Wing Buffeting Control at Transonic Flight Velocities with the Use of Ejector-Type Pulse Thermal Actuators

2018 ◽  
Keyword(s):  
Thermal Actuators

scholarly journals Controlled Fabrication of Quality ZnO NWs/CNTs and ZnO NWs/Gr Heterostructures via Direct Two-Step CVD Method

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1836
Author(s):  
Nicholas Schaper ◽  
Dheyaa Alameri ◽  
Yoosuk Kim ◽  
Brian Thomas ◽  
Keith McCormack ◽  
...  
Keyword(s):  
Direct Synthesis ◽  
Chemical Vapor ◽  
Single Walled Carbon Nanotubes ◽  
Materials Synthesis ◽  
Oxide Nanowires ◽  
Cvd Method ◽  
Thermal Actuators ◽  
Potential Applications ◽  
Walled Carbon Nanotubes ◽  
Scalable Production

A novel and advanced approach of growing zinc oxide nanowires (ZnO NWs) directly on single-walled carbon nanotubes (SWCNTs) and graphene (Gr) surfaces has been demonstrated through the successful formation of 1D–1D and 1D–2D heterostructure interfaces. The direct two-step chemical vapor deposition (CVD) method was utilized to ensure high-quality materials’ synthesis and scalable production of different architectures. Iron-based universal compound molecular ink was used as a catalyst in both processes (a) to form a monolayer of horizontally defined networks of SWCNTs interfaced with vertically oriented ZnO NWs and (b) to grow densely packed ZnO NWs directly on a graphene surface. We show here that our universal compound molecular ink is efficient and selective in the direct synthesis of ZnO NWs/CNTs and ZnO NWs/Gr heterostructures. Heterostructures were also selectively patterned through different fabrication techniques and grown in predefined locations, demonstrating an ability to control materials’ placement and morphology. Several characterization tools were employed to interrogate the prepared heterostructures. ZnO NWs were shown to grow uniformly over the network of SWCNTs, and much denser packed vertically oriented ZnO NWs were produced on graphene thin films. Such heterostructures can be used widely in many potential applications, such as photocatalysts, supercapacitors, solar cells, piezoelectric or thermal actuators, as well as chemical or biological sensors.

Analysis of thermo-mechanical coupling damage behavior in long-term performance of microelectromechanical systems actuators

2021 ◽  
pp. 105678952110339
Author(s):  
Jiaxing Cheng ◽  
Zhaoxia Li
Keyword(s):  
Damage Mechanics ◽  
Microelectromechanical Systems ◽  
Mechanical Performance ◽  
Damage Model ◽  
Irreversible Damage ◽  
Damage Behavior ◽  
Thermal Actuators ◽  
Long Term Performance ◽  
Term Performance

Effective numerical analysis is significant for the optimal design and reliability evaluation of MEMS, but the complexity of multi-physical field couplings and irreversible damage accumulation in long-term performance make the analysis difficult. In the present paper, the continuum damage mechanics method is used to develop a creep damage model and conduct long-term performance analysis for MEMS thermal actuators with coupled thermo-mechanical damage behavior. The developed damage model can make a connection between the material deterioration due to microstructure changes and the macroscopic responses (the change of thermo-mechanical performance or structure failure). The numerical simulations of coupled thermo-mechanical behavior in long-term performance are implemented using the finite element method, which is validated through comparison with previous literature. The numerical results demonstrate that the proposed damage model and numerical method can provide effective assessment in the long-term performance of MEMS thermal actuators.

Linear Thermomechanical Microactuators

1999 ◽  
Author(s):  
Rebecca Cragun ◽  
Larry L. Howell
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Cross Sections ◽  
Variable Cross ◽  
Element Analysis ◽  
Thermal Actuators ◽  
Output Force ◽  
Analysis Models ◽  
High Output

Abstract Thermomechanical in-plane microactuators (TIMs) have been designed, modeled, fabricated, and tested. TIMs offer an alternative to arrays of smaller thermal actuators to obtain high output forces. The design is easily modified to obtain the desired output force or deflection for specific applications. The operational principle is based on the symmetrical thermal expansion of variable cross sections of the surface micromachined microdevice. Sixteen configurations of TIMs were fabricated of polysilicon. Finite element analysis models were used to predict the deflection and output force for the actuators. Experimental results were also recorded for all sixteen configurations, including deflections and output forces up to 20 micron and 35 dyne.

Wafer Level Micropackaging of MEMS Devices Using Thin Film Anodic Bonding

2002 ◽  
Vol 729 ◽  
Author(s):  
Lauren E. S. Rohwer ◽  
Andrew D. Oliver ◽  
Melissa V. Collins
Keyword(s):  
Shear Strength ◽  
Test Sample ◽  
Anodic Bonding ◽  
Mems Devices ◽  
Wafer Level ◽  
Thermal Actuators ◽  
Wafer Level Packaging ◽  
Hermetic Seal ◽  
Leak Testing ◽  
Before And After

AbstractA wafer level packaging technique that involves anodic bonding of Pyrex wafers to released surface micromachined wafers is demonstrated. Besides providing a hermetic seal, this technique allows full wafer release, provides protection during die separation, and offers the possibility of integration with optoelectronic devices. Anodic bonding was performed under applied voltages up to 1000 V, and temperatures ranging from 280 to 400°C under vacuum (10-4Torr). The quality of the bonded interfaces was evaluated using shear strength testing and leak testing. The shear strength of Pyrex-to-polysilicon and aluminum bonds was ∼10-15 MPa. The functionality of surface micromachined polysilicon devices was tested before and after anodic bonding. 100% of thermal actuators, 94% of torsional ratcheting actuators, and 70% of microengines functioned after bonding. The 70% yield was calculated from a test sample of 25 devices.

Multistable Thermal Actuators Via Multimaterial 4D Printing

2018 ◽  
Vol 4 (3) ◽  
pp. 1800495 ◽  
Author(s):  
Hoon Yeub Jeong ◽  
Eunseo Lee ◽  
Sangho Ha ◽  
Namhun Kim ◽  
Young Chul Jun
Keyword(s):  
4D Printing ◽  
Thermal Actuators

Packaging of In-Plane Thermal Microactuators for BioMEMS Applications

2005 ◽  
Author(s):  
Hrishikesh V. Panchawagh ◽  
Faheem F. Faheem ◽  
Cari F. Herrmann ◽  
David B. Serrell ◽  
Dudley S. Finch ◽  
...  
Keyword(s):  
Flip Chip ◽  
Atomic Layer ◽  
Thermal Actuator ◽  
Mems Devices ◽  
Thermal Actuators ◽  
Layer Deposition ◽  
Comb Drives ◽  
Small Clearance ◽  
Surrounding Liquid ◽  
Packaging Technique

This paper addresses two issues related to in-plane, electro-thermal actuators for BioMEMS applications. First, in order to protect the actuator from biological debris and particulates, a packaging technique using a flip-chip bonded polysilicon cap is demonstrated. The encapsulated actuator transmits motion outside the package via a piston, which moves through a small clearance. The second issue addressed is the reduction in efficiency of the thermal actuator in liquids. By coating the packaged actuator with a thin conformal hydrophobic layer via an atomic layer deposition (ALD) process, the liquid is prevented from entering the encapsulation. This avoids direct contact between the actuator and the surrounding liquid thereby improving its efficiency. The unpackaged and packaged actuators were tested in both air and de-ionized water. Although the packaging resulted in a reduction in the performance of the thermal actuator in air, the actuation efficiency in water was significantly improved due to the isolation of the hot arms from the liquid. This packaging technique is also applicable to other MEMS devices and in-plane actuators such as electrostatic comb drives for engineering as well as biological applications.

Modal Simulation and Testing of a Micro-Manipulator

2004 ◽  
Vol 127 (3) ◽  
pp. 515-519 ◽  
Author(s):  
Yongjun Lai ◽  
Marek Kujath ◽  
Ted Hubbard
Keyword(s):  
Numerical Simulations ◽  
Degrees Of Freedom ◽  
Compliant Mechanism ◽  
Dynamic Properties ◽  
Experimental Results ◽  
Mass Model ◽  
Thermal Actuators ◽  
Micro Manipulator ◽  
Six Dof

A micro-machined manipulator with three kinematic degrees-of-freedom (DOF): x, y, and φ is presented. The manipulator is driven by three thermal actuators. A six DOF discrete spring-mass model of the compliant mechanism is developed which manifests the dynamic properties of the device. Numerical simulations are compared with experimental results.

Topology Synthesis of Two-Phase Compliant Actuators

1999 ◽  
Author(s):  
Ole Sigmund
Keyword(s):  
Topology Optimization ◽  
Material Design ◽  
Optimization Method ◽  
The Other ◽  
Design Domain ◽  
Active Materials ◽  
Two Phase ◽  
Thermal Actuators ◽  
Compliant Actuators ◽  
Topology Optimization Method

Abstract This paper describes how the topology optimization method can be used as a tool for the synthesis of two-phase compliant actuators. Two materials, one or both being active materials, are distributed in a design domain such that the work performed on an elastic workpiece is maximized. The two-material design is obtained by introducing two variables per element. One variable determines the relative density of material in the element and the other variable determines the material type. Examples demonstrate the design of thermal actuators and gripping mechanisms.

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