Graphene, one of the recently discovered carbon nanostructures, has shown good piezoresistive properties. One of the most important areas of research for graphene sheets, in terms of basic science and application in strain or stress sensors, is the measurement of gauge factors. The gauge factors of various layers of graphene sheets are measured based on the equivalent stress beam. The measurement is carried out using a beam-bending method to detect the change in resistance of graphene sheets in different bending states. The gauge factor ranges from 10 to 15, depending on the number of layers in the graphene sheet. These results reveal the piezoresistance effect of single- and multi-layer graphene sheets, which will be of benefit in the fabrication of microsensors. The resistance of graphene sheets decreases as temperature increases from 20°C to 60°C, and the gauge factor is not very sensitive to changes in environmental temperature.
Electrolytic codeposition technique was adopted in the deposition of Ni-Fe-SiC composite coating on stainless steel
substrate, using nickel alloyed with iron as the binder phase with SiC as dispersed particles. The results indicated that the
deposit with SiC nanoparticles was level and compact; the
crystal-planes of the deposit were (111), (220) and (200). The
resistivity of deposit was about 30μΩ•cm. when the Fe(wt.%) ranged from 10% to 50% in the deposit, the electrodeposit
Ni-20%Fe-SiC has a strong paramagnetism effect with the smallest coercivity of 2.75×10-2 A/m. The remanence showed
a monotonic decrease with the increasing iron content in deposit. Which proved that the electroformed Ni-Fe-SiC alloy
has good electromagnetic property and higher corrosion resistance (with the corrosion rate 0.17 mg/dm2 per hour) than
those of electroforming Ni-Fe alloy. It is a promising material in the fabrication of micro actuator.
The relationship between the composition, coating
microstructure and electromagnetic properties of
electroforming Ni-Fe alloys was studied in this paper. And
the optimal process parameters to obtain Ni-20%Fe
deposition was as following: FeSO4·7H20 concentration was
6g/L; PH value of the solution was 2.5; current density was
3.5A/dm2; electrolyte temperature 55. The results indicate
that the Ni-Fe deposit is bright and compact, the crystalplanes
of the plating were (111), (220) and (200).
Electrodeposited Ni-20%Fe has a strong paramagnetism
effect with the smallest remanence of 0.5 emu, The
coercivity show a monotonic decrease with increasing Fe
content in deposit, and the saturation magnetization was
only 10% of that of the IJ85 permalloy, which proved that
the electroformed Ni-20%Fe alloy has good electromagnetic
property and could be used in MEMS actuator
manufacturing.
The field of micro electromechanical systems (MEMS), particularly micro sensors and transducers, has been expanding
over recent years, and the production of these devices continue to grow up. With SU-8 photoresist, the technology of
UV-LIGA has been developed as an important method of fabrication micro structures. The process consisting of
photolithographic and microelectroforming were studied in this paper. Orthogonal experimental design were applied in
research. From experiment it can be concluded that the soft bake temperature and time was the key factor of the structure
quality. When the photoresist thickness ranged from 120 to 340µm, the soft bake temperature and time was 90 and
50~120 minutes, that means the perfect image. The best post expose bake temperature was 85 95 with less 40
minutes bake. In order to obtain the suitable parameters of the various thickness photoresist, an artificial neural network
(ANN) with 3 layers were built. The ANN were trained based on orthogoality experiment using back propagation
algorithm. Compared to the experiment results, the prediction error was less than 2.0%, which proved that the ANN was
effective. The characteristics of the microelectroforming process were analysed systematically. The results showed that
the mass transfer is the control factors of microelectroforming process. During the developing of the photoresist,
ultrasonic stirring could shorten the developing time and improve the micro mould quality effectively.The lithographic
and microelectroforming process of the fabrication of high resolute micro structure was optimized.
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