In the past, electronic engineering has been considered a purely male research field and, although this situation has changed slightly, the male prevalence in both academic and professional fields is ...still marked ...
The Internet of Things (IoT) is gaining more and more popularity and it is establishing itself in all areas, from industry to everyday life. Given its pervasiveness and considering the problems that ...afflict today's world, that must be carefully monitored and addressed to guarantee a future for the new generations, the sustainability of technological solutions must be a focal point in the activities of researchers in the field. Many of these solutions are based on flexible, printed or wearable electronics. The choice of materials therefore becomes fundamental, just as it is crucial to provide the necessary power supply in a green way. In this paper we want to analyze the state of the art of flexible electronics for the IoT, paying particular attention to the issue of sustainability. Furthermore, considerations will be made on how the skills required for the designers of such flexible circuits, the features required to the new design tools and the characterization of electronic circuits are changing.
The main requirement for using the Fluctuation Enhanced Sensing technique is the ability to perform low-frequency noise measurements. The portability of the measurement system is also a quite ...desirable feature not limited to this specific application. In this paper, an approach for the realization of a dual channel spectrum analyzer that is capable of exploring frequencies down to DC, although based on a USB sound card, is proposed. The lower frequency range of the input signals, which is outside the frequency range of the sound board, is upconverted to higher frequencies by means of a very simple modulation board. Then, the entire spectrum is reconstructed numerically by proper elaboration. With the exception of the modulation board, the approach we propose does not rely on any specific hardware. Thanks to the efficiency of the spectra estimation and reconstruction software, which is based on a public domain library, the system can be built on a low-cost computer single board computer, such as the Raspberry PI3. Moreover, when equipped with an optical TCP/IP link, it behaves as a compact spectrum analyzer that along with the device under test can be placed into a shielded environment, thus being isolated from external electromagnetic interferences.
We discuss the implementation challenges of gas sensing systems based on low-frequency noise measurements on chemoresistive sensors. Resistance fluctuations in various gas sensing materials, in a ...frequency range typically up to a few kHz, can enhance gas sensing by considering its intensity and the slope of power spectral density. The issues of low-frequency noise measurements in resistive gas sensors, specifically in two-dimensional materials exhibiting gas-sensing properties, are considered. We present measurement setups and noise-processing methods for gas detection. The chemoresistive sensors show various DC resistances requiring different flicker noise measurement approaches. Separate noise measurement setups are used for resistances up to a few hundred kΩ and for resistances with much higher values. Noise measurements in highly resistive materials (e.g., MoS
, WS
, and ZrS
) are prone to external interferences but can be modulated using temperature or light irradiation for enhanced sensing. Therefore, such materials are of considerable interest for gas sensing.
Electrochemical dissolution of metallic copper into slightly acidic aqueous solutions of chitosan yields a clear and stable dispersion of Copper Oxide nanoparticles into the organic polymer host. The ...electrochemically synthesized chitosan:CuOx nanocomposite is characterized by means of spectrophotometry, frequency domain electrical measurements and morphological analysis. Solid state electrochemical cells having pure chitosan as the electrolyte and using chitosan:CuOx as the electrode, are developed and characterized by means of electrical measurements performed in the ±1 V voltage window. The current-voltage loops of the cells, measured in deionized water, are found to reversibly change in response to hydrogen peroxide added to the water in 0.2 μM subsequent steps. Such changes, clearly distinguishable from changes recorded in response to other analytes, can be exploited in order to develop a hydrogen peroxide sensor able to work without the need for any supporting electrolyte.
Testing the shielding effectiveness of materials is a key step for many applications, from the industrial to the biomedical field. This task is very relevant for high-sensitivity sensors, whose ...performance can be greatly affected by electromagnetic fields. However, the available testing procedures often require expensive, bulky, and heavy measurement chambers. In this paper, a cost-effective and reliable measurement procedure for testing the shielding effectiveness of materials is proposed. It exploits a lab-scale anechoic shielded chamber, which is lightweight, compact, and cost-effective if compared to the available commercial solutions. The measurement procedure employs a vector network analyzer to allow an accurate and fast characterization setup. The chamber realization phases and the measurement procedure are described. The shielding capability of the chamber is measured up to 26 GHz, whereas the performance of commercial shielding coatings is tested to demonstrate the measurement’s effectiveness.
Ultra-High Temperature (UHT) pasteurized milk is the most diffused variety of milk in Europe. In this paper, a method is presented, employing Electrical Impedance Spectroscopy to characterize the ...different commercial milks commonly available in grocery stores and supermarkets. The curves of the measured admittance allow for the classification of the type of milk (whole, semi-skimmed, fat-free) and to distinguish lactose-free milk. An electrical circuit model has been derived and different values of circuit parameters add interesting information on the classification of the samples. Furthermore, the characterization allows for the identification of the degradation of the milk before it is visible to the eye, thus highlighting the difference between storage in the fridge and at room temperature, and identifying expired milk.
A conducting composite prepared by dispersing multi-walled carbon nanotubes (MWCNTs) into a host matrix consisting of Nafion, electrochemically doped with copper, has been prepared, characterized and ...used to modify one of the gold electrodes of simply designed electrochemical cells having copier grade transparency sheets as substrates. Electrical measurements performed in deionized water show that the Au/Nafion/Au-MWCNTs-Nafion:Cu cells can be successfully used in order to detect the presence of p-aminophenol (PAP) in water, without the need for any supporting electrolyte. The intensity of the redox peaks arising when PAP is added to deionized water is found to be linearly related to the analyte in the range from 0.2 to 1.6 µM, with a detection limit of 90 nM and a sensitivity of 7 µA·(µM(-1))·cm(-2).
Electrochemical devices using as substrates copier grade transparency sheets are developed by using ion conducting Nafion:polypyrrole mixtures, deposited between gold bottom electrodes and upper ...electrodes based on Multi Walled Carbon Nanotubes (MWCNTs). The electrical properties of the Nafion:polypyrrole blends and of the gold/Nafion:polypyrrole/MWCNTs devices are investigated under dry conditions and in deionized water by means of frequency dependent impedance measurements and time domain electrical characterization. According to current-voltage measurements carried out in deionized water, the steady state current forms cycles characterized by redox peaks, the intensity and position of which reversibly change in response to H2O2, with a lower detection limit in the micromolar range. The sensitivity that is obtained is comparable with that of other electrochemical sensors that however, unlike our devices, require supporting electrolytes.
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