Thermal-actuation and piezoresistive-detection effects have been employed to pump the effective quality factor of MEMS resonators,targeting simple self-oscillation and better sensing performance in the air.However,the...Thermal-actuation and piezoresistive-detection effects have been employed to pump the effective quality factor of MEMS resonators,targeting simple self-oscillation and better sensing performance in the air.However,the ratio of the pumped effective quality factor to the inherent mechanical quality factor,crucial for characterizing the amplification,is hard to obtain.The main difficulty stems from hidden Lorentz peaks caused by feedthrough effects and the pump effect once the current is applied.In this paper,we demonstrated the presence of high-order harmonic components in the output of thermal-piezoresistive resonators when the oscillation amplitude is sufficiently large.By utilizing second-order harmonics,we achieved the improvement in signal-to-bias ratio of,20.85 dB compared to that without feedthrough cancellation and 9.67 dB compared to that using a de-embedded method when the bias current is 6.20 mA.Furthermore,the inherent mechanical quality factor is extracted at a low current of 1.8 mA with a value of 5800 using the second-order harmonics,and a nearly two orders of magnitude enhancement in Q factor can be obtained before entering the self-oscillation regime.An amplitude bias instability as good as 55 ppm and a frequency bias instability as good as 10 ppb are realized in the nonlinear operation regime with a pumped effective quality factor of 576k.The paper contributes to the fundamental understanding of the Q pump effect together with harmonic analysis of the thermal-piezoresistive resonators and also pushes forward the development of low-power consumption self-oscillation resonant sensors.展开更多
Objective To explore the effects of cognitive intervention on the quality of life in patients with functional dyspepsia(FD).Methods From May 2013 to February2015,a total of 412 patients with FD were enrolled,cognition...Objective To explore the effects of cognitive intervention on the quality of life in patients with functional dyspepsia(FD).Methods From May 2013 to February2015,a total of 412 patients with FD were enrolled,cognition of the disease and the quality of life were assessed by disease cognitive simple questionnaire(B-IPQ)and Nepean dyspepsia index(NDI).The patients also re-展开更多
This study demonstrates amplification of electrical signals using a very simple nanomechanical device.It is shown that vibration amplitude amplification using a combination of mechanical resonance and thermal-piezores...This study demonstrates amplification of electrical signals using a very simple nanomechanical device.It is shown that vibration amplitude amplification using a combination of mechanical resonance and thermal-piezoresistive energy pumping,which was previously demonstrated to drive self-sustained mechanical oscillation,can turn the relatively weak piezoresistivity of silicon into a viable electronic amplification mechanism with power gains of 420 dB.Various functionalities ranging from frequency selection and timing to sensing and actuation have been successfully demonstrated for microscale and nanoscale electromechanical systems.Although such capabilities complement solid-state electronics,enabling state-of-the-art compact and high-performance electronics,the amplification of electronic signals is an area where micro-/nanomechanics has not experienced much progress.In contrast to semiconductor devices,the performance of the proposed nanoelectromechanical amplifier improves significantly as the dimensions are reduced to the nanoscale presenting a potential pathway toward deep-nanoscale electronics.The nanoelectromechanical amplifier can also address the need for ultranarrow-band filtering along with the amplification of lowpower signals in wireless communications and certain sensing applications,which is another need that is not efficiently addressable using semiconductor technology.展开更多
基金supported by the National Key R&D Program of China No.2023YFB3208800the National Science Foundation of China No.52475606 and 52435012+1 种基金the Fundamental Research Funds for the Central Universities,Innovation Capability Support Program of Shaanxi(Program No.2024RS-CXTD-17)Natural Science Basic Research Plan in Shaanxi Province of China(Program No.2023JC-XJ-07).
文摘Thermal-actuation and piezoresistive-detection effects have been employed to pump the effective quality factor of MEMS resonators,targeting simple self-oscillation and better sensing performance in the air.However,the ratio of the pumped effective quality factor to the inherent mechanical quality factor,crucial for characterizing the amplification,is hard to obtain.The main difficulty stems from hidden Lorentz peaks caused by feedthrough effects and the pump effect once the current is applied.In this paper,we demonstrated the presence of high-order harmonic components in the output of thermal-piezoresistive resonators when the oscillation amplitude is sufficiently large.By utilizing second-order harmonics,we achieved the improvement in signal-to-bias ratio of,20.85 dB compared to that without feedthrough cancellation and 9.67 dB compared to that using a de-embedded method when the bias current is 6.20 mA.Furthermore,the inherent mechanical quality factor is extracted at a low current of 1.8 mA with a value of 5800 using the second-order harmonics,and a nearly two orders of magnitude enhancement in Q factor can be obtained before entering the self-oscillation regime.An amplitude bias instability as good as 55 ppm and a frequency bias instability as good as 10 ppb are realized in the nonlinear operation regime with a pumped effective quality factor of 576k.The paper contributes to the fundamental understanding of the Q pump effect together with harmonic analysis of the thermal-piezoresistive resonators and also pushes forward the development of low-power consumption self-oscillation resonant sensors.
文摘Objective To explore the effects of cognitive intervention on the quality of life in patients with functional dyspepsia(FD).Methods From May 2013 to February2015,a total of 412 patients with FD were enrolled,cognition of the disease and the quality of life were assessed by disease cognitive simple questionnaire(B-IPQ)and Nepean dyspepsia index(NDI).The patients also re-
基金This work was supported by National Science Foundation CAREER grant No.1056068.
文摘This study demonstrates amplification of electrical signals using a very simple nanomechanical device.It is shown that vibration amplitude amplification using a combination of mechanical resonance and thermal-piezoresistive energy pumping,which was previously demonstrated to drive self-sustained mechanical oscillation,can turn the relatively weak piezoresistivity of silicon into a viable electronic amplification mechanism with power gains of 420 dB.Various functionalities ranging from frequency selection and timing to sensing and actuation have been successfully demonstrated for microscale and nanoscale electromechanical systems.Although such capabilities complement solid-state electronics,enabling state-of-the-art compact and high-performance electronics,the amplification of electronic signals is an area where micro-/nanomechanics has not experienced much progress.In contrast to semiconductor devices,the performance of the proposed nanoelectromechanical amplifier improves significantly as the dimensions are reduced to the nanoscale presenting a potential pathway toward deep-nanoscale electronics.The nanoelectromechanical amplifier can also address the need for ultranarrow-band filtering along with the amplification of lowpower signals in wireless communications and certain sensing applications,which is another need that is not efficiently addressable using semiconductor technology.
