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Bending, Deformation and Thermomechanical Behavior

Bending Behavior of Conductive Polymers: Electroactive conducting polymers are known for their unique redox-state dependent mechanical responses that can be easily controlled by various stimuli. When electrons are donated to or removed from the polymer chains, the polymer conformations are subjected to considerable relaxations and at the same time the compensating ionic species are inserted or extracted. These combined electronic and ionic changes give rise to the macroscopic polymer volume variations. Featured by their characteristic low activation voltage, large stress and strain, and capability of operating in liquid electrolytes including the physiological salt solution, conducting polymers are promising materials for artificial muscles. In this research, we focus on actuator applications of the conducting polymers, where the volume change relies on the ions and solvent migration. Although electrostatic and piezoelectric materials have major technological importance for the direct conversion of electrical energy to mechanical energy in actuators, conducting polymers could provide attractive features that function more analogously to natural muscles.

Representative Publications (#denotes graduate students/postdocs supervised by X. Zhang; *denotes corresponding author by X. Zhang; +denotes contributed equally.)

P. Du#, X. Lin, and X. Zhang*, "A Multilayer Bending Model for Conducting Polymer Actuators," Sensors and Actuators A: Physical, 2010, 163(1): 240-246. [DOI]


Deformation and Thermomechanical Behavior of Multilayer Microcantilevers: Multilayer cantilever structures are widely applied in micro/nanosystems. Unfortunately, the manufacturability, planarity and reliability have been always inadequate. While much of the understanding regarding the thermomechanical behavior of layered systems derives from experiences in microelectronics, significant differences exist for many MEMS applications, and these must be well understood to optimize the design of reliable micro/nanosystems. The overall goal of this research is to understand the deformation mechanisms in MEMS thin film materials, relate these behaviors to the design and analysis of MEMS, and apply these principles to improve the performance of the devices in the sub-micron scale. This research will lead to a better understanding of the relationship between structures and properties of free-standing thin film materials, which will potentially have a broader impact on microelectronics and MEMS-based structures and devices.

Representative Publications (#denotes graduate students/postdocs supervised by X. Zhang; *denotes corresponding author by X. Zhang; +denotes contributed equally.)

I-K Lin#, X. Zhang*, Y. Zhang*, "Inelastic Deformation of Bilayer Microcantilevers with Nanoscale Coating," Sensors and Actuators A: Physical, 2011, 168(1): 1-9. [DOI]

I-K Lin#, X. Zhang*, Y. Zhang*, "Thermomechanical Behavior and Microstructural Evolution of SiNx/Al Bimaterial Microcantilevers," Journal of Micromechanics and Microengineering, 2009, 19(8): 085010(10pp). [DOI]

I-K Lin#, Y. Zhang*, X. Zhang*, "The Deformation of Microcantilever-Based Infrared Detectors During Thermal Cycling," Journal of Micromechanics and Microengineering, 2008, 18(7): 075012(9pp). [DOI]

S. Huang#, H. Tao#, I-K Lin#, X. Zhang*, "Development of Double-Cantilever Infrared Detectors: Fabrication, Curvature Control and Demonstration of Thermal Detection," Sensors and Actuators A: Physical, 2008, 145-146: 231-240. [DOI]

S. Huang# and X. Zhang*, "Study of Gradient Stress in Bimaterial Cantilever Structures for Infrared Applications," Journal of Micromechanics and Microengineering, 2007, 17(7): 1211-1219. [DOI]

S. Huang# and X. Zhang*, "Gradient Residual Stress Induced Elastic Deformation of Multilayer MEMS Structures," Sensors and Actuators A: Physical, 2007, 134(1): 177-185. [DOI]

S. Huang#, B. Li, X. Zhang*, "Elimination of Stress-Induced Curvature in Microcantilever Infrared Focal Plane Arrays," Sensors and Actuators A: Physical, 2006, 130-131: 331-339. [DOI]

S. Huang# and X. Zhang*, "Extension of the Stoney Formula for Film-Substrate Systems with Gradient Stress for MEMS Applications," Journal of Micromechanics and Microengineering, 2006, 16(2): 382-389. [DOI]

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