The demand for reliable devices to detect tumor biomarkers in human body is constantlyincreasing [...]
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Nowadays, most medical-diagnostic, environmental monitoring, etc. devices employ sensors whose fabrication reproducibility and response repeatability assessment are crucial. The former consists of large-scale sensor manufacture through a... more
Nowadays, most medical-diagnostic, environmental monitoring, etc. devices employ sensors whose fabrication reproducibility and response repeatability assessment are crucial. The former consists of large-scale sensor manufacture through a standardized process with almost identical morphology and behavior, while the latter consists of giving the same response upon repeating the same stimulus. The thermo-activated chemoresistive sensors, which change their conductance by interacting with the molecules composing the surrounding gas, are currently employed in many devices: in particular, thick-film (SnTiNb)O2 nanosensors were demonstrated to be particularly suitable in the medical and biological fields. Therefore, a set of thirteen of them, randomly selected from the same screen-printing deposition, were laboratory tested, and the outcomes were statistically analyzed in order to assess their consistency. At first, the working temperature that maximized both the sensor sensitivity and res...
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Chemoresistive nanostructured gas sensors are employed in many diverse applications in the medical, industrial, environmental, etc. fields; therefore, it is crucial to have a device that is able to quickly calibrate and characterize them.... more
Chemoresistive nanostructured gas sensors are employed in many diverse applications in the medical, industrial, environmental, etc. fields; therefore, it is crucial to have a device that is able to quickly calibrate and characterize them. To this aim, a portable, user-friendly device designed to easily calibrate a sensor in laboratory and/or on field is introduced here. The device comprises a small hermetically sealed chamber (containing the sensor socket and a temperature/humidity sensor), a pneumatic system, and a custom electronics controlled by a Raspberry Pi 4 developing board, running a custom software (Version 1.0) whose user interface is accessed via a multitouch-screen. This device automatically characterizes the sensor heater in order to precisely set the desired working temperature, it acquires and plots the sensor current-to-voltage and Arrhenius relationships on the touch screen, and it can record the sensor responses to different gases and environments. These tests wer...
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ABSTRACT In this work we report the synthesis, microstructure, electric and spectroscopic properties, and sensing performances of TixSn1−xO2 (x=0.1, 0.2, 0.3, 0.5, 0.7, 0.9) nano-powders and of SnO2 and TiO2 reference samples, prepared... more
ABSTRACT In this work we report the synthesis, microstructure, electric and spectroscopic properties, and sensing performances of TixSn1−xO2 (x=0.1, 0.2, 0.3, 0.5, 0.7, 0.9) nano-powders and of SnO2 and TiO2 reference samples, prepared via sol-gel route starting from metal-organic precursors working in hydro-alcoholic media. Actually, the attention is particularly focused on properties of the sample with x=0.2, in comparison with ones of the other solid solutions and of the single oxides. Indeed, this solid solution showed a borderline behaviour between that of the solid solution with x=0.1 and that of the other solid solutions with x≥0.3. An abrupt change in the structural, electrical and spectroscopic properties has been observed, passing from sample with x=0.1, showing a behaviour very similar to that of SnO2, to one x=0.3 showing a behaviour very similar to that of TiO2. The borderline properties of the mixed oxide with x=0.2 represent the expected continuous transition among the two behaviours.
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ABSTRACT Metal-oxide semiconductors are widely used as functional materials for gas sensing because of their chemoresistive effect when interacting with ambient gases. For this work, nanosized TixSn1−xO2 have been synthesized at... more
ABSTRACT Metal-oxide semiconductors are widely used as functional materials for gas sensing because of their chemoresistive effect when interacting with ambient gases. For this work, nanosized TixSn1−xO2 have been synthesized at increasing Ti molar ratio (x = 0, 0.1, 0.2, 0.25, 0.3, 0.5, 0.7, 0.8, 0.9, 0.95, 1) and extensively investigated through a wide variety of characterizations. It turned out that the merging process of the two single oxides formed new compounds with improved gas responses compared to pure TiO2 and also to pure SnO2. Moreover, all investigated physico-chemical characteristics resulted tuneable through the titanium content in the solid solution. Each characterization carried out onto TixSn1−xO2 solid solutions made it possible to identify two classes of materials with SnO2-like or TiO2-like behaviours, the best CO response being on the intersection of the two species of materials. Moreover, a very interesting analysis on the generally accepted electrical transport model through polycrystalline semiconductors has been carried out. Indeed, the comparison with experimental evidences has highlighted a conduction mechanism not previously considered.
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... View Within Article. Schottky barrier, S b , measurements were performed with the thermal stimulated current technique as described in Ref. [6]. Accordingly, the samples underwent a thermal cycle from 100 to 500 °C and back to obtain... more
... View Within Article. Schottky barrier, S b , measurements were performed with the thermal stimulated current technique as described in Ref. [6]. Accordingly, the samples underwent a thermal cycle from 100 to 500 °C and back to obtain the inverse-temperature Ahrrenius plot. ...
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... Author , a , Matteo Ferroni a , Sandro Gherardi a , Vincenzo Guidi a , Cesare Malagù a , Giuliano Martinelli a , Michele Sacerdoti b , Maria Luisa ... 2. G. Martinelli, MC Carotta, E. Traversa and G.Ghiotti, Thick film microsensors... more
... Author , a , Matteo Ferroni a , Sandro Gherardi a , Vincenzo Guidi a , Cesare Malagù a , Giuliano Martinelli a , Michele Sacerdoti b , Maria Luisa ... 2. G. Martinelli, MC Carotta, E. Traversa and G.Ghiotti, Thick film microsensors based on nano-sized semiconducting oxide powders. ...
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Abstract Humidity is always present in real applications of semiconductor gas sensors, e.g. in the environmental monitoring or medical applications, therefore it is important to study the effects that water vapor has on sensors... more
Abstract Humidity is always present in real applications of semiconductor gas sensors, e.g. in the environmental monitoring or medical applications, therefore it is important to study the effects that water vapor has on sensors conduction. This work is a study of the humidity role in the conduction mechanisms of two sensor materials: tin oxide (SnO2) and a mixture of tin, titanium and niobium oxide (STN), showing the property of the second of being less affected by humidity, therefore useful in medical and environmental applications. Laboratory and on-field tests have been performed with water vapor and CO, at different concentration, initial conditions and partial pressures, both singularly and in combination. A novel concept of sensitivity is introduced in this work, called two-dimensional sensitivity, which not only quantifies the dependence of sensors response on the concentration of the analyte, but also on the variation of humidity and their non-linear combination. By taking the partial derivative of the fitting function with respect to CO concentration, it is possible to gather not only information about the dependence of the signal variation on the gas concentration, but also how it is influenced by water vapour, even when the water vapor partial pressure is kept constant, and vice versa.
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Graphene oxide has been functionalized with 1-aza-15-crown-5 ether via chemical route synthesis. Modification of graphene oxide was achieved via nucleophilic attack where the amine groups of an aza-crown ether molecule can easily react... more
Graphene oxide has been functionalized with 1-aza-15-crown-5 ether via chemical route synthesis. Modification of graphene oxide was achieved via nucleophilic attack where the amine groups of an aza-crown ether molecule can easily react with the epoxy sites of graphene oxide basal plane. Owing to the inherent two-dimensional character of graphene oxide, it resulted in large specific-surface material with strong affinity for charged chemical species. Such property was exploited for reversible and controlled interaction of adsorbed species, envisaging two possible applications of the functionalized graphene oxide. Thus, an easy-to-fabricate and high-sensitivity functionalized graphene oxide-based gas sensor was achieved. The sensing material proved to be highly stable and capable of selectively detecting humidity at room temperature over a wide range of concentrations. Moreover, the porous scaffold built by the functionalization, together with the well-known affinity of crown ethers to metal ions, allow the use of aza-crown ether functionalized graphene oxide for cation trapping application, e.g. pre-concentration of trace amount of metals or filter for water. Remarkable results in this field have been obtained with respect to some heavy-metal cations of environmental interest.Wealso demonstrated significant enhancement in performance versus pure graphene oxide in both tested applications. More generally, the functionalization approach we pursued appears to be quite flexible in the tested applications. In fact, with an appropriate selection of crown ethers with specific cage-like structure, functionalized graphene oxide allows the capture of any desired guest in order to prepare a wide range of other crown-ether-GO nanocomposites for different applications
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Abstract Colorectal cancer is one of the widely diffused tumors. Despite its high curable rate, if diagnosed in its polyp state, an efficient screening method is highly desirable for preventing and decreasing deaths. Tumor biomarkers,... more
Abstract Colorectal cancer is one of the widely diffused tumors. Despite its high curable rate, if diagnosed in its polyp state, an efficient screening method is highly desirable for preventing and decreasing deaths. Tumor biomarkers, emitted by the peroxidation of the cell membrane, may alter the composition of feces. We developed an array of chemoresistive sensors (both metal oxides and sulfides) capable of distinguishing between real stool samples of healthy subjects and of patients with colorectal cancer at diverse degeneration stages. Preliminary clinical validation of real samples was carried out. Results have shown the selectivity of the sensor array towards tumor affected and healthy subject samples. A quadratic discriminant analysis was performed, with a classification error of about 5%.
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Introduction Recently, great attention has been paid to solid solutions and composite materials based on metal oxides in order to obtain nanostructures with enhanced sensing performance with respect to those of single-oxide counterparts... more
Introduction Recently, great attention has been paid to solid solutions and composite materials based on metal oxides in order to obtain nanostructures with enhanced sensing performance with respect to those of single-oxide counterparts [1]. Tin and titanium dioxides (SnO2 and TiO2) are wide-gap n-type semiconductors extensively investigated for the fabrication of solid-state devices for gas sensing applications. Albeit SnO2-based gas sensors exhibit high response to reducing gases, they suffer of poor selectivity and degradation of electrical properties at low oxygen partial pressure and high operating temperatures upon prolonged exposure to reducing gases [2]. Instead, TiO2 is more thermally stable than SnO2, but it has a lower sensitivity due to a higher density of surface states, that entails the pinning of the Fermi level [3]. SnO2 and TiO2 would easily form solid solutions because they can exhibit a rutile type structure where octahedrally coordinated Ti4+ and Sn4+ have simila...
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Early-stage tumor detection is one of the most coveted goals for the world research community. An effective prevention, associated to reliable screening protocols, is crucial to favor a early diagnosis, allowing doctors and surgeons to... more
Early-stage tumor detection is one of the most coveted goals for the world research community. An effective prevention, associated to reliable screening protocols, is crucial to favor a early diagnosis, allowing doctors and surgeons to intervene with high probabilities of success on tumor affected patients. The main purpose of this study is cancer detection, exploiting the volatile organic compounds (VOCs) produced by cancer cells as tumor biomarkers [1][2], by investigating tumor tissue and blood samples. Tumor biomarkers exhalation is attributed to two main cell involving biological mechanisms: altered metabolism and cellular membrane peroxidation [3]. This experimental work was carried on using an innovative, fast-responding and reliable patented device, named SCENT B1 [4], entirely designed and assembled in the Sensor Laboratory of the University of Ferrara. It hosts an array of four specific metal-oxide (MOX) sensors able to detect gases in low concentration (up to 10 ppm) with...
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Dispositivo portatile di monitoraggio, di semplice utilizzo ed a basso costo. Esso costituirà una forma di pre-analisi nell’ambito della diagnostica del cancro al colon-retto (CCR) sin dallo stadio di adenoma, composto da un sistema... more
Dispositivo portatile di monitoraggio, di semplice utilizzo ed a basso costo. Esso costituirà una forma di pre-analisi nell’ambito della diagnostica del cancro al colon-retto (CCR) sin dallo stadio di adenoma, composto da un sistema pneumatico e da un array di sensori a stato solido per gas, capaci di rivelare i VOC biomarcatori della suddetta patologia, emessi da un campione di feci. Tale misura, analizzata in seguito mediante uno specifico algoritmo, fornirà l’esito negativo o positivo della diagnosi