Since the discovery of the trapping nature of laser beam, optical tweezers have been extensively employed to measure various parameters at micro/nano level. Optical tweezers show exceptional sensitivity to weak forces making it one of the most sensitive force measurement devices. In this work, we present a technique to measure the stiffness of a biomaterial at different points. For this purpose, a microparticle stuck at the bottom of the dish is illuminated by the trapping laser and respective QPD signal as a function of the distance between the focus of the laser and the center of the microparticle is monitored. After this, microparticle is trapped and manipulated towards the target biomaterial and when it touches the cell membrane, QPD signal shows variation. By comparing two different QPD signals and measuring the trap stiffness, a technique is described to measure the stiffness of the biomaterial at a particular point. We believe that this parameter can be used as a tool to identify and classify different biomaterials.

Date Published: 22 February 2013
PDF: 8 pages
Proc. SPIE 8595, Colloidal Nanocrystals for Biomedical Applications VIII, 85951G (22 February 2013); doi: 10.1117/12.2005544

Published in SPIE Proceedings Vol. 8595:
Colloidal Nanocrystals for Biomedical Applications VIII
Wolfgang J. Parak; Marek Osinski; Kenji Yamamoto, Editor(s)