Shi Yunbo

Synthesis of organic semiconductor hexadecachloro zinc phthalocyanine and its gas sensitivity

Due to the difficulty in synthesizing perhalogenated metallophthalocyanine, the method of ammonium molybdate solid phase catalysis was introduced, and by using tetrachlorophthalic anhydride and urea as the raw materials, hexadecachloro zinc phthalocyanine (ZnPcCl16) was synthesized. Components of the composite were analyzed by energy spectrum, and its functional group structures and absorption peaks were characterized by IR and UV-vis spectroscopy. The thin films of gas sensors were prepared in a vacuum evaporation system and evaporated onto SiO2 substrates, where sensing electrodes were made by MEMS micromachining. The optimal conditions for the films are: substrate temperature of 150 ◦ C evaporation current of 95 A and film thickness of 50 nm. The result showed that the sensors were ideally sensitive to Cl2 gas and could detect the minimum concentration of 0.3 ppm.

Design of Multi-parameter Wireless Sensor Network Monitoring System in Precision Agriculture

Precision Agriculture is an important direction of modern agriculture development, its main thought of technology is that we can acquire differences and space distribution through getting crops growth environment factors and growth conditions of ideal growing environment in time. We can analyze the reasons of the difference of crop yields and take effective control measures quickly. So this article designed a multi-parameter wireless monitoring system based on STM32F107 chip. The purpose was to monitor the parameters of the current crop growth environment. The hardware part of monitoring system was mainly divided into the optical path and electric circuit. The optical path structure refered to the system optical path part when using the test of soil organic matter content of the center wavelength of 850 nm near infrared light emitting diode (led), the incident and reflected light transmitting fiber and photoelectric diode. Circuit part mainly transmitted various environmental parameters of the signal to the minimum system for data processing and transmitted the data to PC for display and storage through the wireless communication mode. Experiment proved that this system could completely meet the daily precision agriculture for crop growth environment and the requirements of monitoring on the soil composition content, and the system had high reliability, the function was easy to extend.

Atmospheric PM2.5 Automatic Monitoring Gas Line System Design Based on Laser Scattering Method

This paper describes a semiconductor laser as the light source, Establish a real-time measurements optical system, with an particle number concentration of dust particles in the air. Gives a detailed structural principle of the system and how to use an optical sensor. According to Mie scattering theory, the light scattering characteristics of the response of the optical system. Experimental results show that the system has a high count accuracy, repeatability and counting efficiency for atmospheric PM2.5 monitoring.

Data mining research in wireless sensor network based on genetic BP algorithm

This paper associated the advantages of genetic and BP algorithm, and studied the application of genetic BP algorithm in wireless sensor network (WSN) data mining. It built a three-layer BP network based on the rapid random search ability of genetic and the mapping capability of BP algorithm, so the redundant history data in WSN could be mined and reused. The tests to 1000 groups of chlorine concentration data from chlorine gas sensor network had been conducted. And according to the comparison between predicted concentration and actual concentration, the maximum relative error was 11.8%, and the maximum average error was 6.96%. So the conclusion could be obtained that the algorithm model established by the paper is feasible and reliable under the condition of no explosive concentration leakage.

Sensitive properties of In-based compound semiconductor oxide to Cl2 gas

Aiming at detecting Cl2 gas, this study was made on how to make In-based compound semiconductor oxide gas sensor. The micro-property and sensitivity of In-based gas sensing material were analyzed and its gas sensitive mechanism was also discussed. Adopting constant temperature chemical coprecipitation, the compound oxides such as In–Nb, In–Cd and In–Mg were synthesized, respectively. The products were sintered at 600 °C and characterized by the Scanning Electron Microscope (SEM), showing the grain size almost about 50–60 nm. The test results show that the sensitivities of In–Nb, In–Cd and In–Mg materials under the concentration of 50 × 10−6 in Cl2 gas are above 100 times, 4 times and 10 times, respectively. The response time of In–Nb, In–Cd and In–Mg materials is about 30, 60 and 30 s, and the recovery time less than 2, 10 and 2 min, respectively. Among them, the In–Nb material was found to have a relatively high conductivity and ideal sensitivity to Cl2 gas, which showed rather good selectivity and stability, and could detect the minimum concentration of 0.5 × 10−6 with the sensitivity of 2.2, and the upper limit concentration of 500 × 10−6. The power loss of the device is around 220 mW under the heating voltage of 3 V.

Preparation of ZnO semiconductor formaldehyde gas sensor

Aimed at the current interior decoration formaldehyde pollution problems, through the analysis of the metal oxide semiconductor gas sensor characteristics and sensing mechanism, this paper combined with the influence of nanotechnology on sensor performance and designed semiconductor-type ZnO formaldehyde gas sensor. Prepared nano-ZnO using the sol-gel, doped H2PtCl6, La2O3 according to a certain proportion, sintered at 500°C for 3 hours and inorganic semiconductor sensitive material was compounded. By scanning electron microscopy (SEM) and differential thermal analyzer (DTA) the test results showed that the powder prepared was the nano-particle, the small particle size, and dispersion; sintering temperature was above 445°C. The sensor performance was test, the results showed that: the optimum operating voltage of the sensor was 4.8V, sensitivity was 5ppm, response time was 6s, detection range was 5-155ppm, and selectivity to alcohol, gasoline, carbon monoxide and other gases was high.

The fabrication of array wind speed and direction sensor based on Pt film

In order to meet the measurement requirements of the two-dimensional flow field in small-scale space, a new hot film wind speed and direction sensor based on Pt film is designed in this paper. The figure of array sensor is formed by magnetron sputtering and mechanical mask, whose process is simple and has good consistensy; the insulation groove is formed by micromachining technology, which can reduce the interaction between the heating elements and thermosensitive elements, so the power consumption is reduced, and the sensitivity is improved, the measurement of low wind speed is achieved.

Chlorine gas sensors using hybrid organic semiconductors of PANI/ZnPcCl16

PANI/ZnPcCl16 (polyaniline doped with sulfosalicylic acid/hexadecachloro zinc phthalocyanine) powders were vacuum co-deposited onto Si substrates, where Pt interdigitated electrodes were made by micromachining. The PANI/ZnPcCl16 films were characterized and analyzed by SEM, and the influencing factors on its intrinsic performance were analyzed and sensitivities of the sensors were investigated by exposure to chlorine (Cl2) gas. The results showed that powders prepared with a stoichiometric ratio of (ZnPcCl16)0.6(PANI)0.4 had a preferential sensitivity to Cl2 gas, superior to those prepared otherwise; the optimal vacuum co-deposition conditions for the films are a substrate temperature of 160 °C, an evaporation temperature of 425 °C and a film thickness of 75 nm; elevating the operation temperature (above 100 °C) or increasing the gas concentration (over 100 ppm) would improve the response characteristics, but there should be upper levels for each. Finally, the gas sensing mechanism of PANI/ZnPcCl16 films was also discussed.

Dust-concentration measurement based on Mie scattering of a laser beam

To realize automatic measurement of the concentration of dust particles in the air, a theory for dust concentration measurement was developed, and a system was designed to implement the dust concentration measurement method based on laser scattering. In the study, the principle of dust concentration detection using laser scattering is studied, and the detection basis of Mie scattering theory is determined. Through simulation, the influence of the incident laser wavelength, dust particle diameter, and refractive index of dust particles on the scattered light intensity distribution are obtained for determining the scattered light intensity curves of single suspended dust particles under different characteristic parameters. A genetic algorithm was used to study the inverse particle size distribution, and the reliability of the measurement system design is proven theoretically. The dust concentration detection system, which includes a laser system, computer circuitry, air flow system, and control system, was then implemented according to the parameters obtained from the theoretical analysis. The performance of the designed system was evaluated. Experimental results show that the system performance was stable and reliable, resulting in high-precision automatic dust concentration measurement with strong anti-interference ability.

Research in Automobile Exhaust Gas of Sulfur Dioxide and Nitrogen Dioxide Monitoring WSN and Optimization Coverage Algorithm

For help solving the air pollution problem caused by the mass increasing of Sulfur Dioxide And Nitrogen Dioxide automobile exhaust gas, we have designed a Zigbee wireless monitoring network to monitor the Sulfur Dioxide And Nitrogen Dioxide in automobile exhaust gas, and build this monitoring system in hardware and software. Also, we use a Artificial Fish Swarm Algorithm to optimize the network covering area. According to a simulation result, the network coverage could be increased to more than 95%, and it makes the network nodes more efficient, reduced the redundancy nodes, lower the system energy consumption, to meet the design qualification.