Thin Film NiTi Shape Memory Alloy Microactuator With Two-Way Effect

2000 ◽  
Author(s):  
John J. Gill ◽  
Gregory P. Carman
Keyword(s):  
Thin Film ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Frequency Response ◽  
Microelectromechanical Systems ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Niti Shape Memory Alloy ◽  
Maximum Deflection

Abstract Thin film SMA (Shape memory alloy) is a useful material for MEMS (Microelectromechanical Systems) actuator. This is because the thin film has an improved frequency response compared to bulk SMA, high work density, and produces large strain. A novel two-way thin film NiTi (Nickel Titanium) shape memory alloy actuator is presented in this paper. Thin film shape memory alloy is sputter-deposited onto a silicon wafer in an ultra high vacuum system. Transformation temperatures of the NiTi film are determined by measuring the residual stress as a function of temperature. Test results show that the Martensite-Temperature-Finish (Mf) is approximately 60° C, and the Austenite-Temperature-Finish (Af) is 110° C. A free standing NiTi membrane (12 mm × 12 mm and 2.5 μm thick) is fabricated using MEMS technology. We found that a mixture of HF (Hydro Fluoric Acid), HNO3 (Nitric Acid) and DI (Deionized) water with thick photo resist mask works best for the fabrication process. The membrane is hot-shaped into a dome shape. Results indicate that when the temperature of the NiTi film exceeds Af, the NiTi membrane transforms into the trained hot-shape. When the temperature cools down to room temperature, the membrane returns to the initial flat shape. The performance of the SMA micro actuator is characterized with a laser measurement system for deflection vs. input power and frequency response. The maximum deflection of SMA microactuator is 230 μm. The corresponding frequency responses at the maximum deflection are 30 Hz with Copper (Cu) block placed underneath the microactuator and less than 1 Hz when Plexi-glass is placed.

The Fabrication of Thin Film NiTi Shape Memory Alloy Micro Actuator for MEMS Application

1999 ◽  
Author(s):  
John J. Gill ◽  
Ken Ho ◽  
Gregory P. Carman
Keyword(s):  
Thin Film ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Microelectromechanical Systems ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Niti Shape Memory Alloy ◽  
Cylindrical Shape ◽  
Finish Temperature

Abstract Thin film SMA (Shape memory alloy) is a useful method for MEMS (Microelectromechanical Systems) actuator. This is because the thin film has an improved frequency response compared to bulk SMA, high work density, and produces large strain. A novel two-way thin film NiTi (Nickel Titanium) shape memory alloy actuator is presented in this paper. Thin film shape memory alloy is sputter-deposited onto a silicon wafer in an ultra high vacuum system. Transformation temperatures of the deposited NiTi film are measured by residual stress measurement at temperatures from 25 ° C to 120 ° C. Test results show that the Mf (Martensite Finish Temperature) is around 60 ° C and Af (Austenite Finish Temperature) is around 110 ° C. A free standing NiTi membrane (10 mm × 10mm and 3 μm thick) is fabricated using MEMS technology. We found that a mixture of HF (Hydro Fluidic Acid), HNO3 (Nitric Acid) and DI (Deionized) water with thick photo resist mask works best for the fabrication process. The membrane is hot-shaped in different shapes such as dome shape, pyramidal shape, and cylindrical shape. Results indicate that when the temperature of the NiTi film exceeds Af, the NiTi membrane transforms into the trained hot-shape. When the temperature cools down to room temperature, the membrane returns to the initial flat shape.

Material and Process Development of Thin Film Shape Memory Alloy for MEMS Actuator

2015 ◽  
Author(s):  
Cory R. Knick ◽  
Christopher J. Morris
Keyword(s):  
Thin Film ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Phase Change ◽  
Shape Memory ◽  
Microelectromechanical Systems ◽  
Austenite Phase ◽  
Niti Shape Memory Alloy ◽  
Scanning Calorimetry ◽  
Release Process

In this work we discuss the design and fabrication of a cantilever that may be actuated by utilizing the martensite to austenite phase transformation of a sputtered thin film of equiatomic NiTi shape memory alloy (SMA). The cantilever devices were fabricated on a silicon wafer using standard micro fabrication techniques, and may therefore be applicable to microelectromechanical systems (MEMS) switch or actuator applications. This paper details the development of a co-sputtering process to yield a SMA film with controllable composition of Ni50Ti50 and transformation temperature around 60° C. Shape memory effects were characterized using Differential Scanning Calorimetry (DSC), for which we demonstrated martensite-austenite phase change at 57° C for 1–3 um films, annealed at 600° C. We used wafer stress versus temperature measurements as additional confirmation for the repeatable measurement of reversible phase transformation peaking at 73° C upon heating. Up to 62 MPa was available for actuation during the thermally induced phase change. After exploring multiple approaches to a frontside wafer release process, we were successful in patterning and fabricating 10 um wide freestanding Ni50Ti50 cantilevers.

Extremely high pitting resistance of NiTi shape memory alloy thin film in simulated body fluids

2008 ◽  
Vol 62 (17-18) ◽  
pp. 2791-2794 ◽  
Author(s):  
T. Shahrabi ◽  
S. Sanjabi ◽  
E. Saebnoori ◽  
Z.H. Barber
Keyword(s):  
Thin Film ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Body Fluids ◽  
Niti Shape Memory Alloy ◽  
Alloy Thin Film ◽  
Simulated Body Fluids

TEM study of chemically converted SiC thin film on nanometer curved Si surface

1993 ◽  
Vol 51 ◽  
pp. 818-819
Author(s):  
A. N. Stepanova ◽  
J. Liu ◽  
K. N. Christensen ◽  
U. T. Son ◽  
K. J. Bachmann ◽  
...  
Keyword(s):  
Thin Film ◽  
Silicon Surface ◽  
Flat Surface ◽  
Mechanical Strain ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Microelectronic Devices ◽  
Vacuum Microelectronic ◽  
Field Emission Cathodes

Silicon whiskers with nanometer curvature have a variety of applications such as probes in STM and AFM, or field emission cathodes for vacuum microelectronic devices. For these and other applications it is essential to stabilize the sharply curved silicon surface during usage. Carburization of the silicon surface seems to be a very suitable solution to this problem, since SiC crystals have excellent physical properties and are chemically quite inert. There have been a number of reports of the carburization of flat surface silicon wafers by chemical reaction using both CVD and MBE methods. However, to carburize while maintaining a very sharp silicon tip is extremely difficult. It is also desirable to carburize only a very thin layer, so as to avoid excessive mechanical strain arising from the large difference (∼20%) in lattice parameters.Our carburizations were carried out in a turbo-pumped ultra-high vacuum system. The silicon specimens were oxidation sharpened and cleaned in a buffered HF solution.

Excimer laser annealing of NiTi shape memory alloy thin film

2003 ◽  
Author(s):  
Qiong Xie ◽  
Weimin Huang ◽  
Ming Hui Hong ◽  
Wendong Song ◽  
Tow Chong Chong
Keyword(s):  
Thin Film ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Excimer Laser ◽  
Laser Annealing ◽  
Niti Shape Memory Alloy ◽  
Alloy Thin Film ◽  
Excimer Laser Annealing

Response of Optical Fiber Bragg Sensors With a Thin Film Shape Memory Alloy Coating

2008 ◽  
Author(s):  
K. P. Mohanchadra ◽  
Michael C. Emmons ◽  
Sunny Karnani ◽  
Gregory P. Carman ◽  
W. Lance Richards
Keyword(s):  
Thin Film ◽  
Shape Memory Alloy ◽  
Optical Fiber ◽  
Shape Memory ◽  
Alloy Coating ◽  
Niti Shape Memory Alloy ◽  
Alloy Thin Film ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Transformation Temperatures

This paper describes the sputter deposition and characterization of nickel titanium (NiTi) shape memory alloy thin film onto the surface of an optical fiber Bragg sensor. The NiTi coating uniformity, crystallinity and transformation temperatures are measured using scanning electron microsocopy, x-ray diffraction and differential scanning calorimetry respectively. The strain in the optical fiber is measured using centroid calculation of wavelength shifts. Results show distinct and abrupt changes in the optical fiber signal with the four related transformation temperatures represented by the austenite-martensite forward and reverse phase transformations. These tests demonstrate a coupling present between optical energy and thermal energy, i.e. a modified multiferroic material.

Particle radiation effects on shape memory alloy couplers for ultra-high vacuum sealing: a preliminary study

2019 ◽  
Vol 28 (8) ◽  
pp. 085023
Author(s):  
F Niccoli ◽  
C Garion ◽  
C Maletta ◽  
C Cangialosi ◽  
A Infantino ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Radiation Effects ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Particle Radiation ◽  
Vacuum Sealing ◽  
Preliminary Study

Sputter-Deposited Shape-Memory Alloy Thin Films: Properties and Applications

MRS Bulletin ◽  
2002 ◽  
Vol 27 (2) ◽  
pp. 111-114 ◽  
Author(s):  
Akira Ishida ◽  
Valery Martynov
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Microelectromechanical Systems ◽  
Sputter Deposition ◽  
Bulk Materials ◽  
Shape Memory Actuators ◽  
Sputter Deposited ◽  
Memory Characteristics

AbstractShape-memory alloy (SMA) thin films formed by sputter deposition have attracted considerable attention in the last decade. Current intensive research demonstrates that unique fine microstructures are responsible for the superior shape-memory characteristics observed in thin films as compared with bulk materials. Simultaneously, much effort has been undertaken to develop and fabricate micro devices actuated by SMA thin films. This article reviews the research to date on shape-memory behavior and the mechanical properties of SMA thin films in connection with their peculiar microstructures. Promising applications such as microvalves are demonstrated, along with a focused discussion on process-related problems. All of the results indicate that thin-film shape-memory actuators are ready to contribute to the development of microelectromechanical systems.

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