Papers by Keyword: Ethanol Sensor

Abstract: Ethanol sensor has been widely used in our daily life and industrial production, such as drunk driving test, food fermentation monitoring, and industrial gas leakage monitoring. With the advent of the Internet of Things (IoT) era, ethanol sensors will develop towards miniaturization and low-power consumption in the near future. However, traditional ethanol sensors with large volumes and high-power consumption are difficult to meet these requirements. Therefore, it is urgent to study ethanol gas sensors based on new materials and new structures. Here, we demonstrated a flexible ethanol sensor based on an ion gel-coated graphene field-effect transistor (IGFET). The device has a small graphene channel size with a width of 300 μm and a length of 200 μm. The device showed a low operating voltage of less than |±1| V. When the device was put into an ethanol gas condition, the Dirac point voltage of the IGFET showed a negative shift, which means an n-type doping effect to the graphene channel. Furthermore, the sensor showed a normalized current change of-11% against an ethanol gas concentration of 78.51 g/L at a constant drain-source voltage of 0.1 V. In addition, the device exhibited a fast response time of ~10 s and a recovery time of ~18 s. Moreover, the detectable range of the device was found to as wide as 19.76-785.1 g/L. Based on the above results, the flexible IGFET-based ethanol sensor with small size and low-power consumption has great potential to be used in the industrial production of the IoT era.

Abstract: An optimized study of tapered polymer optical fiber (POF) for measurement of different concentration of ethanol in deionized water (0.5%-3.5%) is proposed and demonstrated. This sensor operated based on evanescent wave absorption principle. The cladding of PMMA based POF is removed using organic solvents which can be used to create tapered POF. The unclad length around 1 cm and 3 cm as well as the waist diameters of POF in the range of 5 mm and 8 mm were compared for their efficiency as an ethanol sensor based on power output ratio values. Tapered POF with smaller waist diameter and longer tapered length showed higher sensitivity as ethanol sensor. Therefore, by tailoring the length and tapered diameter of POF, high sensitivity of ethanol sensor can be fabricated.

Abstract: Nanoparticles are considered unique sensing material as they are small and deliver sensitivity as low as parts per billion compared to their bulk counterparts used in the conventional devices. Zinc Oxide (ZnONPs) nanoparticles are considered one of the promising sensing materials due to their high surface-to-volume ratio compared to other conventional sensing materials. They have been found useful for sensing of hydrogen gas, carbon monoxide, ammonia and ethanol. Ethanol sensing forms a platform for monitoring various processes in medical and food industries. Herein, zinc oxide nanoparticles were synthesized using Spathodea campanulata plant extract as reducing and stabilizing agent. The biosynthesized nanoparticles were used to fine tuning a glassy carbon electrode (GCE) for ethanol sensing. Ethanol sensing capability of the modified GCE electrode was gauged upon its amperometric responses to different ethanol concentrations. The high surface to volume ratio of the nanoparticles greatly enhanced peak currents of the modified electrodes leading to signal towards ethanol detection.

Abstract: This paper presents the preparation of intensity-based plastic optical fiber (POF) sensor and its characteristics in the detection of ethanol concentration in water. Response of the sensor probes were analyzed for 0.02 to 1.00% v/v ethanol concentrations. The POF sensors have high sensitivity of detecting very low concentration of ethanol with 0.02% v/v ethanol in water. The reponsitivity of the polished U-shape sensor was 285 per percent of ethanol concentration. There are three distinct shapes of POF sensor probes that were developed: tapered U-shape; polished U-shape; and polished coil-shape. The POF were shaped into sensor probes by indirectly heating the POF at 80°C for several minutes and rapidly cooled in retaining the shapes. Tapering of POF was done using tensile tester with thermostatic chamber and other sensor probes were polished using fine abrasive for enhancing their sensitivities. The performance of the sensors was tested using He-Ne laser as the light source and the output spectra were analyzed using Ocean Optics spectrometer. The light intensity from the three sensors showed nonlinear response to ethanol concentrations from 0.02% - 1.00%. The POF sensor is more sensitive to 0.02%-0.10% ethanol concentration compared to 0.20% to 1.00%. At lower concentration, water tends to gradually absorb into POF polymer network and causes the fiber to swell more due to volume expansion. Higher ethanol concentration causes the swelling of the fiber to be eventually reduced and reached its detection limit.

Abstract: Coating with a calixarene derivative on gold surface of AT-cut quartz crystal, a piezoelectric quartz crystal (PQC) sensing device was successfully fabricated in this paper. Among four calixarene materials, the compound of MRCT was the most efficient actively coating material for recognizing ethanol molecule based on a host-guest recognition mechanism with C—H•••π interaction. In comparison with gas-chromatography (GC) method, the calixarene based PQC device can be well used for on-line detection of the ethanol vapor in the range of 0 ~ 3000 ppm around our environment with a recovery of 92.33~105.76 %. The detection limit can be evaluated to be 3.53 ppm. Furthermore, the proposed TSM sensor possessed good selectivity, reproducibility, reversibility and high stability for practical purpose.

Abstract: Urchin-like CuO, consisting of closely packed nanorods with a diameter of 10nm, have been successfully synthesized by a poly(ethylene glycol) (PEG)-assisted hydrothermal route at low temperature of 100°C. The as-obtained Urchin-like CuO were thoroughly characterized by X-ray diffraction (XRD) study, Field emission scanning electron microscope (FESEM), High-resolution transmission electron microscopy (HRTEM) and Gas sensor measurements. From the XRD pattern, all the peaks detected can be assigned to CuO in a monoclinic structure with lattice parameters a=4.662, b=3.416 and c=5.118 (JCPDS card no. 65-2309). The FESEM and TEM showed that the diameter of the urchin-like CuO sphere is about 1µm. Further investigation of the formation mechanism reveals that the PEG-assisted hydrothermal process is vital to the formation of 3D structures. Besides the template function, PEG often plays as a reductant while reacting with Cu(+2). In our case, no impurity peaks of Cu2O were observed in the XRD pattern, implying that PEG did not reduce Cu(+2) to Cu(+1). We attribute this to the high concentration of PEG. The sensor based on the urchin-like CuO nanostructures exhibit excellent ethanol-sensing properties at reduced working temperature (200°C), which shows a sensitivity two times higher than that of CuO particles(about 100nm, made from calcinations of Cu(NO3)2 at 400°C). The enhancement in sensitivity of the as-prepared CuO may be contributed to the fancy 3D nanostructures.

Abstract: ZnO nanostructures were synthesized by thermal oxidation reaction from zinc powder and then impregnated by gold colloid. The gold colloid was prepared by chemical reduction technique and had red color. The heating temperature and sintering time of thermal oxidation were 700 °C and 24 hours, respectively under oxygen atmosphere. The morphology of ZnO nanostructures and ZnO impregnated gold colloid were studied by field emission scanning electron microscope (FE-SEM). The diameter and length of pure ZnO and ZnO impregnated gold colloid were about the same value and were in the range of 100-500 nm and 2.0-7.0 µm, respectively. The ethanol sensing properties of ZnO impregnated by gold colloid were tested in ethanol atmosphere at ethanol concentrations of 1000 ppm and at an operating temperature of 260-360 °C. It was found that the sensitivity and response time were improved for gold impregnated sensor with an optimum operating temperature of 300°C due to the enhanced reaction between the ethanol and the adsorbed oxygen at an optimum temperature.

Abstract: Platinum impregnated ZnO tetrapods were prepared and studied for the detection of ethanol vapor. ZnO tetrapods were synthesized by oxidation reaction technique by heating a mixer of zinc powder (99.99%) and hydrogen peroxide solution (30 wt.%) at 1,000oC in air. Platinum was impregnated by dropping hydrogen hexachloroplatinate (IV) hydrate, H2Cl6Pt.aq, solution with different concentration on ZnO tetrapods and then, heated at 350oC for 1 hr. The platinum impregnated ZnO tetrapods were characterized by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS) for morphology and chemical composition, respectively. The particles were observed on the surface of ZnO tetrapods. The EDS spectrum suggested that the particles were platinum. Platinum impregnated ZnO tetrapods were tested ethanol sensing properties under ethanol concentration of 50-1,000 ppm. The ethanol sensing results indicated that the sensitivity of the sensors depended on the platinum impregnated concentration. Moreover, the sensors based on platinum impregnated ZnO tetrapods of 0.035 wt.% exhibited higher sensitivity compare to those of non-impregnation ZnO tetrapods.