prof. dr hab. inż. Janusz Smulko
Employment
- Head of Department at Department of Metrology and Optoelectronics
- Professor at Department of Metrology and Optoelectronics
Research fields
Publications
Filters
total: 187
Catalog Publications
Year 2013
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Enhancing capabilities of Atomic Force Microscopy by tip motion harmonics analysis
PublicationMotion of a tip used in an atomic force microscope can be described by the Lennard-Jones potential, approximated by the van der Waals force in a long-range interaction. Here we present a general framework of approximation of the tip motion by adding three terms of Taylor series what results in non-zero harmonics in an output signal. We have worked out a measurement system which allows recording of an excitation tip signal and its...
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A measurement system for nonlinear surface spectroscopy with an atomic force microscope during corrosion process monitoring
PublicationIn addition to traditional imaging the surface, atomic force microscopy (AFM) enables wide variety of additional measurements. One of them is higher harmonic imaging. In tapping mode the nonlinear contact between tip and specimen results in higher frequency vibrations. More information available from the higher harmonics analysis proves to be helpful for more detailed imaging. Such visualization is espe-cially useful for heterogeneous...
Year 2014
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Szumy czujników : Metody pomiarów i analizy
PublicationW pracy przedstawiono problematykę pomiarów i analizy szumów w wybranych rodzajach czujników. Przedstawiono mechanizmy powstawania szumów, metody ich pomiarów oraz analizy. W pracy występuje szereg przykładów w których szumy są źródłem informacji o zjawiskach zachodzących w otoczeniu czujnika. Praca będzie przydatna dla osób zajmujących się problematyką pomiarów i analizy sygnałow o niewielkiej intensywności.
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Supercapacitors - charge redistribution and restoring voltage
PublicationThe charge in supercapacitor is stored on electrodes and in electrolyte. The charges on electrodes create the Helmholtz double layer which is formed immediately with time constant of the order of seconds, while the charge storage in electrolyte is going on with time constant of the order of hundreds seconds. When the charged supercapacitor is shorted for few seconds, the charge from electrodes is discharged while the charge in...
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SAMPLE-AND-HOLDING METHOD FOR GAS SENSING APPLIED FOR RESISTANCE GAS SENSORS
PublicationThe DC resistance of a Taguchi gas sensor is influenced by the ambient gas. To improve the selectivity and sensitivity of a sensor the fluctuation enhanced sensing (FES) was used. The paper proposes a novel methodology of utilizing FES technique that sample composition of an ambient atmosphere and hold it for further processing (sample-and-holding technique). The method uses the heated gas sensor to sample an ambient atmosphere...
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Quality assessment of ZnO-based varistors by 1/f noise
PublicationNoise has been used as a diagnostic tool of surge arrester varistor structures comprising of ZnO grains of various type and size. The physical and electrical properties of the measured samples have been described. In the experimental study, the applied measurement system and the results of noise measurements for the selected structures of varistors designed for the continuous working voltage 280 V, 440 V and 660 V have been presented....
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Performance Analysis of the "Intelligent" Kirchhoff- Law - Johnson-Noise Secure Key Exchange
PublicationThe Kirchhoff-law - Johnson-noise (KLJN) secure key distribution system provides a way of exchanging theoretically secure keys by measuring random voltage and current through the wire connecting two different resistors at Alice’s and Bob’s ends. Recently new advanced protocols for the KLJN method have been proposed with enhanced performance. In this paper, we analyze the KLJN system and compare with the „intelligent” KLJN (iKLJN)...
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New approaches for improving selectivity and sensitivity of resistive gas sensors: A review
PublicationResistive gas sensors are very popular and reliable but suffer from low selectivity and sensitivity. Various methods have been suggested to improve both features without increasing the number of sensors in gas detection systems. Fluctuation enhanced gas sensing was proposed to improve gas detection efficiency by analyzing low-frequency resistance fluctuations, and noise parameters can be more informative than the single DC resistance...
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Fluctuation enhanced gas sensing using UV irradiated Au-nanoparticle-decorated WO3-nanowire films
PublicationWO3 nanowires (WO3-NWs) decorated with gold nanoparticles (AuNPs) were utilized in resistive gas sensor devices to detect ethanol by use of fluctuation enhanced sensing (FES). The experimental system records both DC resistance and fluctuations of the sensing film. Our data verify that the sensitivity and selectivity of the gas sensor are improved by applying FES when the sensor is stimulated with a combination of UV light and heating....
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EFFICIENCY OF GAS MIXTURES DETECTION BY RESISTIVE GAS SENSORS
PublicationResistive gas sensors are very popular and are commonly used to detect various gases and their mixtures. Their main disadvantage is very limited selectivity. Practical use of gas sensors in environmental applications (e.g., in sewage systems to protect workers, in air conditioning systems to monitor atmosphere quality) requires determination of concentration of a few mixed gases at the same time. We would like to present recent...
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Efficiency of gas mixtures detection by resistive gas sensors
PublicationResistive gas sensors are very popular and are commonly used to detect various gases and their mixtures. Theeir main disadvantage is very limited selectivity. Practical use of gas sensors in environenmental applications requires determination of concentration of a few mixed gases at the same time. We would like to present recent results of gas detection improvement by utilizing a single gas sensor and additional measurements to...
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Detection of Denatonium Benzoate (Bitrex) Remnants in Noncommercial Alcoholic Beverages by Raman Spectroscopy
PublicationIllegal alcoholic beverages are often introduced into market using cheap technical alcohol, which is contaminated by denatonium benzoate (Bitrex) of very small concentration. Bitrex is the most bitter chemical compound and has to be removed before alcohol consumption. The home-made methods utilize sodium hypochlorite to disintegrate particles of denatonium benzoate in alcohol and to remove bitter taste before trading. In this experimental...
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AUTOMATED SYSTEM FOR FLUCTUATION ENHANCED GAS SENSING
PublicationResistance gas sensors exhibit random phenomena (resistance noise) which can be utilized to improve gas sensitivity and selectivity. That new emerging technique has to be investigated to recognize optimal parameters for gas detection. It means that a measurement system has to have ability of numerous parameters adjustment (e.g., sampling frequency, heater voltage, polarization current, voltage noise amplification). That fact induced...
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Anatomy of noise in quantitative biological Raman spectroscopy
PublicationRaman spectroscopy is a fundamental form of molecular spectroscopy that is widely used to investigate structures and properties of molecules using their vibrational transitions. It relies on inelastic scattering of monochromatic laser light irradiating the specimen. After appropriate filtering the scattered light is dispersed onto a detector to determine the shift from the excitation wavelength, which appears in the form of...
Year 2015
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Waves in a short cable at low frequencies, or just hand-waving? What does physics say? (Invited paper)
PublicationWe address the question of low-frequency signals in a short cable, which are often considered as waves in engineering calculations. Such an assumption violates several laws of physics, but exact calculations can be carried out via linear network theory.
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Sensing of anesthetic drugs in blood with Raman spectroscopy
PublicationA proof-of-concept study of a Raman spectroscopy-based approach for measuring the content of anesthesia drugs in blood is presented. Spectra of spiked blood from several patients exhibit prominent changes in regions associated with the drug.
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Noise in biological Raman spectroscopy
PublicationRaman spectroscopy is a widely used method to investigate chemical molecules by analyzing their vibrational transitions. It utilizes inelastic scattering of the laser light irradiating the investigated object. The scattered light requires appropriate filtering to reduce dominant laser light and expose much weaker components having shifted wavelengths of a characteristic spectral pattern. These components are measured by dispersing...
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Nickel Oxide Thin Film Sensor for Fluctuation-Enhanced Gas Sensing of Formaldehyde
PublicationNanocrystalline nickel-oxide-based thin films were prepared by advanced reactive gas deposition, and the response of these films to formaldehyde was studied by fluctuationenhanced sensing. Morphological and structural analyses showed porous deposits of nickel oxide particles with face-centered cubic structure. Resistance fluctuations were measured upon exposure to ethanol, formaldehyde and methane at 200 °C. Power density spectra...
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New approaches for improving selectivity and sensitivity of resistive gas sensors: a review
PublicationPurpose – This paper aims to present the methods of improving selectivity and sensitivity of resistance gas sensors. Design/methodology/approach – This paper compares various methods of improving gas sensing by temperature modulation, UV irradiation or fluctuation-enhanced sensing. The authors analyze low-frequency resistance fluctuations in commercial Taguchi gas sensors and the recently developed tungsten trioxide (WO3) gas-sensing...
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Method of selecting the LS-SVM algorithm parameters in gas detection process
PublicationIn this paper we showed the method of resistive gas sensors data processing. The UV irradiation and temperature modulation was applied to improve gas sensors’ selectivity and sensitivity. Noise voltage across the sensor’s terminals (proportional to its resistance fluctuations) was recorded to estimate power spectral density. This function was an input data vector for LS-SVM (least squares – support vector machine) algorithm, which...
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Gas selectivity enhancement by sampling-and-hold method in resistive gas sensors
PublicationCommercial resistive gas sensors exhibit various sensitivity to numerous gases when working at different elevated temperatures. That effect is due to a change in velocity of adsorption and desorption processes which can be modulated by temperature. Thus, to reach better selectivity of gas detection, we propose to apply a known method (called the sampling-and-hold method) of cooling down the gas sensor in the presence of the investigated...
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Efficiency of gas detection algorithms using fluctuation enhanced sensing
PublicationEfficiency of various gas detection algorithms by applying fluctuation enhanced sensing method was discussed. We have analyzed resistance noise observed in resistive WO3- nanowires gas sensing layers. Power spectral densities of the recorded noise were used as the input data vectors for two algorithms: the principal component analysis (PCA) and the support vector machine (SVM). The data were used to determine gas concentration...
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Determination Of Gas Mixture Components Using Fluctuation Enhanced Sensing And The LS-SVM Regression Algorithm
PublicationThis paper analyses the effectiveness of determining gas concentrations by using a prototype WO3 resistive gas sensor together with fluctuation enhanced sensing. We have earlier demonstrated that this method can determine the composition of a gas mixture by using only a single sensor. In the present study, we apply Least-Squares Support-Vector-Machine-based (LS-SVM-based) nonlinear regression to determine the gas concentration...
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Critical Remarks on Landauer’s principle of erasure– dissipation: Including notes on Maxwell demons and Szilard engines
PublicationWe briefly address Landauer’s Principle and some related issues in thermal demons. We show that an error-free Turing computer works in the zero-entropy limit, which proves Landauer’s derivation incorrect. To have a physical logic gate, memory or information-engine, a few essential components necessary for the operation of these devices are often neglected, such as various aspects of control, damping and the fluctuation–dissipation...
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Computational complexity and length of recorded data for fluctuation enhanced sensing method in resistive gas sensors
PublicationThis paper considers complexity and accuracy of data processing for gas detection using resistance fluctuation data observed in resistance gas sensors. A few selected methods were considered (Principal Component Analysis – PCA, Support Vector Machine – SVM). Functions like power spectral density or histogram were used to create input data vector for these algorithms from the observed resistance fluctuations. The presented considerations...
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Analytical fluctuation enhanced sensing by resistive gas sensors
PublicationResistance fluctuations across polarised resistive gas sensors were studied in detail to evaluate sensor working conditions for detecting methane and ammonia at various concentrations. The 1/f noise component typically dominates other noise sources up to a few kHz and can be utilised to improve gas selectivity when compared with measurements of the sensor DC resistance. The Arrhenius plot was created and the activation energy for...
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Analysis of an Attenuator Artifact in an Experimental Attack by Gunn–Allison–Abbott Against the Kirchhoff-Law–Johnson-Noise (KLJN) Secure Key Exchange System
PublicationA recent paper by Gunn–Allison–Abbott (GAA) [L. J. Gunn et al., Scientific Reports 4 (2014) 6461] argued that the Kirchhoff-law–Johnson-noise (KLJN) secure key exchange system could experience a severe information leak. Here we refute their results and demonstrate that GAA’s arguments ensue from a serious design flaw in their system. Specifically, an attenuator broke the single Kirchhoff-loop into two coupled loops, which is an...
Year 2016
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UV-Light-Induced Fluctuation Enhanced Sensing by WO3-Based Gas Sensors
PublicationWO3-based gas sensors were investigated under UV-light irradiation and at different working temperatures with the object of achieving superior sensitivity and selectivity. Resistance fluctuations in the WO3 layer were studied together with dc resistance measurements. The data were taken in synthetic air, ethanol, nitrogen dioxide, and mixtures of these gases. We conclude that UV irradiation can easily be applied to enhance the...
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System of breath collection and analysis for diseases detection
PublicationCollection and study of composition of the exhaled air is now intensively investigated to develop non-invasive medical diagnostics based on presence of metabolic compounds in the exhaled air. The process of collecting and processing of the exhaled air must fulfill relevant conditions to achieve satisfactory results. The paper presents the system of collecting samples of exhaled breath and the proposed methods of its analysis, using...
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Resistive gas sensors – Perspectives on selectivity and sensitivity improvement
PublicationResistive gas sensors are very popular and relatively inexpensive; they can operate at elevated or room temperature for years on end. The main disadvantage of resistive gas sensors is their limited selectivity and sensitivity, but various methods have been applied to improve their behavior. The composition of the porous gas sensing layer, or changes in the sensor’s operating temperature, can enhance the gas detection ability. Furthermore, emerging...
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Gas Detection Using Resistive Gas Sensors And Radial Basis Function Neural Networks
PublicationWe present a use of Radial Basis Function (RBF) neural networks and Fluctuation Enhanced Sensing (FES) method in gas detection system utilizing a prototype resistive WO3 gas sensing layer with gold nanoparticles. We investigated accuracy of gas detection for three different preprocessing methods: no preprocessing, Principal Component Analysis (PCA) and wavelet transformation. Low frequency noise voltage observed in resistive gas...
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Fluctuation-Enhanced Sensing with Organically Functionalized Gold Nanoparticle Gas Sensors Targeting Biomedical Applications
PublicationDetection of volatile organic compounds is a useful approach to non-invasive diagnosis of diseases through breath analysis. Our experimental study presents a newly developed prototype gas sensor, based on organically-functionalized gold nanoparticles, and results on formaldehyde detection using fluctuation-enhanced gas sensing. Formaldehyde was easily detected via intense fluctuations of the gas sensor’s resistance, while the cross-influence...
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Fluctuation enhanced gas sensing with WO3-based nanoparticle gas sensors modulated by UV light at selected wavelengths
PublicationThe sensitivity and selectivity of WO3-based gas sensors can be enhanced by UV-irradiation-induced modulation, especially if different wavelengths are employed. We used fluctuation-enhanced gas sensing, based on measurements of resistance fluctuations in the gas sensor, to study the effects of such modulation on the noise intensity for ambient atmospheres of synthetic air without and with additions of small amounts of ethanol,...
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Detection of gaseous compounds with different techniques
PublicationSensing technology has been developed for detection of gases in some environmental, industrial, medical, and scientific applications. The main tasks of these works is to enhance performance of gas sensors taking into account their different applicability and scenarios of operation. This paper presents the descriptions, comparison and recent progress in some existing gas sensing technologies. Detailed introduction to optical sensing...
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Anti-theft lab security system based on RFID
PublicationThe aim of the project is to design and create an electronic system, which can be used to protect laboratory equipment against theft. The main task of the system is to warn a person responsible for the facilities about any attempts made to steal equipment from a laboratory. In a case of an alarm situation, the system emits a sound signal. The concept of the anti-theft security system based on RFID was developed on the basis of...
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ANALYSIS OF EFFECTIVENESS AND COMPUTATIONAL COMPLEXITY OF TREND REMOVAL METHODS
PublicationThe paper presents a method of processing measurement data due to remove slowly varying component of the trend occurring in the recorded waveforms. Comparison of computational complexity and trend removal efficiency between some commonly used methods is presented. The impact of these procedures on probability distribution and power spectral density is shown. Effectiveness and computational complexity of these methods depend essentially...
Year 2017
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Non-Gaussian Resistance Fluctuations in Gold-Nanoparticle-Based Gas Sensors: An Appraisal of Different Evaluation Techniques
PublicationVolatile organic compounds, such as formaldehyde, can be used as biomarkers in human exhaled breath in order to non-invasively detect various diseases, and the same compounds are of much interest also in the context of environmental monitoring and protection. Here, we report on a recently-developed gas sensor, based on surface-functionalized gold nanoparticles, which is able to generate voltage noise with a distinctly non-Gaussian...
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Noise sources in Raman spectroscopy of biological objects
PublicationWe present an overview of noise sources deteriorating the quality of the recorded biological Raman spectra and the ability to determine the specimen composition. The acquired Raman spectra exhibit intense additive noise components or drifts because of low intensity of the scattered light. Therefore we have to apply expensive or bulky measurement setups to limit their inherent noise or to apply additional signal processing to reduce...
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Measurements of flicker noise in supercapacitor cells
PublicationFlicker noise (1/f-like noise) is often used to assess the quality of various materials and devices. This phenomenon has been observed in different electrochemical devices or reactions (e.g., smart windows, pitting corrosion events). In our exploratory studies we consider how to measure and utilize 1/f noise for the quality assessment of supercapacitors. This task requires special attention because of enormous capacitance of the...
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Fluctuation-enhanced and conductometric gas sensing with nanocrystalline NiO thin films: A comparison
PublicationNanocrystalline thin films of NiO were prepared by advanced reactive gas deposition, and their responses to formaldehyde, ethanol and methane gases were studied via fluctuation-enhanced and conductometric methods Thin films with thicknesses in the 200–1700-nm range were investigated in as-deposited form and after annealing at 400 and 500 °C. Morphological and structural analyses showed porous deposits with NiO nanocrystals having...
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Feasibility study of a Raman spectroscopic route to drug detection
PublicationWe present an surface-enhanced Raman spectroscopy (SERS) approach for detection of drugs of abuse in whole human blood. We utilize a near infrared laser with 830 nm excitation wavelength in order to reduce the influence of fluorescence on the spectra of blood. However, regular plasmon resonance peak of plasmonic nanoparticles, such as silver or gold fall in a much lower wavelength regime about 400 nm. Therefore, we have shifted...
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Corrosion process monitoring by AFM higher harmonic imaging
PublicationThe atomic force microscope (AFM) was invented in 1986 as an alternative to the scanning tunnelling microscope, which cannot be used in studies of non-conductive materials. Today the AFM is a powerful, versatile and fundamental tool for visualizing and studying the morphology of material surfaces. Moreover, additional information for some materials can be recovered by analysing the AFM's higher cantilever modes when the cantilever...
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Assessment of Supercapacitor’s Quality by Means of Low Frequency Noise
PublicationLow frequency noise is a well-known tool for quality and reliability assessment of electronic devices. This phenomenon is observed in different electrochemical devices as well (e.g., smart windows, electrochemical corrosion processes). Thus, we can assume that the same tool can be used to asses quality of supercapacitors. Their quality is usually determined only by capacitance and/or equivalent series resistance (ESR), or impedance....
Year 2018
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Portable exhaled breath analyzer employing fluctuation-enhanced gas sensing method in resistive gas sensors
PublicationThis paper presents a portable exhaled breath analyser, developed to detect selected diseases. The set-up employs resistive gas sensors: commercial MEMS sensors and prototype gas sensors made of WO3 gas sensing layers doped with various metal ingredients. The set-up can modulate the gas sensors by applying UV light to induce physical changes of the gas sensing layers. The sensors are placed in a tiny gas chamber of a volume...
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Exhaled breath gas sensing using pristine and functionalized WO3 nanowire sensors enhanced by UV-light irradiation
PublicationThe development of advanced metal-oxide-semiconductor sensing technologies for the detection of Volatile Organic Compounds (VOCs) present in exhaled breath is of great importance for non-invasive, cheap and fast medical diagnostics. Our experimental studies investigate the effects of operating temperature selection and UV-light irradiation on improving the response of WO3 nanowire sensors towards exhaled breath exposure. Herein,...
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APPLICATION OF STATISTICAL FEATURES AND MULTILAYER NEURAL NETWORK TO AUTOMATIC DIAGNOSIS OF ARRHYTHMIA BY ECG SIGNALS
PublicationAbnormal electrical activity of heart can produce a cardiac arrhythmia. The electrocardiogram (ECG) is a non-invasive technique which is used as a diagnostic tool for cardiac diseases. Non-stationarity and irregu- larity of heartbeat signal imposes many difficulties to clinicians (e.g., in the case of myocardial infarction arrhythmia). Fortunately, signal processing algorithms can expose hidden information within ECG signal contaminated...
Year 2019
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Noise in electrical double-layer capacitors (EDLCs)
PublicationWe present methods and problems of noise measurements in electrical double-layer capacitors (EDLC). Detailed noise equivalent electronic circuit is considered, and two possible ways of observations of random processes generated in the EDLCs structures are studied. We conclude that noise is a useful tool for characterization of the EDLC structures and their state-of-health, as in other materials and electronic devices. Eventual,...
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Methods of trend removal in electrochemical noise data – overview
PublicationIn this paper we shall review popular methods of trend removal from electrochemical noise time records. The basic principles of operation of the six most popular methods are explained. The proposed methods are: high - pass filtering, Moving Average Removal, polynomial detrending, wavelet detrending, Empirical Mode Decomposition and Variational Mode Decomposition. Estimation of trend removal quality...
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Methods of Assessing Degradation of Supercapacitors by Using Various Measurement Techniques
PublicationThis article presents the qualitative analyses of the construction of supercapacitor samples. The analyses are based on the suggested thermographic measurements as well as the technique of testing the inherent noise of the investigated element. The indicated assessment methods have been referred to the currently used parameters for the qualitative evaluation of supercapacitors. The approach described in this paper, which introduces...
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Influence of silver-core gold-shell nanoparticle parameters on the variation of surface-enhanced Raman spectra
PublicationThe detection of molecules by surface-enhanced Raman spectroscopy (SERS) is dependent on the nanomaterial used to induce the enhancement effect. This depends on a variety of parameters of the substrate such as the metal used for their creation, their shape, size and size distribution, concentration, as well as the parameters of the solution, such as packing of the nanoparticles, the complexity of the sample, the solvent, etc. It...
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