
Proceedings Paper
Development and applications of an optical tweezer-based microrheometer: case studies of biomaterials and living cellsFormat | Member Price | Non-Member Price |
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Paper Abstract
The investigation of mechanical properties of living biological cells and biomaterials is challenging because they are
inhomogeneous and anisotropic at microscopic scales, and often time-dependent over a broad time scale. Through three
case studies of biomaterials and living cells, we demonstrate that a novel, oscillating optical tweezer-based imaging
microrheometer developed recently in our laboratory has overcome many technical barriers posed by the complexity of
biological systems. In this paper, we present the working principle, system setup and calibration of the imaging
microrheometer, and report the groundbreaking results of the three applications: gelation dynamics of cross-linkable
hyaluronan acid (HA) hydrogels; Mechanical in-homogeneity and anisotropy in purified microtubule networks; and
effects of drug treatment and temperature variation on the mechanical properties of in vitro human alveolar epithelial
cells. In each case, micro beads inserted in the materials, or attached to the cell membrane were used as probes for
optical trapping. The probe particle was set into a forced harmonic oscillation by oscillating optical tweezers. Position
sensing optics and phase lock-in signal processing allow the determination of the amplitude and phase shift of the
particle motion at high sensitivity. The complex mechanical modulus G* is then calculated from the amplitude and the
phase shift. The rheometer system is capable of measuring dynamic local mechanical moduli in the broad frequency
range of 1.3-1000 Hz at a sampling rate of 2 data point per second across a wide dynamic range (1~20,000 dyne/cm2).
Integration of the rheometer system with spinning disk confocal microscopy enables the study of micromechanical
properties and the microstructure of the sample simultaneously. Combination of dual-axis, piezo-electric activated mirror
and 2-D position sensing detector gives the rheometer system the capability of investigating mechanical anisotropy in
highly structured biological samples.
Paper Details
Date Published: 19 February 2007
PDF: 11 pages
Proc. SPIE 6441, Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues V, 644112 (19 February 2007); doi: 10.1117/12.701324
Published in SPIE Proceedings Vol. 6441:
Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues V
Daniel L. Farkas; Robert C. Leif; Dan V. Nicolau, Editor(s)
PDF: 11 pages
Proc. SPIE 6441, Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues V, 644112 (19 February 2007); doi: 10.1117/12.701324
Show Author Affiliations
Jing Wang, Lehigh Univ. (United States)
Huseyin Yalcin, Lehigh Univ. (United States)
Angela Lengel, Lehigh Univ. (United States)
Huseyin Yalcin, Lehigh Univ. (United States)
Angela Lengel, Lehigh Univ. (United States)
Published in SPIE Proceedings Vol. 6441:
Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues V
Daniel L. Farkas; Robert C. Leif; Dan V. Nicolau, Editor(s)
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