Shape memory microvalves based on thin films or rolled sheets

Kohl, Manfred; Dittmann, D.; Quandt, Eckhard; Winzek, Bernhard; Miyazaki, S.; Allen, D.M.

doi:10.1016/s0921-5093(99)00416-5

Cited by 81 publications

(37 citation statements)

References 5 publications

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“…Thus, actuators with two-dimensionalshape such as diaphragms and multi-directional beam-cantilever type actuators have been fabricated. [5][6][7][8][9][10] The coldrolling process is industrially advantageous to fabricate binary Ti-Ni alloy thin plates in a limited compositional range. On the other hand, by using the melt-spinning technique, thinner Ti-Ni ribbons such as 15 micrometers in thickness can be fabricated in a wide compositional range as well as ternary Ti-Ni base alloys.…”

Section: Introductionmentioning

confidence: 99%

Texture and Microstructure of Ti-Ni Melt-Spun Shape Memory Alloy Ribbons

2004

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The shape memory behavior, texture and microstructure were studied for Ti-Ni ribbons fabricated by a melt-spinning method where the Ni contents were designed to be 49.0 at%, 50.0 at% and 51.0 at%. The texture of the parent B2 phase was determined by X-ray diffraction pole figures. A strong h100i fiber texture was found in both pole figures and orientation distribution functions (ODF). TEM observation revealed that all the ribbons are fully crystallized and that disk-type precipitates of about 10 nm in length locate on {100} of B2 phase uniformly. The thermal cyclic tests under various constant stresses showed shape recoverable strains exceeding 5% and critical stresses for plastic deformation being higher than 400 MPa for Ti-49.0 at%Ni and Ti-50.0 at%Ni as-spun ribbons. These excellent shape memory characteristics of the melt-spun ribbons are due to the formation of these disk-type precipitates. In addition, Ti 2 Ni precipitates of 25 nm in diameter appeared along grain boundaries of Ti-51.0 at%Ni as-spun ribbon. Since the Ni content of the matrix is condensed due to the formation of Ti 2 Ni precipitates, no shape memory effect was observed in Ti-51.0 at%Ni as-spun ribbon under the experimental conditions.

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Section: Introductionmentioning

confidence: 99%

Texture and Microstructure of Ti-Ni Melt-Spun Shape Memory Alloy Ribbons

2004

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“…Moreover, thin-film SMAs in the form of membranes have been considered for micropumps [11,74,119] and microvalves [57,58] that generate large pressures and pumping rates. In [98], a thin-film SMA membrane is used in a prototype compact hybrid actuator to reach drive frequencies of 100 Hz and output forces exceeding 100 N. In [104], the change in optical reflectivity from austenite to martensite is utilized to fabricate a membrane-based light-valve.…”

Section: Applicationsmentioning

confidence: 99%

A homogenized free energy model for hysteresis in thin-film shape memory alloys

Massad

Smith

2005

Thin Solid Films

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Thin-film shape memory alloys (SMAs) have become excellent candidates for microactuator fabrication in MEMS due to their capability to achieve very high work densities, produce large deformations, and generate high stresses. In general, the material behavior of SMAs is nonlinear and hysteretic. To achieve the full potential of SMA actuators, it is necessary to develop models that characterize the nonlinearities and hysteresis inherent to the constituent materials. We develop a model that quantifies the nonlinearities and hysteresis inherent to SMAs. The model is based on free energy principles combined with stochastic homogenization techniques. The fully thermomechanical model predicts rate-dependent, polycrystalline SMA behavior, and it accommodates heat transfer issues pertinent to thin-film SMAs. We illustrate aspects of the model through comparison with thin-film SMA superelastic and shape memory effect hysteresis data.

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“…[4][5][6][7][8][9] TiNibased thin films provide a large energy density, higher frequency response and long working life time at the microscale. Also they can be engineered into structures of micro-size dimensions, patterned with standard lithographic techniques and fabricated in batch.…”

Section: Introductionmentioning

confidence: 99%

A TiNiCu Thin Film Micropump Made by Magnetron Co-Sputtered Method

Zhang

Qiu

2006

Mater. Trans.

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Thin film SMAs have the potential to became a primary actuating mechanism for micropumps. In this study, a micropump driven by TiNiCu shape memory thin film is designed and fabricated. The micropump is composed of a TiNiCu/Si bimorph driving membrane, a pump chamber and two inlet and outlet check valves. The property of TiNiCu films and driving capacity of TiNiCu/Si bimorph driving membrane are investigated. The film surface shows a smooth and featureless morphology without any cracks, and the hysteresis width ÁT of TiNiCu film is about 9 C. By using the recoverable force of TiNiCu thin film and biasing force of silicon membrane, the actuation diaphragm realizes reciprocating motion effectively. Experimental results show that the micropump driving by TiNiCu film has good performance, such as high pumping yield, high working frequency, stable driving capacity, and long fatigue life time.

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Shape memory microvalves based on thin films or rolled sheets

Cited by 81 publications

References 5 publications

Texture and Microstructure of Ti-Ni Melt-Spun Shape Memory Alloy Ribbons

Texture and Microstructure of Ti-Ni Melt-Spun Shape Memory Alloy Ribbons

A homogenized free energy model for hysteresis in thin-film shape memory alloys

A TiNiCu Thin Film Micropump Made by Magnetron Co-Sputtered Method

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