A novel, imaged laser speckle strain gauge is described for directly measuring strain rates in biological tissues. Cortical bone samples were tested in tension in a custom- designed microtensile testing machine. Strain rates were evaluated simultaneously with both the laser speckle strain gauge and contact strain gauges and extensometers. Young's modulus values of the bone samples were estimated using the strain data acquired by all methods. The strain rates and modulus estimates determined through all the methods compared favorably with each other, with the modulus estimates calculated using the speckle data slightly higher than by the other methods (mean of 16.88 GPa for the speckle data vs. 13.4 GPa for the contacting methods). The speckle strain gauge has a strain resolution at least on the order of single microstrain and should prove to be useful in the mechanical evaluation of both native and engineered tissues.

Date Published: 13 June 2000
PDF: 9 pages
Proc. SPIE 3914, Laser-Tissue Interaction XI: Photochemical, Photothermal, and Photomechanical, (13 June 2000); doi: 10.1117/12.388087

Published in SPIE Proceedings Vol. 3914:
Laser-Tissue Interaction XI: Photochemical, Photothermal, and Photomechanical
Jeffrey O. Hollinger D.D.S.; Donald Dean Duncan; Jeffrey O. Hollinger D.D.S.; Donald Dean Duncan; Steven L. Jacques, Editor(s)