considerations and is sufficient for the portable device

Microprocessor sensor controlling system with USB interface

Zapotrzebowanie na detekcję gazów oraz zapachów wymaga konstruowania tanich urządzeń o coraz lepszej selektywności i czułości pomiarów. W pracy opisano taki układ pomiarowy, w którym zwiększenie selektywności oraz czułości uzyskano przez pomiar zjawisk fluktuacyjnych w rezystancyjnym czujniku gazów. Opisano sposób pomiaru, wybrany układ pomiarowy oraz projekt i realizację systemu mikroprocesorowego sterującego układem. W zakończeniu przedstawiono przykładowe wyniki pomiarów.There is a huge demand on developing new methods of aroma and gases detection in medicine, military or food industry with high sensitivity and selectivity. For this reason, the new method was developed to recognize odors by analysis power spectrum density of resistance fluctuations within Taguchi gas sensor. Gas mixture concentration around the gas sensor influence resistance of gas sensor. In this paper, we focus on measurement and amplification of very low level noise signal. The microcontroller system which communicates with a personal computer by USB interface was described as well