An integrated micro positioning xy-stage with a 2mm × 2mm-area shuttle is fabricated for application in nano- meter-scale operation and nanometric positioning precision. It is mainly composed of a silicon-based x...An integrated micro positioning xy-stage with a 2mm × 2mm-area shuttle is fabricated for application in nano- meter-scale operation and nanometric positioning precision. It is mainly composed of a silicon-based xy-stage,electrostatics comb actuator,and a displacement sensor based on a vertical sidewall surface piezoresistor. They are all in a monolithic chip and developed using double-sided bulk-micromachining technology. The high-aspect-ratio comb-driven xy-stage is achieved by deep reactive ion etching （DRIE） in both sides of the wafer. The detecting piezoresistor is located at the vertical sidewall surface of the detecting beam to improve the sensitivity and displacement resolution of the piezoresistive sensors using the DRIE technology combined with the ion implantation technology. The experimental results verify the integrated micro positioning xy-stage design including the micro xy-stage, electrostatics comb actuator,and the vertical sidewall surface piezoresistor technique. The sensitivity of the fabricated piezoresistive sensors is better than 1.17mV/μm without amplification and the linearity is better than 0. 814%. Under 30V driving voltage, a ± 10vm single-axis displacement is measured without crosstalk and the resonant frequency is measured at 983Hz in air.展开更多
Isolation and purification of single-walled carbon nanotubes （SWCNTs） are prerequisites for their implementation in various applications. In this work, we present a fast （-5 min）, low-cost, and easily scalable ben...Isolation and purification of single-walled carbon nanotubes （SWCNTs） are prerequisites for their implementation in various applications. In this work, we present a fast （-5 min）, low-cost, and easily scalable bench-top approach to the extraction of high-quality isolated SWCNTs from bundles and impurities in an aqueous dispersion. The extraction procedure, based on aqueous two-phase （ATP） separation, is widely applicable to any SWCNT source （tested on samples up to 1.7 nm in diameter） and independent of defect density, purity, diameter, and length. The extracted dispersions demonstrate that the removal of large aggregates, small bundles, and impurities is comparable to that by density gradient ultracentrifugation, but without the need for high-end instrumentation. Raman and fluorescence-excitation spectroscopy, single-nanotube fluorescence imaging, atomic force and transmission electron microscopy, and thermogravimetric analysis all confirm the high purity of the isolated SWCNTs. By predispersing the SWCNTs without sonication （only gentle stirring）, full-length, pristine SWCNTs can be isolated （tested up to 20 μm）. Hence, this simple ATP method will find immediate application in the generation of SWCNT materials for all levels of nanotube research and applications, from fundamental studies to high-performance devices.展开更多
Radiofrequency coil is one of the most important components for a nuclear magnetic resonance(NMR)instrument.In this article,some planar micro coils with an inner diameter of 2 mm and number of turns that varied from 1...Radiofrequency coil is one of the most important components for a nuclear magnetic resonance(NMR)instrument.In this article,some planar micro coils with an inner diameter of 2 mm and number of turns that varied from 1 to 11 were investigated based on the printed circuit board(PCB)technology.The electrical characterization of micro coils show that self-resonant frequencies are larger than 200 MHz.Then,an NMR measurement platform with a static magnetic field of 0.66 T was constructed and the signal to noise ratio(SNR)values of the NMR were analyzed.It was found that the SNR is optimal when the turn number of the micro coils is six and the excitation time of a 90°pulse is 0.8?s.Finally,we used the micro coil with six turns to study the transverse relaxation rate of copper sulfate pentahydrate aqueous solution with different concentrations.It was found that the transverse relaxation rate is proportional to the solution concentration.Results from the micro coil were verified by measurements using a Bruker Minispec MQ60.展开更多
文摘An integrated micro positioning xy-stage with a 2mm × 2mm-area shuttle is fabricated for application in nano- meter-scale operation and nanometric positioning precision. It is mainly composed of a silicon-based xy-stage,electrostatics comb actuator,and a displacement sensor based on a vertical sidewall surface piezoresistor. They are all in a monolithic chip and developed using double-sided bulk-micromachining technology. The high-aspect-ratio comb-driven xy-stage is achieved by deep reactive ion etching （DRIE） in both sides of the wafer. The detecting piezoresistor is located at the vertical sidewall surface of the detecting beam to improve the sensitivity and displacement resolution of the piezoresistive sensors using the DRIE technology combined with the ion implantation technology. The experimental results verify the integrated micro positioning xy-stage design including the micro xy-stage, electrostatics comb actuator,and the vertical sidewall surface piezoresistor technique. The sensitivity of the fabricated piezoresistive sensors is better than 1.17mV/μm without amplification and the linearity is better than 0. 814%. Under 30V driving voltage, a ± 10vm single-axis displacement is measured without crosstalk and the resonant frequency is measured at 983Hz in air.
文摘Isolation and purification of single-walled carbon nanotubes （SWCNTs） are prerequisites for their implementation in various applications. In this work, we present a fast （-5 min）, low-cost, and easily scalable bench-top approach to the extraction of high-quality isolated SWCNTs from bundles and impurities in an aqueous dispersion. The extraction procedure, based on aqueous two-phase （ATP） separation, is widely applicable to any SWCNT source （tested on samples up to 1.7 nm in diameter） and independent of defect density, purity, diameter, and length. The extracted dispersions demonstrate that the removal of large aggregates, small bundles, and impurities is comparable to that by density gradient ultracentrifugation, but without the need for high-end instrumentation. Raman and fluorescence-excitation spectroscopy, single-nanotube fluorescence imaging, atomic force and transmission electron microscopy, and thermogravimetric analysis all confirm the high purity of the isolated SWCNTs. By predispersing the SWCNTs without sonication （only gentle stirring）, full-length, pristine SWCNTs can be isolated （tested up to 20 μm）. Hence, this simple ATP method will find immediate application in the generation of SWCNT materials for all levels of nanotube research and applications, from fundamental studies to high-performance devices.
基金supported by the National Natural Science Foundation of China(Grant No.51175083)the Jiangsu Province University Industry Cooperation Innovation Foundation-Prospective Study of China(Grant No.BY 2011135)
文摘Radiofrequency coil is one of the most important components for a nuclear magnetic resonance(NMR)instrument.In this article,some planar micro coils with an inner diameter of 2 mm and number of turns that varied from 1 to 11 were investigated based on the printed circuit board(PCB)technology.The electrical characterization of micro coils show that self-resonant frequencies are larger than 200 MHz.Then,an NMR measurement platform with a static magnetic field of 0.66 T was constructed and the signal to noise ratio(SNR)values of the NMR were analyzed.It was found that the SNR is optimal when the turn number of the micro coils is six and the excitation time of a 90°pulse is 0.8?s.Finally,we used the micro coil with six turns to study the transverse relaxation rate of copper sulfate pentahydrate aqueous solution with different concentrations.It was found that the transverse relaxation rate is proportional to the solution concentration.Results from the micro coil were verified by measurements using a Bruker Minispec MQ60.
