We present a micro-Pirani vacuum gauge using the low-resistivity monocrystal silicon as the heaters and heat sinks fabricated by the post complementary metal oxide semiconductor （CMOS） microelectromechanical system ...We present a micro-Pirani vacuum gauge using the low-resistivity monocrystal silicon as the heaters and heat sinks fabricated by the post complementary metal oxide semiconductor （CMOS） microelectromechanical system （MEMS） process. The metal interconnection of the device is fabricated by a 0.5 μm standard CMOS process on 8-inch silicon wafer. Then, a SiO2-Si low-temperature fusion bonding is developed to bond the CMOS wafer and the MEMS wafer, with the electrical connection realized by the tungsten through silicon via process. Wafer- level A1Ge euteetic bonding is adopted to package the Pirani gauge in a non-hermetic cavity to protect the gauge from being damaged or contaminated in the dicing and assembling process, and to make it suitable for actual applications. To increase the accuracy of the test and restrain negative influence of temperature drift, the Wheatstone bridge structure is introduced. The test results show that before capping, the gauge has an average sensitivity of 1.04 × 104 K.W-1Torr-1 in dynamic range of 0.01 20 Torr. After capping, the sensitivity of the gauge does not decrease but increases to 1.12 × 104 K.W-1 Torr-1.展开更多
In this article,a CMOS-compatible Pirani vacuum gauge was proposed featuring enhanced sensitivity,lower detection limit,and high-temperature stability,achieved through the implementation of a surface micromachining me...In this article,a CMOS-compatible Pirani vacuum gauge was proposed featuring enhanced sensitivity,lower detection limit,and high-temperature stability,achieved through the implementation of a surface micromachining method coupled with a temperature compensation strategy.To improve performance,a T-type device with a 1μm gap was fabricated resulting in an average sensitivity of 1.10 V/lgPa,which was 2.89 times larger than that(0.38 V/lgPa)of a L-type device with a 100μm gap.Additionally,FEA simulations were conducted,analyzing the influence of heater temperature on sensitivity and the attenuation of sensitivity across varying ambient temperatures.A semi-empirical theoretical mode was derived for performance prediction,demonstrating strong alignment with experimental results,underscoring its effectiveness in compensating for sensitivity attenuation.Building on the foundation,the device’s performance under different ambient temperatures was characterized and effectively compensated in two distinct operational modes:constant temperature mode and constant temperature difference mode(the whole range temperature compensation error can be controlled within 2.5%).Finally,the short-time stability(variation level is approximately 1 mV),noise floor(Vrms=384μV)and detection limit(0.07 Pa@1 Hz)of the device were characterized,confirming its suitability for practical implementation.展开更多
Exposure of absolute pressure sensors, resonant microtube density, binary concentration sensors and chip-scale vacuum packaged pirani gauges to room temperature helium resulted in a gradual drift in sensor output. No ...Exposure of absolute pressure sensors, resonant microtube density, binary concentration sensors and chip-scale vacuum packaged pirani gauges to room temperature helium resulted in a gradual drift in sensor output. No effect was found for differential pressure sensors and pirani gauges vacuum packaged with ceramic or metal packages. The observed results apply to other vacuum packaged MEMS devices such as gyroscopes, voltage controlled oscillators, infrared and Coriolis mass flow sensors. Potential causes for this loss of hermeticity are discussed as well as application limitations for MEMS sensors.展开更多
Clubfoot malformation is the most common serious congenital anomaly affecting the foot in children. Its treatment by the Ponseti method is simple, profitable and widely used in the world. Objective: The objective of t...Clubfoot malformation is the most common serious congenital anomaly affecting the foot in children. Its treatment by the Ponseti method is simple, profitable and widely used in the world. Objective: The objective of this study was to identify the factors of the failure of its treatment by the Ponseti method. Material and Method: We carried out a retrospective and descriptive study of cases of congenital equinus clubfoot varus at the Reference Health Care Center of Commune III of Bamako over 26 months from September 2020 to November 2022. Data were treated with the utmost anonymity. Result: This study was performed on 44 children seen for clubfoot: male (68%) and female (32%), with a sex ratio of 2.1. We obtained 13 cases of recidivism including 7 boys and 6 girls. We found 21 cases of unilateral and 23 bilateral;among which 9 recurrences were found against 4 in the unilateral forms. 85% of recurrences did not have good adherence to the splint and 62% did not come regularly for follow-up consultation. We obtained 33 children with idiopathic clubfeet (75%) with a recurrence of 24%, and 7 children with secondary clubfeet with 71 % recurrence. There was no recurrence in the postural type. Among the recurrences, 38.5% started treatment between 1 and 6 months, 23.1% from 0 to 1 month and 15.4% at 2 years and more. 85% of recurrences had a Pirani score between 4.5 to 6 at the start of treatment and 15% at a score of 2.5 to 4. Conclusion: The factors of the failure of the Ponseti method are mainly non-compliance with treatment, secondary clubfeet, and a high Pirani score at the start of treatment.展开更多
基金Supported by the National High Technology Research and Development Program of China under Grant No 2015AA042602
文摘We present a micro-Pirani vacuum gauge using the low-resistivity monocrystal silicon as the heaters and heat sinks fabricated by the post complementary metal oxide semiconductor （CMOS） microelectromechanical system （MEMS） process. The metal interconnection of the device is fabricated by a 0.5 μm standard CMOS process on 8-inch silicon wafer. Then, a SiO2-Si low-temperature fusion bonding is developed to bond the CMOS wafer and the MEMS wafer, with the electrical connection realized by the tungsten through silicon via process. Wafer- level A1Ge euteetic bonding is adopted to package the Pirani gauge in a non-hermetic cavity to protect the gauge from being damaged or contaminated in the dicing and assembling process, and to make it suitable for actual applications. To increase the accuracy of the test and restrain negative influence of temperature drift, the Wheatstone bridge structure is introduced. The test results show that before capping, the gauge has an average sensitivity of 1.04 × 104 K.W-1Torr-1 in dynamic range of 0.01 20 Torr. After capping, the sensitivity of the gauge does not decrease but increases to 1.12 × 104 K.W-1 Torr-1.
基金funded by the National Natural Science Foundation of China(62304023)partially funded by the National Key R&D Program of China(2023YFB3507300)+1 种基金Natural Science Foundation of Chongqing(2022NSCQ-MSX5423)Beijing Institute of Technology Research Fund Program for Young Scholars(XSQD-202206004).
文摘In this article,a CMOS-compatible Pirani vacuum gauge was proposed featuring enhanced sensitivity,lower detection limit,and high-temperature stability,achieved through the implementation of a surface micromachining method coupled with a temperature compensation strategy.To improve performance,a T-type device with a 1μm gap was fabricated resulting in an average sensitivity of 1.10 V/lgPa,which was 2.89 times larger than that(0.38 V/lgPa)of a L-type device with a 100μm gap.Additionally,FEA simulations were conducted,analyzing the influence of heater temperature on sensitivity and the attenuation of sensitivity across varying ambient temperatures.A semi-empirical theoretical mode was derived for performance prediction,demonstrating strong alignment with experimental results,underscoring its effectiveness in compensating for sensitivity attenuation.Building on the foundation,the device’s performance under different ambient temperatures was characterized and effectively compensated in two distinct operational modes:constant temperature mode and constant temperature difference mode(the whole range temperature compensation error can be controlled within 2.5%).Finally,the short-time stability(variation level is approximately 1 mV),noise floor(Vrms=384μV)and detection limit(0.07 Pa@1 Hz)of the device were characterized,confirming its suitability for practical implementation.
文摘Exposure of absolute pressure sensors, resonant microtube density, binary concentration sensors and chip-scale vacuum packaged pirani gauges to room temperature helium resulted in a gradual drift in sensor output. No effect was found for differential pressure sensors and pirani gauges vacuum packaged with ceramic or metal packages. The observed results apply to other vacuum packaged MEMS devices such as gyroscopes, voltage controlled oscillators, infrared and Coriolis mass flow sensors. Potential causes for this loss of hermeticity are discussed as well as application limitations for MEMS sensors.
文摘Clubfoot malformation is the most common serious congenital anomaly affecting the foot in children. Its treatment by the Ponseti method is simple, profitable and widely used in the world. Objective: The objective of this study was to identify the factors of the failure of its treatment by the Ponseti method. Material and Method: We carried out a retrospective and descriptive study of cases of congenital equinus clubfoot varus at the Reference Health Care Center of Commune III of Bamako over 26 months from September 2020 to November 2022. Data were treated with the utmost anonymity. Result: This study was performed on 44 children seen for clubfoot: male (68%) and female (32%), with a sex ratio of 2.1. We obtained 13 cases of recidivism including 7 boys and 6 girls. We found 21 cases of unilateral and 23 bilateral;among which 9 recurrences were found against 4 in the unilateral forms. 85% of recurrences did not have good adherence to the splint and 62% did not come regularly for follow-up consultation. We obtained 33 children with idiopathic clubfeet (75%) with a recurrence of 24%, and 7 children with secondary clubfeet with 71 % recurrence. There was no recurrence in the postural type. Among the recurrences, 38.5% started treatment between 1 and 6 months, 23.1% from 0 to 1 month and 15.4% at 2 years and more. 85% of recurrences had a Pirani score between 4.5 to 6 at the start of treatment and 15% at a score of 2.5 to 4. Conclusion: The factors of the failure of the Ponseti method are mainly non-compliance with treatment, secondary clubfeet, and a high Pirani score at the start of treatment.
