Selective acetone electrical detection using functionalized nano-porous silicon
01 Dec 2015-pp 1-4
TL;DR: In this article, a functionalized nano-porous silicon (PS) was used for detecting acetone in the presence of volatile organic compounds (VOCs) and moisture.
Abstract: This paper reports selective acetone sensing portrayed by functionalized nano-porous silicon (PS). Functionalization of nanostructure was performed using hexamethyldisilazane (HMDS). Nano-PS fabrication and morphology analysis were done using electrochemical etching and SEM respectively. Optical properties of PS were analyzed using Raman and Photoluminescence (PL) spectroscopy. Parallel aluminium electrodes were formed on nano-PS surface using thermal evaporation technique. These electrodes were used for recording electrical measurements from porous surface in presence of volatile organic compounds (VOCs) and moisture. Resistance variations due to interaction of sensing surface with different concentrations of ethanol, acetone, moisture and isopropyl alcohol vapors were monitored at room temperature. Various sensor parameters were calculated like sensitivity, response- and recovery-time. Sensor based on functionalized nano-PS was found to be most responsive for acetone in comparison to other VOCs or moisture. Since, acetone is one of the important metabolite components in the circulated blood of the human body therefore, its concentration determination is necessary. The approach for selective sensing presented in this work is simple and low cost.
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TL;DR: In this paper, a relaxation in the q-vector selection rule for the excitation of the Raman active optical phonons was proposed to increase the red shift and broadening of the signal from microcrystalline silicon films.
Abstract: The red shift and the broadening of the Raman signal from microcrystalline silicon films is described in terms of a relaxation in the q-vector selection rule for the excitation of the Raman active optical phonons. The relationship between width and shift calculated from the known dispersion relation in c-Si is in good agreement with available data. An increase in the decay rate of the optical phonons predicted on the basis of the same model is confirmed experimentally.
105 citations
TL;DR: This article provides a comprehensive study on the state of the art research activities in gas sensor field, mainly focuses on the metal oxide semiconductor based acetone sensors such as WO3, ZnO, SnO2, Sno2, Fe2O3), which are used for metabolic monitoring and breath analyzing.
Abstract: Finding a non-invasive, painless and simple method for monitoring of health parameters and early detection of physiological disorders is of utmost importance in today’s world. Breath analysis has been attracted tremendous attention as a potentially powerful tool for studying the medical diagnosis diseases because of its noninvasive nature and capability of real-time monitoring. For metabolic monitoring, several candidates are attractive. As an example, acetone has been considered as a main breath biomarker for diabetes. In addition to diabetes, fat burn monitoring is another application for breath acetone. This article provides a comprehensive study on the state of the art research activities in gas sensor field. It mainly focuses on the metal oxide semiconductor based acetone sensors such as WO3, ZnO, SnO2, Fe2O3, In2O3, TiO2, Co2O3, NiO and etc. Several different type of acetone sensor technologies such as polymer based chemiresistors, mixed potential, optical and mass sensitive devices are presented as well. The effect of nano structures and morphology on response of sensors are discussed. The advantages and disadvantages of different techniques used for metal oxide semiconductor synthesis are also discussed. Finally, sensor arrays with different receptor materials and transducers for breath analyzing are discussed.
64 citations
Cites background from "Selective acetone electrical detect..."
...Although this review highlights metal oxides and polymer based chemiresistor for acetone detection, other materials such as graphene [266], functionalized gold and platinum nanoparticle [267], phthalocyanine film [268], functionalized nano-porous silicon [269] and etc....
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TL;DR: In this paper, a miniaturized prototype sensor based on TiO2 nanotubes/porous silicon (PS) heterojunction is developed for selective ethanol sensing in sub-ppm range.
Abstract: A miniaturized prototype sensor based on TiO2 nanotubes/porous silicon (PS) heterojunction is developed for selective ethanol sensing in sub-ppm range. Titanium (Ti) of thickness ∼ 200 nm was deposited on PS using RF sputtering technique. Both silicon and Ti were sequentially anodized to form PS and nanotubes respectively. Electrical contacts for testing of resistive sensors were fabricated using lift off process. The sensor was packaged onto a 12-pin header and tested in presence of different VOCs with concentration ranging from 0.5 to 100 ppm. The selective ethanol sensing at around 150 °C stems from the formation of TiO2 nanotubes/PS heterojunction. The sensitivity of such a sensor, improved manifold in comparison to the response of pure PS and pure TiO2 based sensors. The formation of heterojunction, selective response to ethanol, sub-ppm level sensing at comparatively low operating temperature is discussed. The study unfolds the collective properties of TiO2/PS heterojunction and demonstrates the potential of wafer scale integrated repeatable ethanol sensor tested at sub-ppm level.
44 citations
TL;DR: In this article, the synthesis of orthorhombic (α) MoO3 nano-flakes by dry oxidation of RF sputtered Mo thin film is presented, where the influence of Mo thickness variation, oxidation temperature and time on the crystallographic structure, surface morphology and roughness of MoO 3 thin films was studied using SEM, AFM, XRD and Raman spectroscopy.
Abstract: Synthesis of orthorhombic (α) MoO3 nano-flakes by dry oxidation of RF sputtered Mo thin film is presented. The influence of Mo thickness variation, oxidation temperature and time on the crystallographic structure, surface morphology and roughness of MoO3 thin films was studied using SEM, AFM, XRD and Raman spectroscopy. A structural study shows that MoO3 is polycrystalline in nature with an α phase. It was noticed that oxidation temperature plays an important role in the formation of nano-flakes. The synthesis technique proposed is simple and suitable for large scale productions. The synthesis parameters were optimized for the fabrication of sensors. Chrome gold-based IDE (interdigitated electrodes) structures were patterned for the electrical detection of organic vapors. Sensors were exposed to wide range 5–100 ppm of organic vapors like ethanol, acetone, IPA (isopropanol alcohol) and water vapors. α-MoO3 nano-flakes have demonstrated selective sensing to acetone in the range of 10–100 ppm at 150 °C. The morphology of such nanostructures has potential in applications such as sensor devices due to their high surface area and thermal stability.
32 citations
TL;DR: In this paper, the surface treatment of porous silicon (PSi) for enhancing the sensitivity of water vapors at room temperature was highlighted, where spin coated polyvinyl alcohol (PVA) was used for functionalizing PSi surface.
5 citations
References
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TL;DR: In this article, a capacitive humidity sensor with a porous silicon (PS) dielectric and electronics is presented, where the adsorption of water vapor by the PS layer leading to change of its effective Dielectric constant is modeled with an effective medium approximation (EMA).
Abstract: A novel hygrometer is presented, comprising a capacitive humidity sensor with a porous silicon (PS) dielectric and electronics. The adsorption of water vapor by the PS layer leading to change of its effective dielectric constant is modeled with an effective medium approximation (EMA). A simple, but precise, phase-sensitive electronic circuit has been developed. This detects any change of phase of a sinusoidal signal transmitted through the PS dielectric and correlates to ambient humidity. It is outlined how the nonlinear response of the sensor is compensated through piecewise linearization. The sensor is tested in combination with the phase detection circuitry. Excellent linearity over the entire range of relative humidity is achieved. Experimental results show a resolution better than 0.1% and an accuracy of 2% (near the transition region) and better than 0.1% (otherwise). The response time is less than 10 s with good stability.
47 citations
"Selective acetone electrical detect..." refers background in this paper
...00 ©2015 IEEE environmental [8] , enzyme detection [9] and a PS exclusion matrix based on different pore sizes for sensing of organic molecules [10-11]....
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TL;DR: In this article, the sensor parameters were studied for organic vapours like methanol, ethanol, propanol, acetone and benzene at low ppm level using capacitive measurements and a probabilistic approach of the concentration dependent vapour molecular kinetics was demonstrated to explain the sensor performance and selectivity studies.
Abstract: Porous silicon (PS) samples were prepared under different anodization conditions and correspondingly the sensor parameters were studied for organic vapours like methanol, ethanol, propanol, acetone and benzene at low ppm level using capacitive measurements. The surface morphology of the samples was characterized by scanning electron microscopy (SEM), whereas Raman spectroscopic studies were made to identify the surface species formed due to surface passivation. Selective response was observed for either methanol or ethanol depending on the combined effect of the pore morphology of PS, its surface passivation and the concentration dependent molecular kinetics in vapour phase. A probabilistic approach of the concentration dependent vapour molecular kinetics is demonstrated to explain the sensor performance and selectivity studies.
30 citations
01 Oct 2006
TL;DR: In this article, nanowires of conducting polypyrrole (PPy) were synthesized by chemical polymerization methode and the reaction was carried out for three different times (6 h, 24 h, 40 h) and reaction rate was 200 rpm.
Abstract: Nanowires of conducting polypyrrole (PPy) were synthesized by chemical polymerization methode. The 0.18 mol of pyrrole (Py) as monomer, 0.18 mol of dodecyl-benzene sulfonic acid (DBSA) as dopant and 0.26 mol of anhydrous iron(lll) tri chloride (FeCl3) as oxidant were mixed and stirred in 200 ml of distilled water at 0degC. The reaction was carried out for three different times (6 h, 24 h, 40 h) and reaction rate was 200 rpm. The morphology of PPy was evaluated by field emission scanning electron microscopy (FE-SEM). It was found that the morphology of nanowire PPy was affected by reaction time and aggregation rate. When the polymerization time was getting longer, nanowire structure was appeared clearly. The sensitivities of nanowire PPy were investigated with volatile organic compounds (VOCs).
11 citations
TL;DR: In this article, the authors describe the characterization and optimization of anisotropic formation of porous silicon in large volumes (0.5?1 mm3) of silicon by an electroless wet etching technique.
Abstract: This work describes the characterization and optimization of anisotropic formation of porous silicon in large volumes (0.5?1 mm3) of silicon by an electroless wet etching technique. The main goal is to use porous silicon as a sacrificial volume for bulk micromachining processes, especially in cases where etching of the full wafer thickness is needed. The porous silicon volume is formed by a metal-assisted etching in a wet chemical solution composed of hydrogen peroxide (30%), hydrofluoric acid (40%) and ethanol. This paper focuses on optimizing the etching conditions in terms of maximizing the etching rate and reproducibility of the etching. In addition to that, a study of the morphology of the pore that is obtained by this technique is presented. The results from the characterization of the process are applied to the fabrication of boron?silica?glass cantilevers that serve as a platform for bio-chemical sensors. The porous silicon volume is formed in an early step of the fabrication process, allowing easy handling of the wafer during all of the micromachining processes in the process flow. In the final process step, the porous silicon is quickly etched by immersing the wafer in a KOH solution.
8 citations
"Selective acetone electrical detect..." refers background in this paper
...This can cause or aggravate disease 50 such as allergies, asthma, cancer, and emphysema [4-5] ....
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