Shape Memory Alloy Bimorph Microactuators by Lift-Off Process

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Hao Sun ◽  
Jianjun Luo ◽  
Zhongjing Ren ◽  
Ming Lu ◽  
Dmytro Nykypanchuk ◽  
...  
Keyword(s):  
Thin Films ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Precision ◽  
Sem Images ◽  
Element Analysis ◽  
Heating And Cooling ◽  
Finite Element Analysis Simulation ◽  
Micro Actuators ◽  
Lift Off

Abstract This study aims to develop a new fabrication process to create high-precision patterned shape memory alloy (SMA) bimorph micro-actuators by the e-beam evaporation technique. To examine the effect of the annealing process on nitinol (NiTi) thin film characteristics, the as-deposited and annealed NiTi thin films are, respectively, investigated. X-ray diffraction (XRD) results demonstrate the crystallization of NiTi thin films after annealing at 600 °C. The transformation behaviors of NiTi thin films during heating and cooling are studied using the differential scanning calorimeter (DSC). Furthermore, scanning electron microscopy (SEM) images indicate that SMA bimorph micro-actuators with high-precision features can be fabricated by the lift-off process, without any wet or dry etching procedures, and their thermomechanical behaviors are experimentally verified by comparing them with that of finite element analysis simulation results.

scholarly journals New Insights Into Shape Memory Alloy Bimorph Actuators Formed by Electron Beam Evaporation

2018 ◽  
Author(s):  
Hao Sun ◽  
Jianjun Luo ◽  
Ming Lu ◽  
Dmytro Nykypanchuk ◽  
Yong Shi
Keyword(s):  
Electron Beam ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Precision ◽  
Deposition Rate ◽  
Annealing Process ◽  
Element Analysis ◽  
Finite Element Analysis Simulation ◽  
Lift Off ◽  
Beam Deposition

In order to create shape memory alloy (SMA) bimorph microactuators with high-precision features, a novel fabrication process combined with electron beam (E-beam) evaporation, lift-off resist and isotropic XeF2 dry etching method was developed. To examine the effect of E-beam deposition and annealing process on nitinol (NiTi) characteristics, the NiTi thin film samples with different deposition rate and overflow conditions during annealing process were investigated. With the characterizations using scanning electron microscope and x-ray diffraction, the results indicated that low E-beam deposition rate and argon employed annealing process could benefit the formation of NiTi crystalline structure. Besides, SMA bimorph microactuators with high-precision features as small as 5 microns were successfully fabricated. Furthermore, the thermomechanical performance was experimentally verified and compared with finite element analysis simulation results.

Quantitative phase transformation behavior in TiNi shape memory alloy thin films

2004 ◽  
Vol 19 (10) ◽  
pp. 2822-2833 ◽  
Author(s):  
Bo-Kuai Lai ◽  
H. Kahn ◽  
S.M. Phillips ◽  
Z. Akase ◽  
A.H. Heuer
Keyword(s):  
Thin Films ◽  
Shape Memory Alloy ◽  
Residual Stresses ◽  
Shape Memory ◽  
Microelectromechanical Systems ◽  
Rietveld Analysis ◽  
Phase Fraction ◽  
Temperature Hysteresis ◽  
Noticeable Effect ◽  
Heating And Cooling

Phase transformations in near-equiatomic TiNi shape memory alloy thin films were studied, and the phase fraction evolutions were quantitatively correlated to the stress and resistivity of the films. TiNi thin films with compositions of 50.1, 51.1, and 51.7 at.% Ti all exhibited transformation temperatures between 65 and 100 °C, low residual stresses at room temperature (RT), and high recoverable stresses, thus making them suitable for microactuators in microelectromechanical systems. Low residual stresses at RT, less than 50 MPa, can be obtained even when only a small quantity of martensite, less than 30%, is present. Phase fraction evolution during complete thermal cycles (heating and cooling) was studied using elevated temperature x-ray diffraction, combined with quantitative Rietveld analysis. R-phase always appeared in these near-equiatomic TiNi thin films during cooling but did not have a noticeable effect on the stress–temperature hysteresis curves, which mainly depend on the phase fraction evolution of martensite. On the other hand, the occurrence of R-phase determined the variation of film resistivity. Martensite, austenite, and R-phase coexisting within a single grain were observed using transmission electron microscopy.

Nanoindentation of binary and ternary Ni–Ti-based shape memory alloy thin films

2008 ◽  
Vol 202 (13) ◽  
pp. 3115-3120 ◽  
Author(s):  
A.J. Muir Wood ◽  
S. Sanjabi ◽  
Y.Q. Fu ◽  
Z.H. Barber ◽  
T.W. Clyne
Keyword(s):  
Thin Films ◽  
Shape Memory Alloy ◽  
Shape Memory

Experimental Validation and Numerical Simulation of Shape Memory Flat Wire Actuators

2014 ◽  
Author(s):  
Alexander Czechowicz ◽  
Sven Langbein
Keyword(s):  
Shape Memory Alloy ◽  
Boundary Conditions ◽  
Shape Memory ◽  
Smart Materials ◽  
Empirical Data ◽  
Dynamic Properties ◽  
Fatigue Behavior ◽  
Different Boundary Conditions ◽  
Heating And Cooling ◽  
Actual Shape

Shape memory alloys (SMA) are thermally activated smart materials. Due to their ability to change into a previously imprinted actual shape through the means of thermal activation, they are suitable as actuators for mechatronical systems. Despite of the advantages shape memory alloy actuators provide, these elements are only seldom integrated by engineers into mechatronical systems. Reasons are the complex characteristics, especially at different boundary conditions and the missing simulation- and design tools. Also the lack of knowledge and empirical data are a reason why development projects with shape memory actuators often lead to failures. This paper deals with the dynamic properties of SMA-actuators (Shape Memory Alloy) — characterized by their rate of heating and cooling procedures — that today can only be described insufficiently for different boundary conditions. Based on an analysis of energy fluxes into and out of the actuator, a numerical model of flat-wire used in a bow-like structure, implemented in MATLAB/SIMULINK, is presented. Different actuation parameters, depending on the actuator-geometry and temperature are considered in the simulation in real time. Additionally this publication sums up the needed empirical data (e.g. fatigue behavior) in order to validate the numerical two dimensional model and presents empirical data on SMA flat wire material.

The effects of ion irradiation on NiTi shape memory alloy thin films

1999 ◽  
Vol 342 (1-2) ◽  
pp. 67-73 ◽  
Author(s):  
Florent Goldberg ◽  
Émile J. Knystautas
Keyword(s):  
Thin Films ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Ion Irradiation ◽  
Niti Shape Memory Alloy

Magnetic phases in thin films of Ni–Fe(Co)–Ga ferromagnetic shape memory alloy

2017 ◽  
Vol 50 (45) ◽  
pp. 455006 ◽  
Author(s):  
V A Chernenko ◽  
I R Aseguinolaza ◽  
V Golub ◽  
O Y Salyuk ◽  
J M Barandiarán
Keyword(s):  
Thin Films ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Ferromagnetic Shape Memory Alloy ◽  
Magnetic Phases ◽  
Ferromagnetic Shape Memory
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