Induced-strain multimorphs for microscale sensory actuation design

The paper proposes an analytic model that evaluates the levels of actuation and sensing by microbenders formed of several sandwiched layers (multimorphs) of active/sensitive materials such as piezoelectric (PZT) and shape memory alloys (SMA) interspersed with structural materials which only react to thermal variations. The model is generic, such that any type of induced strain can be incorporated into it, and its prediction gives the deformed (bent) shape, the corresponding tip bending moment, as well as the position of the neutral axis (NA) and the composite bending rigidity. The generic model reduces to the well-known Timoshenko 'bi-metal thermostat' model in the case of two layers of which one is thermally heated. Finite element simulation produces results that are very close to the analytic model predictions for a three-layer (trimorph) bender when all layers are heated. Concrete examples are further studied that can be encountered in small-scale (MEMS) applications, such as an antisymmetric PZT trimorph with either unilateral actuation and sensing or just antisymmetric actuation, a SMA-actuated bimorph and a hybrid PZT–SMA trimorph that can act as a simultaneous sensory actuator microdevice. Numerical simulations are performed for all examples in order to highlight trends in performance as a function of the microcantilever geometry.

[1]  S. Torquato,et al.  Design of smart composite materials using topology optimization , 1999 .

[2]  Vijay K. Varadan,et al.  A review and critique of theories for piezoelectric laminates , 1999 .

[3]  Victor Giurgiutiu,et al.  Theoretical and experimental investigation of magnetostrictive composite beams , 2001 .

[4]  Philippe Gaucher.  Piezoelectric and electrostrictive bimorph actuators and sensors for smart microsystems , 1996, Other Conferences.

[5]  S. Timoshenko,et al.  Analysis of Bi-Metal Thermostats , 1925 .

[6]  E. Crawley,et al.  Use of piezoelectric actuators as elements of intelligent structures , 1987 .

[7]  David Harrison,et al.  Shape memory alloy actuators for active disassembly using ‘smart’ materials of consumer electronic products , 2002 .

[8]  D. Lagoudas,et al.  Modeling of thin layer extensional thermoelectric SMA actuators , 1998 .

[9]  R. B. Marcus,et al.  Thermally actuated microprobes for a new wafer probe card , 1999 .

[10]  Oliver Paul,et al.  Thermally actuated CMOS micromirrors , 1995 .

[11]  M. Weinberg.  Working equations for piezoelectric actuators and sensors , 1999 .

[12]  Manfred Kohl,et al.  A novel actuation mechanism on the basis of ferromagnetic SMA thin films , 2004 .

[13]  T. Low,et al.  Modeling of a three-layer piezoelectric bimorph beam with hysteresis , 1995 .

[14]  Nagi G. Naganathan,et al.  Study of induced strain transfer in piezoceramic smart material systems , 1999 .

[15]  A. Pisano,et al.  Modeling and optimal design of piezoelectric cantilever microactuators , 1997 .

[16]  W. J. Karl,et al.  Cantilever unified theory and optimization for sensors and actuators , 2000 .

[17]  Amâncio Fernandes,et al.  Analytical and numerical approaches to piezoelectric bimorph , 2003 .

[18]  Jan G. Smits,et al.  The constituent equations of piezoelectric bimorphs , 1991 .

[19]  Nicolae Lobontiu,et al.  Achieving Maximum Tip Displacement during Resonant Excitation of Piezoelectrically Actuated Beams , 1999 .

[20]  Wen Hwa Chu,et al.  Analysis of tip deflection and force of a bimetallic cantilever microactuator , 1993 .

[21]  Roshdy George S. Barsoum.  Active materials and adaptive structures , 1997 .

[22]  J.G. Smits,et al.  The constituent equations of piezoelectric heterogeneous bimorphs , 1991, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[23]  Teodor Gotszalk,et al.  Thermally driven micromechanical beam with piezoresistive deflection readout , 2003 .

[24]  P. Renaud,et al.  Thermally actuated optical microscanner with large angle and low consumption , 1999 .

[25]  J. Susini,et al.  Compact active/adaptive x‐ray mirror: Bimorph piezoelectric flexible mirror , 1995 .

[26]  Donald Ricketts,et al.  Transverse vibrations of composite piezoelectric polymer plates , 1985 .