Viscoelastic Characterization and Modeling of Polymer Transducers for Biological Applications

• Published in: Journal of microelectromechanical systems Vol. 18; no. 5; pp. 1087 - 1099
• Main Authors: LIN, I-Kuan, OU, Kuang-Shun, LIAO, Yen-Ming, YAN LIU, CHEN, Kuo-Shen, XIN ZHANG
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.10.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Biological materials; Biological system modeling; Cellular; Cellular traction force; Constitutive relationships; Converting; Deformable models; Elasticity; Exact sciences and technology; Finite element analysis; Finite element method; finite-element analysis (FEA); Force measurement; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mathematical models; Mechanical factors; Mechanical instruments, equipment and techniques; Micromechanical devices and systems; Nanobioscience; Physics; polydimethylsiloxane (PDMS); Polymers; Silicone resins; Studies; Traction force; transducer; Transducers; Viscoelasticity; Viscosity; Constitutive equation; Nanohardness; Dimethylsiloxane polymer; Viscoelasticity; Force measurement; finite-element analysis (FEA); transducer; polydimethylsiloxane (PDMS); Nanoindentation; Mechanical properties; Mechanical tests; Nanostructures; Indentation; Microhardness; Finite element method; Vibrations; Dynamic mechanical properties; Ambient temperature; Cardiomyocyte; Cellular traction force; Modelling; Microelectromechanical device
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2009.2029166

Polydimethylsiloxane (PDMS) is an important polymeric material widely used in bio-MEMS devices such as micropillar arrays for cellular mechanical force measurements. The accuracy of such a measurement relies on choosing an appropriate material constitutive model for converting the measured structural deformations into corresponding reaction forces. However, although PDMS is a well-known viscoelastic material, many researchers in the past have treated it as a linear elastic material, which could result in errors of cellular traction force interpretation. In this paper, the mechanical properties of PDMS were characterized by using uniaxial compression, dynamic mechanical analysis, and nanoindentation tests, as well as finite element analysis (FEA). A generalized Maxwell model with the use of two exponential terms was used to emulate the mechanical behavior of PDMS at room temperature. After we found the viscoelastic constitutive law of PDMS, we used it to develop a more accurate model for converting deflection data to cellular traction forces. Moreover, in situ cellular traction force evolutions of cardiac myocytes were demonstrated by using this new conversion model. The results presented by this paper are believed to be useful for biologists who are interpreting similar physiological processes.