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Electronic nose (EN) can represent a useful tool in agrifood applications, thanks to its capability to identify meaningful parameters based on food-odor.This work is focused on the set up of a measurement protocol to track microbial contamination development in fish under environmental conditions by means of a miniaturized, fast, low-power consumption, EN based on two micro machined metal oxide gas sensors integrated into a USB controlled device. The sensors worked with custom temperature profile protocols and provided real time information.

Two phosphorous(V) corrole ligands, [5,10,15-pentafluorophenyl corrole] phosphorous (V), (PFCorr), and [10-(4-trimhetylsilyphenyl)-5,15-dimesityl-corrole] phosphorous (V) (PCorr) were synthesized and tested as nitrite-sensitive ionophore. Fluorimetry studies on ligand sensitivity towards anions were carried out first in solution and then inside polymeric membrane optodes. The selective ligand fluorescence quenching was registered upon addition of growing amount of NO 2 −-ions. The influence on the PFCorr optode response of the lipophilic sites functionalization was investigated. The sensor will be tested in natural (fresh and seawater) and fish farm waters in order to detect the effectiveness of nitrite assessment at recommended concentrations levels (less than 0.3 mg/L).

Breath analysis as well as the detection of abnormal respiratory rate can provide important feedback on people's health status. In this contribution we propose a wearable radiofrequency identification (RFID) epidermal device consisting of a flexible open loop antenna, that enables an easy adhesion on the user's skin, coupled with a graphene oxide-based sensor sensitive to the water vapour. The graphene oxide sensor was characterised in reference conditions, while the communication performance of the antenna was estimated by electromagnetic simulations over a human head phantom as well as by means of measurements on a volunteer. Finally, the whole system was experimentally demonstrated to be capable of comfortably detecting the inhalation/exhalation cycles and abnormal patterns of respiration like the apnea and tachypnea conditions by measuring the changes in graphene oxide resistance.

Atomic force microscopy is gaining interest as a technique to quantitatively study biological samples in native environment. However, the measuring principles behind may cause the presence of different sources of artifacts and image degradations. In this work, we present an AFM image analysis tool able to recognize morphological alterations in human leukemia cells after 3 h incubation with the antioxidant cerium oxide nanoparticles. To demonstrate the robustness of the approach to a particular artifact called contrast reversal (CR) effect, consisting in an unexpected switching between repulsive and attractive tip regime during scanning, we present a technique to artificially inject the artefact on the image and then apply the tool. Maximum area under the ROC (AUC) curve results of 0.91 (0.11) in the discrimination between exposed and unexposed cells confirm the validity of the approach and its applicability in AFM-based cell studies.

The monitoring of the breathing dynamic characteristics, including the presence of biomarkers in exhaled breath, is of growing interest in noninvasive diagnosis of diseases. We describe a wearable radiofrequency identification (RFID) device hosting a flexible antenna suitable for integration into a facemask and a sensor made of graphene oxide sensitive to the humidity variations. The so obtained wearable wireless sensor was characterized in reference conditions and was then experimentally demonstrated to be capable of detecting the inhalation/exhalation cycles and abnormal patterns of respiration like the apnea by measuring the changes in graphene oxide resistance.

Early stage asymmetric signs in breast that can be captured by the screening-digital mammography can be used for a precocious diagnosis of breast cancer. Conventional mammography screening fails to detect subtle anomalies, so computer-aided methods are studied in order to improve the accuracy of image analysis. To classify the images into asymmetric and normal cases, in this paper we investigated the performance of an Adaptive Artificial Immune System (A2INET) classifier. To test the efficiency of the algorithm, two public datasets have been considered: 32 pairs of mammographic images including MLO projection retrieved from Digital Database for Screening mammographic (DDSM) and 30 ones from Mammographic Image Analysis Society (mini-MIAS) databases. Results show that A2INET yields best results with respect to the other more conventional classifiers.

The sensitivity and the selectivity of metal-oxide gas sensors are largely dependent on the operating temperature. These sensors are usually operated either at a fixed temperature value or using a pattern of multiple temperatures. In either case, the temperature value and its profile have a predetermined unchangeable pattern. In this paper we propose an active temperature modulation methodology that gives rise to a self-adapted temperature pattern that can be used as a representative feature of the sensor response. For this purpose, we designed a closed-loop circuit, connecting the sensor resistance to the sensor heater. With this circuit topology deviations in sensor resistance value are mirrored into changes of operating temperature. Herewith, the method is implemented with an astable multivibrator, so with a steady resistance values the temperature modulation signal converges to a periodic pattern of pulses that is characteristic of the sensor state.

5,10,15,20-Tetraferrocenyl porphyrin (PFc4) and coumarin-based thia-aza macrocycle ligand (L3) were studied for the development of cross-sensitive optical chemical sensors aimed to the determination of transition metal ions. The ligands oppositely vary their fluorimetric response: PFc4 fluorescence is quenched upon the several transition metal ions concentration growth, while the fluorescence of L3 increases upon mercury ions exposure. By the simultaneous incorporation of both ligands in the same membrane, a series of cross-sensitive materials were obtained and tested for transition metal ions detection by CSPT method.

Passive UHF RFID tags, beside item labelling, are also able to exploit capability of sensing the physical state of the tagged object as well as of the surrounding environment. Here a family of polymer-doped tags are proposed and fully characterized for the detection of ambient humidity. A sensitive chemical species based on PEDOT:PSS is used to dope a properly shaped slot carved into a folded-like patch tag. The communication and sensing capabilities of the radio-sensor are investigated by means of simulation and measurements showing how to control and balance above opposite requirements by dosing the quantity of sensitive material. The device could have interesting application in the assessment of the air quality in living and controlled rooms, in the monitoring of the conservation state of foods, in the preservation of walls, and even to monitor the healing degree of wounds.

Porphyrins are versatile molecules that can serve as sensitive materials in many different kinds of chemical sensors. These properties greatly enhance when porphyrins are aggregated in nanostructured molecular assemblies. Among such structures, nanotubes are particularly interesting. In particular, the superior sensitivity of nanotubes was previously demonstrated with optical sensors. In this paper, we describe a nanotubular structure that enhances the porphyrin conductivity enabling the fabrication of porphyrin based chemoresistances.

Artificial olfaction systems have been investigated since more than two decades on alleged property of similarities between the receptive field of natural receptors and artificial sensors. Due to the limited number of sensors embedded in these systems the complexity of electronic noses is generally too low to allow the application of olfaction processing models. Actually the literature there are several models attempting to describe some olfaction functionalities, and the availability of an artificial platform to test models could be of great benefit for these studies. Recently, the use of optical image sensors has been demonstrated as a simple method to obtain large sensor arrays. Furthermore, an elegant and simple method to cluster individual sensors in classes allows for the definition of epithelium and glomerular layers. This system enables the application of a complex olfaction model, and these properties are here illustrated applying a glomerular compartmentalization model to the data generated by the exposure of such an artificial system to pure and mixed gases.

In this paper we propose a low single supply voltage (2V) analog lock-in amplifier, completely integrable on silicon, designed in a standard CMOS technology, for electronic sensor interfaces used in low-frequency applications. In particular, the proposed architecture is suitable for those sensor interfaces where the signal to be measured has a small amplitude and is buried into noise. In these cases, the lock-in amplifier guarantees the signal recovery from noise (till to 0.1 SNR), provided that the generated small signal, coming from sensor, has a fixed and well-known frequency. Together with the integrated solution, waiting for the chip fabrication, we have built a discrete element board, with commercial components, for preliminary experiments which confirm the validity of the proposed lock-in system, since it is able to detect, for example, very small quantities of carbon monoxide (CO).

Modern chemistry makes possibile the production of artificial receptors endowed with interaction sites specific towards selected analytes. To fabricate chemical sensors a transducer able to preserve the selectivity of such sensing layers is requested. We demonstrate the Field Effect Transistors (FET) coated by metalloporphyrins emphasizes the coordination of analytes with the sensing molecules with respect to the weakest forces that tend to cancel the selectivity. Molecular simulations show that coordination of gases such as carbon monoxide and nitric oxide greatly change the porphyrin electric dipole both in magnitude and direction inducing a large FET signal shift.

Nanostructured molecular assembly provides, in many cases, peculiar properties that are not found in the individual constituents. Among three-dimensional arrangements the tubular structures are particularly appealing for chemical sensor applications for expected surface increase and cavity effects. In this paper, the sensing properties of self-assembled nanotubes of oppositely charged porphyrins are investigated by measuring the changes of their optical properties. Computer screen photoassisted technology (CSPT) is utilized as a simple and practice platform to test the optical sensitivity of sensing materials and to develop chemical sensing systems.

Nanostructured molecular assembly provides, in many cases, peculiar properties that are not found in the individual constituents. Among three-dimensional arrangements the tubular structures are particularly appealing for chemical sensor applications at least for the expected surface increase. In this paper, the sensing properties of nanotubes self-assembled of oppositely charged porphyrins are investigated for the first time. Nanotube arrangement is shown to increase the sensitivity in both mass and optical sensors. The optical sensitivity, not found in individual porphyrins, appears as an intrinsic nanotube property.

Metalloporphyrins shown interesting properties as sensitive material for chemical sensors. In particular, they shown brilliant behaviours in electronic nose applications. From the point of view of this kind of applications it is necessary to differentiate sensor selectivity. In this paper, a method to enhance the selectivity of metalloporphyrins to hydrogen bond interacting compounds is illustrated. Furthermore, the structural modification of metalloporphyrin results in highly porous spatial arrangement of molecular films. This feature produces an improvement also at sensor sensitivity level. Modified metalloporphyrins were used to coat thickness shear mode resonators. The sensors were tested to different gases and results confirmend the enhanced responses to hydrogen bond interacting compounds such as alcohols.

Different strategies for the dynamical calibration of gas sensors have been applied to Quartz Microbalance polymer coated sensors exposed to binary mixtures of Toluene and Octane. White Gaussian Noise and steps signals are used for calibration and validation purposes. This work is the first attempt to a comparative analysis of diverse methods in gas sensor dynamic calibration.

The oxygen transport in blood is threatened by the presence of carbon monoxide. CO indeed permanently replaces the oxygen molecule in the hemoglobin making this last no more effective as oxygen carrier. This mechanism is ruled by the properties of a particular metalloporphyrin (heme) for which the binding energy with CO is about 250 times higher than that towards O/sub 2/. In this paper, a sensor system based on the properties of metallaporphyrins with a colorimetric read-out is illustrated. This system is shown to be sensitive both to the concentration of CO and to the exposure time giving rise to the evaluation of the biological damage of carbon monoxide. Results shown a good accuracy of the carboxy-hemoglobin (HbCO) percentage, calculated with a standard reference model, achieving a standard error of 1%. This value is well below the amount of HbCO known to produce either acute or chronic effects on human beings.

Heavily p-doped monocrystalline silicon wires have been fabricated by employing wet etch and thermal oxidation steps to achieve a nanometric cross-section; a gate oxide growth and a final palladium evaporation made up the MOS junction able to detect hydrogen concentrations in air.

Arrays of chemical sensors are affected by different disturbances. They are due, in part to the environment and in part to the non-ideality of the system. Since sensors cannot be completely insulated from the surrounding environment the fluctuation of ambient parameters (e.g. temperature and relative humidity) may be so large to strongly limit the resolution of the sensor array. In this work, Independent Component Analysis (ICA) are introduced as a preprocessing method aimed at reducing the influence of spurious disturbances on the meaningful part of the data. The method is shown on a practical experiment aimed at distinguishing the ripeness stage of apples measured at different room temperatures and relative humidity. The benefits in term of improved classification will be illustrated and discussed.

An electronic nose is now becoming available as a commercial product. Nevertheless its performances are not fully understood and interpreted. Also the differences between electronic noses and the human olfaction have not yet been sufficiently studied. This is an important issue in many industrial sectors, such as food analysis. In this paper a comparison between the performances of an electronic nose and a panel of human tasters is presented in a selected case (tomato paste). An extensive set of tools for data analysis was available. A number of chemometrics based methods (principal component analysis and cluster analysis) and neural networks (feedforward backpropagation trained networks, self organizing maps, adaptive resonance theory based networks) have been utilized to analyze electronic nose data in order to extract the relevant information. The electronic nose and the human panel show strong similarities but the former displays a more concise classification capability for the data.