Abstract
The thermal actuator presented in this paper consists of two symmetrically V-shaped beam stacks, where each stack consists of six beams in parallel. The stacks are coupled facing each other and slightly shifted along the mirror axis. Both stacks are connected to a lever beam and fixed at four anchor regions to the substrate. Due to the difference in the coefficient of thermal expansion of the material of the beams and the one of the substrate, the tip of the lever moves perpendicular to the mirror axis. The device is fabricated from galvanic deposited nickel on a silicon substrate. Finite element simulations were carried out to optimize the design with respect to the sensitivity and the maximum mechanical stress. The stress needs to be lower than the yield strength of the material. Otherwise, plastic deformations of the beams would lead to irreversible deflections of the beam tip. This limits the overall sensitivity of the design. First results of the device with 400 μm long bent beams show a linear behavior and a sensitivity of 0.5 μm/K and forces of 66 μN/K for a temperature range of −30 °C up to +40 °C.
Similar content being viewed by others
References
Ando B, Baglio S, Savalli N, Trigona C (2011) Cascaded triple-bent-beam MEMS sensor for contactless temperature measurements in nonaccessible environments. IEEE Trans Instrum Meas 60:1348–1357
Cowen A, Mahadevan R, Johnson S, Hardy B (2009) MetalMUMPs Design Handbook, Rev.3.0. MEMScap
Daneshmand M, Fouladi S, Mansour RR, Lisi M, Stajcer T (2009) Thermally-actuated latching RF MEMS switch. In: Proceeding of IEEE MTT-S International Microwave Symposium Digest 2009. MTT’09, pp 1217–1220
Enikov E, Kedar S, Lazarov K (2005) Analytical model for analysis and design of V-shaped thermal microactuators. J Microelectromech Syst 14:788–798
Guan C, Zhu Y (2010) An electrothermal microactuator with z-shaped beams. J Micromech Microeng 20:085014
Hammacher J, Fuelle A, Flaemig J, Saupe J, Loechel B, Grimm J (2008) Stress engineering and mechanical properties of SU-8-layers for mechanical applications. Microsyst Technol 14:1515–1523
He S, Chang JS, Li L, Ho H (2009) Characterization of Young’s modulus and residual stress gradient of MetalMUMPs electroplated nickel film. Sens Actuators A 154:149–156
Khazaai JJ, Qu H (2012) Electro-thermal MEMS switch with latching mechanism: design and characterization. IEEE Sens J 12:2830–2838
Lai Y, McDonald J, Kujath M, Hubbard T (2003) Force, deflection and power measurements of toggled microthermal actuators. J Micromech Microeng 14(1):49
Lee C, Wu C-Y (2005) Study of electrothermal V-beam actuators and latched mechanism for optical switch. J Micromech Microeng 15:11–19
Lide DR (2008) CRC handbook of chemistry and physics: a ready-reference book of chemical and physical data: 2008–2009. CRC Press, Boca Raton; London; New York
Mastrangelo CH (1993a) Mechanical stability and adhesion of microstructures under capillary forces part I: basic theory. J Microelectromech Syst 2(1):33–43
Mastrangelo CH (1993b) Mechanical stability and adhesion of microstructures under capillary forces part II: experiments. J Microelectromech Syst 2(1):44–55
Nguyen N-T, Ho S-S, Low CL-N (2004) A polymeric microgripper with integrated thermal actuators. J Micromech Microeng 14:969–974
Que L, Park J-S, Gianchandani YB (1999) Bent-beam electro-thermal actuators for high force applications. In: Proceeding of Twelfth IEEE International Conference on Micro Electro Mechanical Systems, MEMS’99, pp 31–36
Que L, Park J-S, Gianchandani YB (2001) Bent-beam electrothermal actuators-part I: single beam and cascaded devices. J Microelectromech Syst 10(2):247–254
Schoeberle B, Wendlandt M, Hierold C (2008) Long-term creep behavior of SU-8 membranes: application of the time-stress superposition principle to determine the master creep compliance curve. Sens Actuators A 142:242–249
Steiner H, Keplinger F, Hortschitz W, Stifter M (2012) The non-linear thermal behavior of SU-8. In: Proceeding of 35th International Spring Seminar on Electronics Technology (ISSE), 2012, pp 450–454
Touloukian YS, Kirby RK, Taylor RE, Desai PD (1975) Thermophysical properties of matter—the TPRC data series, vol 12. Thermal Expansion Metallic Elements and Alloys, Defense Technical Information Center, USA
Yang Y-S, Lin Y-H, Hu Y-C, Liu C-H (2009) A large-displacement thermal actuator designed for MEMS pitch-tunable grating. J Micromech Microeng 19:015001
Acknowledgments
This project was supported by the Austrian research promotion agency (Contactless (RFID) Sensing Project, Project Nr. 830604).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Steiner, H., Hortschitz, W., Stifter, M. et al. Thermal actuators featuring large displacements for passive temperature sensing. Microsyst Technol 20, 551–557 (2014). https://doi.org/10.1007/s00542-013-1990-x
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00542-013-1990-x