Characterization of a Knudsen force based vacuum sensor for N2H2O gas mixtures

Pikus, Aaron; Sebastião, Israel B.; Strongrich, Andrew; Alexeenko, Alina

doi:10.1016/j.vacuum.2018.12.003

Cited by 17 publications

(16 citation statements)

References 15 publications

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“…If the pressure continues to increase, the center of vortex A will move away from the heater arm. The qualitative variation of gas flow pattern for different pressures was observed in the previous research of the original design [ 28 , 29 , 30 , 35 , 36 ].…”

Section: Resultsmentioning

confidence: 53%

“…The reason is that the temperature difference between the shuttle and heater arms was 64 K and the gas pressure was 62 Pa in [ 38 ], but in the current work, the temperature difference and pressure were considered as 37.5K and 387 Pa, respectively. Temperature difference and pressure are two crucial factors significantly influencing the value of Knudsen force [ 2 , 9 , 10 , 11 , 12 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. On the other hand, a larger Knudsen force was obtained in the case where only one shuttle-heater pair was simulated, neglecting the coupling effects ( Figure 2 b).…”

Section: Resultsmentioning

confidence: 99%

“…DSMC is a highly-efficient method to solve the Boltzmann equation [ 40 , 41 ]. Moreover, the DSMC method has been widely used in the research of rarefied gas flow induced by temperature field [ 42 , 43 , 44 ] and low-pressure gas actuators based on Knudsen force [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ].…”

Section: Numerical Approachmentioning

confidence: 99%

“…On the other hand, within an ambient pressure of 25 Pa to 1500 Pa, MIKRA can achieve the detection of gases (N 2 –H 2 O, Kr–Xe, He–Ne–Ar, N 2 –H 2 , CH 4 –SO 2 , CO 2 , N 2 –NH 3 , and Air–H 2 ) [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. Knudsen force is linearly dependent on the concentration of any gas species in a gas mixture [ 36 ]. Li et al [ 37 ] employed RSM to obtain the correlations between Knudsen force and the factors (pressure, temperature difference between the shuttle and heater arms, gap size, and mass fraction of the hydrogen in the gas mixture) in MIKRA devices.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Improved Design on Knudsen Force for Micro Gas Sensor

Wang

Zhang

et al. 2020

Micromachines

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Knudsen force generated by thermally driven gas flow in a microscale structure has been used for gas detection and has shown immeasurable potential in the field of microelectromechanical system (MEMS) gas sensors due to its novel sensing characteristics. In this article, the performances of three kinds of Knudsen force gas sensors with improved isosceles triangular shuttle arm structures were studied. In the first design, the top side and right side lengths were equal; in the second, the top side and bottom side lengths were equal; and for the third, the bottom side and right side lengths were equal. A detailed investigation including gas flow, thermal characteristics, Knudsen force, and coupling effects between the shuttle-heater pairs was conducted using the direct simulation Monte Carlo (DSMC) method and the main mechanisms for gas flow presented were almost the same in this work. However, the second design returned the highest Knudsen force performance. The value increased by 42.9% (P = 387 Pa) compared to the Knudsen force of the original square shuttle arm. The results also demonstrate that the coupling effects become weak toward the right with an increase in the number of shuttle-heater pairs.

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Section: Resultsmentioning

confidence: 53%

Section: Resultsmentioning

confidence: 99%

Section: Numerical Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Impact of Improved Design on Knudsen Force for Micro Gas Sensor

Wang

Zhang

et al. 2020

Micromachines

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show abstract

“…MIKRA presents an interesting problem for analyzing thermostress convection due to temperature gradients as well as concentration inhomogeneties, see Ref. 54 where authors observed species separation in MIKRA which might be, in part, due to be the effect of k T ∇ ln T term. We believe it's too early to make a definite conclusion on the topic.…”

Section: Introductionmentioning

confidence: 99%

Quantification of thermally-driven flows in microsystems using Boltzmann equation in deterministic and stochastic contexts

et al. 2019

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When the flow is sufficiently rarefied, a temperature gradient, for example, between two walls separated by a few mean free paths, induces a gas flow-an observation attributed to the thermo-stress convection effects at microscale. The dynamics of the overall thermo-stress convection process is governed by the Boltzmann equation-an integro-differential equation describing the evolution of the molecular distribution function in six-dimensional phase space-which models dilute gas behavior at the molecular level to accurately describe a wide range of flow phenomena. Approaches for solving the full Boltzmann equation with general inter-molecular interactions rely on two perspectives: one stochastic in nature often delegated to the direct simulation Monte Carlo (DSMC) method; and the others deterministic by virtue. Among the deterministic approaches, the discontinuous Galerkin fast spectral (DGFS) method has been recently introduced for solving the full Boltzmann equation with general collision kernels, including the variable hard/soft sphere models-necessary for simulating flows involving diffusive transport. In this work, the deterministic DGFS method; Bhatnagar-Gross-Krook (BGK), Ellipsoidal statistical BGK, and Shakhov kinetic models; and the widely-used stochastic DSMC method, are utilized to assess the thermo-stress convection process in MIKRA-Micro In-Plane Knudsen Radiometric Actuator-a microscale compact low-power pressure sensor utilizing the Knudsen forces. BGK model under-predicts the heatflux, shear-stress, and flow speed; S-model over-predicts; whereas ESBGK comes close to the DSMC results. On the other hand, both the statistical/DSMC and deterministic/DGFS methods, segregated in perspectives, yet, yield inextricable results, bespeaking the ingenuity of Graeme Bird who laid down the foundation of practical rarefied gas dynamics for microsystems.

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