| 1. |
- Clausi, Donato, et al.
(författare)
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Design and wafer-level fabrication of SMA wire microactuators on silicon
- 2010
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Ingår i: Journal of microelectromechanical systems. - : IEEE Press. - 1057-7157 .- 1941-0158. ; 19:4, s. 982-991
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on the fabrication of microactuators through wafer-level integration of prestrained shape memory alloy wires to silicon structures. In contrast to previous work, the wires are strained under pure tension, and the cold-state reset is provided by single-crystalline silicon cantilevers. The fabrication is based on standard microelectromechanical systems manufacturing technologies, and it enables an actuation scheme featuring high work densities. A mathematical model is discussed, which provides a useful approximation for practical designs and allows analyzing the actuators performance. Prototypes have been tested, and the influence of constructive variations on the actuator behavior is theoretically and experimentally evaluated. The test results are in close agreement with the calculated values, and they show that the actuators feature displacements that are among the highest reported.
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| 2. |
- Clausi, Donato, et al.
(författare)
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Reliability of Silicon Spring-biased SMA Microactuators
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper reports on the performance of Joule-heated shape memory alloy (SMA) microactuators on silicon MEMS.The actuators consist of pre-strained SMA wires connected to micromachined silicon structures by electroplatedfixtures. Response of the actuators upon long term cycling by electrical heating is evaluated. Measurements on a 4.5x 1.6 mm2 footprint device demonstrated excellent stability of the actuator, without any loss of performance over150·103 cycles. These actuators are potentially suited for industrial applications with stringent demands on actuationperformance, reliability, and cost.
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| 3. |
- Clausi, Donato, et al.
(författare)
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Robust actuation of silicon MEMS using SMA wires integrated at wafer-level by nickel electroplating
- 2013
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Ingår i: Sensors and Actuators A-Physical. - : Elsevier BV. - 0924-4247 .- 1873-3069. ; 189, s. 108-116
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on both the wafer-level fixation and electrical connection of pre-strained SMA wires to silicon MEMS using electroplating, and on the fabrication of the first Joule-heated Shape memory alloy (SMA) wire actuators on silicon. The integration method provides both high bond strength and electrical connections in one processing step, and it allows mass production of microactuators having high work density. SEM observation showed an intimate interconnection between the SMA wires and the silicon substrate. The variation of the actuators' performance across the wafer was evaluated on three 4.5 mm × 1.8 mm footprint devices, proving repeatable results. The actuators showed a mean hot state deflection of 536 μm and a mean stroke of 354 μm at a low power consumption (less than 70 mW). One actuator was tested for m150 × 103 cycles, and it demonstrated a highly reliable long-term performance, showing neither material degradation, nor failure of the nickel anchors.
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| 4. |
- Clausi, Donato, et al.
(författare)
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WAFER-LEVEL MECHANICAL AND ELECTRICAL INTEGRATION OF SMA WIRES TO SILICON MEMS USING ELECTROPLATING
- 2011
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Ingår i: 24th IEEE International Conference on Micro Electro Mechanical Systems (IEEE MEMS 2011). - : IEEE conference proceedings. - 9781424496327 ; , s. 1281-1284
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Konferensbidrag (refereegranskat)abstract
- This paper reports on the wafer-level fixation and electrical connection of pre-strained SMA wires on silicon MEMS using electroplating, providing high bond strength and electrical connections in one processing step. The integration method is based on standard micromachining techniques, and it potentially allows mass production of microactuators having high work density. SEM observation showed an intimate interconnection between the SMA wire and the silicon substrate, and destructive testing performed with a shear tester showed a bond strength exceeding 1 N. The first Joule-heated SMA wire actuators on silicon were fabricated and their performance evaluated. Measurements on a 4.5 x 1.8 mm2 footprint device show a 460 μm stroke at low power consumption (70 mW).
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| 5. |
- Gradin, Henrik, et al.
(författare)
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A low-power high-flow shape memory alloy wire gas microvalve
- 2012
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Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics (IOP). - 0960-1317 .- 1361-6439. ; 22:7, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- In this paper the use of shape memory alloy (SMA) wire actuators for high gas flow control is investigated. A theoretical model for effective gas flow control is presented and gate microvalve prototypes are fabricated. The SMA wire actuator demonstrates the robust flow control of more than 1600 sccm at a pressure drop of 200 kPa. The valve can be successfully switched at over 10 Hz and at an actuation power of 90 mW. Compared to the current state-of-the-art high-flow microvalves, the proposed solution benefits from a low-voltage actuator with low overall power consumption. This paper demonstrate that SMA wire actuators are well suited for high-pressurehigh-flow applications.
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