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1

Portable exhaled breath analyzer employing fluctuation-enhanced gas sensing method in resistive gas sensors

Kwiatkowski A., Chludziński T., Smulko J.

Metrology and Measurement Systems

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2018

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Vol. 25, nr 3

551--560

EN

This 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 of about 22 ml. Breath samples can be either injected or blown into the gas chamber when an additional pump is used to select the last breath phase. DC resistance and resistance fluctuations of selected sensors using separate channels are recorded by an external data acquisition board. Low-noise amplifiers with a selected gain were used together with a necessary bias circuit. The set-up monitors other atmospheric parameters interacting with the responses of resistive gas sensors (humidity, temperature, atmospheric pressure). The recorded data may be further analysed to determine optimal detection methods.

2

Measurement of Noise in Supercapacitors

Szewczyk A.

Metrology and Measurement Systems

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2017

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Vol. 24, nr 4

645--652

EN

A developed method and measurement setup for measurement of noise generated in a supercapacitor is presented. The requirements for noise data recording are considered and correlated with working modes of supercapacitors. An example of results of low-frequency noise measurements in commercially available supercapacitors are presented. The ability of flicker noise measurements suggests that they can be used to assess quality of tested supercapacitors.

3

Estimating the noise-related error in continuous-time integrator-based ADCs

Gosselin P., Koukab A., Kayal M.

International Journal of Microelectronics and Computer Science

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2016

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Vol. 7, nr 2

54--59

EN

From first-order incremental ΣΔ converters to controlled-oscillator-based converters, many ADC architectures are based on the continuous-time integration of the input signal. However, the accuracy of such converters cannot be properly estimated without establishing the impact of noise. In fact, noise is also integrated, resulting in a random error that is added to the measured value. Since drifting phenomena may make simulations and practical measurements unable to ensure longterm reliability of the converters, a theoretical tool is required. This paper presents a solution to compute the standard deviation of the noise-generated error in continuous-time integrator-based ADCs, under the assumption that a previous measure is used to calibrate the system. In addition to produce a realistic case, this assumption allows to handle a theoretical issue that made the problem not properly solvable. The theory is developed, the equations are solved in the cases of pure white noise, pure flicker noise and low-pass filtered white noise, and the implementation issues implied by the provided formulas are addressed.

4

Sigma-delta modulator for force measurement based on the use of a flip-flop circuit and presentation of simulated results

Kollar M.

Metrology and Measurement Systems

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2004

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Vol. 11, nr 1

3-19

EN

This paper describes a flip-flop circuit-based sigma-delta modulator for force measurement. The main part of the proposed system is a modified flip-flop used as a comparator, inside of which switched capacitors replace the classical load resistors. The functional principle lies in the fact that if capacitive asymmetry caused by the force to be measured, is such that the flip-flop holds a stable state where, for example, a higher voltage is on a second transistor, then it produces a higher force between the parallel plates connected to the same transistor to decrease the resulting capacitive asymmetry. The main advantage of the flip-flop, besides its simplicity, is the compensation of the influence of flicker noise, which is mathematically described in this paper. The theoretical conclusions are compared with the results of simulations with TSPICE and Matlab-Simulink, with respect to the measurement system realized in 0.8 [mi]m CMOS technology. The results were in agreement with theoretical results.

PL

Artykuł przedstawia modulator typu sigma-delta do pomiaru siły. Główną jego częścią jest zmodyfikowany układ komparatora oparty na przerzutnikach, w którym pojemności przełączane zastępują klasyczne rezystory. Zasada działania opiera się na zjawisku zakłócenia asymetrii pojemności mierzoną siłą. Główną zaletą użycia przerzutników w tym układzie, poza ich prostotą, jest kompensacja wpływu szumów typu flicker, co udowodniono w pracy. Wnioski teoretyczne są zgodne z wynikami symulacji dokonanych w TSPICE i pakiecie Matlab-Simulink. Układ opracowano w technologii CMOS 0.8 mikrometra.

5

1/f ɑ noise in nanopores and its potential application in biosensors

Kotulska M.

Elektronika : konstrukcje, technologie, zastosowania

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2004

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Vol. 45, nr 8-9

130-132

EN

Pores of nanometer size created in a non-conducting membrane are considered as a new potential molecular sensor, which could be used for detection and characterization of single biomolecules. Especially biosensors for DNA detection and sequencing are in quest. The idea of molecular detection is based on the measurement of translocation time when a biomolecule is moving through the pore. This method could be extended with another approach - analysis of the nanopore slochastic characteristics, more appropriate for smaller molecules that do not block the pore.

PL

Pory o średnicy pojedynczych nanometrów, generowane w nie przewodzącej membranie, mogą być potencjalnie wykorzystane jako czujniki molekularne rozpoznające obecność i strukturę pojedynczych biomolekuł. Poszukiwane są zwłaszcza czujniki umożliwiające rozpoznawanie i sekwencjonowanie DNA. Najczęściej rozważane jest rozpoznawanie molekuł w oparciu o czas translokacji przez por. Metoda ta może być rozszerzona o analizę charakterystyki stochastycznej nanopora, która może dostarczyć więcej informacji w przypadku cząsteczek mniejszych, nie blokujących pora.