Experimental Study on Aerodynamics of Microelectromechanical Systems Based Single-Crystal-Silicon Microscale Supersonic Nozzle

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Moriaki Namura ◽  
Toshiyuki Toriyama
Keyword(s):  
New York ◽  
Single Crystal ◽  
Microelectromechanical Systems ◽  
Supersonic Nozzle ◽  
Single Crystal Silicon ◽  
Internal Flow ◽  
Nozzle Flow ◽  
Crystal Silicon ◽  
Rarefied Flow ◽  
Silicon Bulk

In this paper, the design, microfabrication, and direct measurement of the static pressure distribution for the aerodynamics of a single-crystal-silicon microscale supersonic nozzle are described. The microscale supersonic nozzle has a convergent–divergent section and a throat area of 100μm × 300μm. The microscale supersonic nozzle was fabricated by silicon bulk micromachining technology. The degree of the rarefaction of nozzle flow was determined by the Knudsen number (Kn). The operation envelope that determines whether the continuum or rarefied flow assumption is appropriate can be expressed as a function of Kn and related parameters. The effect of nonadiabatic operation on microscale nozzle flow was investigated on the basis of wall heat transfer. These physical correlations were taken into account for the classical Shapiro's equations to analyze the microscale nozzle flow aerodynamics (Shapiro, 1953, The Dynamics and Thermodynamics of Compressible Fluid Flow, Ronald, New York, Chap. 7,8; Greitzer et al., 2006, Internal Flow, Cambridge University, Cambridge, UK, Chap. 2,10). Furthermore, the solutions of Shapiro's equations were compared with the experimental results by the authors and other research institutions in order to demonstrate the validity of the proposed aerodynamics design concept for microscale continuum flow.

Thermal Conductivity of Single-Crystal Silicon Microbridges Measured by Electrical Resistance Thermometry and Time-Domain Thermoreflectance

2012 ◽  
Author(s):  
Timothy S. English ◽  
Leslie M. Phinney ◽  
Patrick E. Hopkins ◽  
Justin R. Serrano
Keyword(s):  
Thermal Conductivity ◽  
Single Crystal ◽  
Time Domain ◽  
Electrical Resistance ◽  
Microelectromechanical Systems ◽  
Single Crystal Silicon ◽  
Operating Conditions ◽  
Equation Modeling ◽  
Crystal Silicon ◽  
Resistance Thermometry

Accurate thermal conductivity values are essential to the modeling, design, and thermal management of microelectromechanical systems (MEMS) and devices. However, the experimental technique best suited to measure thermal conductivity, as well as thermal conductivity itself, varies with the device materials, fabrication conditions, geometry, and operating conditions. In this study, the thermal conductivity of boron doped single-crystal silicon-on-insulator (SOI) microbridges is measured over the temperature range from 77 to 350 K. The microbridges are 4.6 mm long, 125 μm tall, and two widths, 50 or 85 μm. Measurements on the 85 μm wide microbridges are made using both steady-state electrical resistance thermometry and optical time-domain thermoreflectance. A thermal conductivity of ∼ 77 W/mK is measured for both microbridge widths at room temperature, where both experimental techniques agree. However, a discrepancy at lower temperatures is attributed to differences in the interaction volumes and in turn, material properties, probed by each technique. This finding is qualitatively explained through Boltzmann transport equation modeling under the relaxation time approximation.

A high Q micromachined single crystal silicon bulk mode resonator with pre-etched cavity

2011 ◽  
Vol 18 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Guoqiang Wu ◽  
Dehui Xu ◽  
Bin Xiong ◽  
Yuelin Wang
Keyword(s):  
Single Crystal ◽  
Single Crystal Silicon ◽  
Crystal Silicon ◽  
High Q ◽  
Bulk Mode ◽  
Silicon Bulk ◽  
Mode Resonator

Micromechanical and tribological characterization of doped single-crystal silicon and polysilicon films for microelectromechanical systems devices

1997 ◽  
Vol 12 (1) ◽  
pp. 54-63 ◽  
Author(s):  
Bharat Bhushan ◽  
Xiaodong Li
Keyword(s):  
Single Crystal ◽  
Microelectromechanical Systems ◽  
Single Crystal Silicon ◽  
Crystal Silicon ◽  
Polysilicon Film ◽  
Type Silicon ◽  
Boron Doped ◽  
Polysilicon Films ◽  
Tribological Characterization

Microelectromechanical systems (MEMS) devices are made of doped single-crystal silicon, LPCVD polysilicon films, and other ceramic films. Very little is understood about tribology and mechanical characterization of these materials on micro- to nanoscales. Micromechanical and tribological characterization of p-type (lightly boron-doped) single-crystal silicon (referred to as “undoped”), p+-type (boron doped) single-crystal silicon, polysilicon bulk, and n+-type (phosphorous doped) LPCVD polysilicon films have been carried out. Hardness, elastic modulus, and scratch resistance of these materials were measured by nanoindentation and microscratching using a nanoindenter. Friction and wear properties were measured using an accelerated ball-on-flat tribometer. It is found that the undoped silicon and polysilicon bulk as well as n+-type polysilicon film exhibit higher hardness and elastic modulus than the p+-type silicon. The polysilicon bulk and n+-type polysilicon film exhibit the lowest friction and highest resistance to scratch and wear followed by the undoped silicon and with the poorest behavior of the p+-type silicon. During scratching, the p+-type silicon deforms like a ductile metal.

Aero-Thermodynamic Consideration of Single-Crystal-Silicon Premixed-Fuel Microscale Can Combustor

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Moriaki Namura ◽  
Toshiyuki Toriyama
Keyword(s):  
Single Crystal ◽  
Physical Interpretation ◽  
Burning Velocity ◽  
Single Crystal Silicon ◽  
Velocity Model ◽  
Flame Stabilization ◽  
Crystal Silicon ◽  
Thermodynamic Consideration ◽  
Stable Combustion ◽  
Silicon Bulk

This paper describes the aero-thermodynamic design, microfabrication and combustion test results for a single-crystal-silicon premixed-fuel microscale can combustor. The combustion chamber volume is 277 mm3, and the microscale can combustor was fabricated by silicon bulk micromachining technology. Hydrogen fuel-air premixing was performed in the combustion test. The operation space in which stable combustion occurred was experimentally determined from the combustion temperature and efficiency for various mass flow rates and equivalence ratios. The expression for the combustion efficiency under conditions where the overall rate of heat release is limited by the chemical kinetics was consistent with the burning velocity model. The flame stabilization, the range of equivalence ratios and the maximum air velocity that the combustor can tolerate before flame extinction occurs were in agreement with the well - stirred reactor (WSR) and combustion loading parameter (CLP) models. A proposed aero-thermodynamic design approach based on these three models provides a physical interpretation of the experimental results in the operation space of stable combustion. Furthermore, this approach provides a unified physical interpretation of the stable combustion operation spaces of microscale combustors with various dimensions and configurations. Therefore, it is demonstrated that the proposed aero-thermodynamic approach has an important role in predicting the preliminary aerodynamic design performances of new microscale combustors.

scholarly journals Novel Gas Sensor Arrays Based on High-Q SAM-Modified Piezotransduced Single-Crystal Silicon Bulk Acoustic Resonators

Sensors ◽  
2017 ◽  
Vol 17 (7) ◽  
pp. 1507 ◽  
Author(s):  
Yuan Zhao ◽  
Qingrui Yang ◽  
Ye Chang ◽  
Wei Pang ◽  
Hao Zhang ◽  
...  
Keyword(s):  
Single Crystal ◽  
Gas Sensor ◽  
Sensor Arrays ◽  
Single Crystal Silicon ◽  
Crystal Silicon ◽  
Acoustic Resonators ◽  
High Q ◽  
Silicon Bulk ◽  
Gas Sensor Arrays

scholarly journals A Single-Crystal-Silicon Bulk-Acoustic-Mode Microresonator Oscillator

2008 ◽  
Vol 29 (7) ◽  
pp. 701-703 ◽  
Author(s):  
Joshua E.-Y. Lee ◽  
Behraad Bahreyni ◽  
Yong Zhu ◽  
Ashwin A. Seshia
Keyword(s):  
Single Crystal ◽  
Single Crystal Silicon ◽  
Acoustic Mode ◽  
Crystal Silicon ◽  
Silicon Bulk

Mean Free Path Effects on the Experimentally Measured Thermal Conductivity of Single-Crystal Silicon Microbridges

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Timothy S. English ◽  
Leslie M. Phinney ◽  
Patrick E. Hopkins ◽  
Justin R. Serrano
Keyword(s):  
Thermal Conductivity ◽  
Single Crystal ◽  
Microelectromechanical Systems ◽  
Single Crystal Silicon ◽  
Operating Conditions ◽  
Silicon On Insulator ◽  
Beam Diameter ◽  
Boltzmann Transport ◽  
Crystal Silicon ◽  
Thermal Conductivities

Accurate thermal conductivity values are essential for the successful modeling, design, and thermal management of microelectromechanical systems (MEMS) and devices. However, the experimental technique best suited to measure the thermal conductivity of these systems, as well as the thermal conductivity itself, varies with the device materials, fabrication processes, geometry, and operating conditions. In this study, the thermal conductivities of boron doped single-crystal silicon microbridges fabricated using silicon-on-insulator (SOI) wafers are measured over the temperature range from 80 to 350 K. The microbridges are 4.6 mm long, 125 μm tall, and either 50 or 85 μm wide. Measurements on the 85 μm wide microbridges are made using both steady-state electrical resistance thermometry (SSERT) and optical time-domain thermoreflectance (TDTR). A thermal conductivity of 77 Wm−1 K−1 is measured for both microbridge widths at room temperature, where the results of both experimental techniques agree. However, increasing discrepancies between the thermal conductivities measured by each technique are found with decreasing temperatures below 300 K. The reduction in thermal conductivity measured by TDTR is primarily attributed to a ballistic thermal resistance contributed by phonons with mean free paths larger than the TDTR pump beam diameter. Boltzmann transport equation (BTE) modeling under the relaxation time approximation (RTA) is used to investigate the discrepancies and emphasizes the role of different interaction volumes in explaining the underprediction of TDTR measurements.

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