In order to simplify the fabrication process,distribute the temperature uniformly and reduce the power consumption of the micro-hotplate（MHP） gas sensor,a planar-type gas sensor based on SnO2 thin film with suspende...In order to simplify the fabrication process,distribute the temperature uniformly and reduce the power consumption of the micro-hotplate（MHP） gas sensor,a planar-type gas sensor based on SnO2 thin film with suspended structure is designed through a MEMS process.Steady-state thermal analysis of the gas sensor and the closed membrane type sensor where the membrane overlaps the Si substrate is carried out with the finite element model,and it is shown that the suspended planar-type gas sensor has a more homogeneous temperature distribution and a lower power consumption.When the maximum temperature on the sensor reaches 383℃,the power consumption is only 7 mW,and the temperature gradient across the thin film is less than 14℃.To overcome the fragility of the suspended beams,a novel fabrication process in which the deposition of the gas sensing film occurs prior to the formation of suspended beams is proposed.The back side of the Si substrate is etched through deep reactive ion etching（DRIE） to avoid chemical pollution of the front side.The fabrication steps in which only four masks are used for the photolithography are described in detail.The Fe doped SnO2 thin film synthesized by sol-gel spin-coating is used as the gas sensing element.The device is tested on hydrogen and exhibits satisfactory sensing performance.The sensitivity increases with the rise of the concentration from 50×10-6 to 2000×10-6,and reaches about 30 at 2000×10-6.展开更多
A new silicon beam resonator design for a novel gas sensor based on simultaneous conductivity and mass change measurement is investigated. High selectivity and sensitivity in gas detection can be obtained by measuring...A new silicon beam resonator design for a novel gas sensor based on simultaneous conductivity and mass change measurement is investigated. High selectivity and sensitivity in gas detection can be obtained by measuring the charge-to-mass ratio of gas molecules. Structures of silicon beam resonators are designed, simulated, and optimized. This gas sensor is fabricated using sacrificial layer microelectronmechanical system technology, and the resonant frequency of the microbeam is measured.展开更多
In order to solve the in-situ measurement problem of workpiece with complex structures,a cantilever coordinate measuring machine(CCMM)is proposed to adapt to the finite space constraints of the 5-axis computer numeric...In order to solve the in-situ measurement problem of workpiece with complex structures,a cantilever coordinate measuring machine(CCMM)is proposed to adapt to the finite space constraints of the 5-axis computer numerical control(CNC)processing site.Structure design of dense ball bearing shafting is analyzed and optimized.Factors affecting measurement accuracy of CCMM are analyzed,and measurement accuracy is validated by experiments.Results show that the structure of CCMM is able to satisfy requirements of technical specification,and the in-situ measurement of blisk manufacturing is realized.The CCMM developed is of important significance for machining quantity improvement of blisk and development of large aircraft production.展开更多
基金The National Natural Science Foundation of China (No.58175122)the Natural Science Foundation of Jiangsu Province (No.BK2007185)+1 种基金the Natural Science Foundation of Higher Education Institutions of Jiangsu Province(No.07KJB460044)the Scientific Research Innovation Project for College Graduates in Jiangsu Province (No.CXZZ11_0340)
文摘In order to simplify the fabrication process,distribute the temperature uniformly and reduce the power consumption of the micro-hotplate（MHP） gas sensor,a planar-type gas sensor based on SnO2 thin film with suspended structure is designed through a MEMS process.Steady-state thermal analysis of the gas sensor and the closed membrane type sensor where the membrane overlaps the Si substrate is carried out with the finite element model,and it is shown that the suspended planar-type gas sensor has a more homogeneous temperature distribution and a lower power consumption.When the maximum temperature on the sensor reaches 383℃,the power consumption is only 7 mW,and the temperature gradient across the thin film is less than 14℃.To overcome the fragility of the suspended beams,a novel fabrication process in which the deposition of the gas sensing film occurs prior to the formation of suspended beams is proposed.The back side of the Si substrate is etched through deep reactive ion etching（DRIE） to avoid chemical pollution of the front side.The fabrication steps in which only four masks are used for the photolithography are described in detail.The Fe doped SnO2 thin film synthesized by sol-gel spin-coating is used as the gas sensing element.The device is tested on hydrogen and exhibits satisfactory sensing performance.The sensitivity increases with the rise of the concentration from 50×10-6 to 2000×10-6,and reaches about 30 at 2000×10-6.
文摘A new silicon beam resonator design for a novel gas sensor based on simultaneous conductivity and mass change measurement is investigated. High selectivity and sensitivity in gas detection can be obtained by measuring the charge-to-mass ratio of gas molecules. Structures of silicon beam resonators are designed, simulated, and optimized. This gas sensor is fabricated using sacrificial layer microelectronmechanical system technology, and the resonant frequency of the microbeam is measured.
基金National Natural Science Foundation of China(No.51375338)
文摘In order to solve the in-situ measurement problem of workpiece with complex structures,a cantilever coordinate measuring machine(CCMM)is proposed to adapt to the finite space constraints of the 5-axis computer numerical control(CNC)processing site.Structure design of dense ball bearing shafting is analyzed and optimized.Factors affecting measurement accuracy of CCMM are analyzed,and measurement accuracy is validated by experiments.Results show that the structure of CCMM is able to satisfy requirements of technical specification,and the in-situ measurement of blisk manufacturing is realized.The CCMM developed is of important significance for machining quantity improvement of blisk and development of large aircraft production.
