Chou Xiujian

Synthesis of superparamagetic iron oxide nanoparticles in carbon reduction method

The current paper presents our new approach in synthesizing superparamagetic iron oxide nanoparticles. The Fe3O4 nanoparticles (~500nm) are synthesized through carbon reduction method, which is a brand new method. The best parameters of this method are fixed through characterizing transmission electron microscope (TEM), X-Ray Diffraction (XRD) and Vibrating Sample Magnetometer (VSM) of the Fe3O4 nanoparticles synthesized under different experimental conditions. The TEM characterization results show that the best ratio of the carbon and ferric chloride is 3:1 and the most suitable calcining time is 3 hours. The nanoparticles, which were obtained with furnace cooling under vacuum condition after 3 hours calcining, have the best magnetic properties and most stable crystal from. Moreover, the quantitative analysis of this new method is taken to confirm the repeatability of this method. The actual qualities of the Fe3O4 nanoparticles are always consistent with the theoretical one, which indicates that the repeatability of this method is excellent.

An integrated MEMS piezoresistive tri-axis accelerometer

An integrated MEMS accelerometer has been designed and fabricated. The device, which is based on the piezoresistive effect, accomplishes the detection of three components of acceleration by using piezoresistors to compose three Wheatstone bridges that are sensitive to the only given orientation. The fabrication of the accelerometer is described, and the theory behind its operation developed. Experimental results on sensitivity, cross-axis-coupling degree, and linearity are presented. The sensitivity of X, Y and Z were 5.49 mV/g, 5.12 mV/g and 4.82 mV/g, respectively; the nonlinearity of X, Y and Z were 0.01%, 0.04% and 0.01%, respectively; the cross-axis-coupling factor of X axis to Y axis and Z axis are 0.119% and 2.26%; the cross-axis-coupling factor of Y axis to X axis and Z axis are 0.157% and 4.12%; the cross-axis-coupling factor of Z axis to X axis and Y axis are 0.511% and 0.938%. The measured performance indexes attain accurate vector-detection in practical applications, and even at a navigation level. In conclusion, the accelerometer is a highly integrated sensor.