A Method for Measuring Thermal Conductivity of Low-Dimensional Materials Based on DC Heating

Due to the small size of low-dimensional materials, traditional experimental methods can hardly meet the requirements of accurate measurement. This paper presented a method for measuring the thermal conductivity of low-dimensional materials based on DC heating. This method adopted a micro-machining process to prepare a measuring electrode in advance, and only needed to suspend the object (one-dimensional wire or two-dimensional film) on the electrodes and maintain close contact. Finally, a standard diameter of 20 μm platinum wire was used to verify the measurement accuracy of this method. The application and future development of thermal conductivity testing structures for low-dimensional materials were also prospected.

Diseño y monitoreo en tiempo real de un biodigestor, aplicado a las condiciones ambientales de Hermosillo

The general objective of this research is to sense and monitor the main variables that affect biodigestion processes; temperature, hydrogen potential (pH), humidity, volume and pressure within the bioreactor, and correlate them with the production of biogas, through a real-time monitoring system. For the development of the system design, information was collected on the variables and factors that affect the biodigestion process. Subsequently, the instruments and integral elements of the monitoring and sensing system were selected, all these electronic devices for commercial use and mentioned below. An LM35 sensor for temperature measurement, an industrial analog type measuring electrode for pH measurement, an FC-28 for moisture measurement, an MQ2 electrochemical sensor for measurement of methane production, an HC-SR04 ultrasonic sensor for level measurement (related to the volume of the biodigester) and a piezoelectric sensor MPX2202DP case 344C-01 for pressure measurement. The values captured by the sensors will be displayed in real time in a Visual Studio application, and will be automatically saved in a database. The integration of the system was experimentally tested in a span of 12 days in the city of Hermosillo, Sonora, Mexico, where measurements were obtained for comparison with other authors.

Structure Optimization of a New Micro-Hotplate Designed for Gas Sensor

Thepaperpresents the design of a new micro-hotplate.Useplatinum filament as electrode material, Si and SiO2assubstrate materials.Through the structure optimizing analysis, the micro-hotplate owns the best temperature distribution, when the thickness of Si, the front and rear SiO2are set to 125, 25 and 150 μmrespectively, the width of heating electrode is 50μm and the measuring electrode is withoutinterdigital electrode. The new micro-hotplate is benefit for the improvement of sensitivity and overall performance of the sensor.