(a) The optically trapped bead coated with receptor molecules is brought close to a bacterium stuck on the surface of the large bead. (b) The bond is loaded by moving the piezo stage by a distance xlb and the resulting displacement of the small bead, xsb, is measured by the deflection of the probe beam. (c) The force applied to the bond as a function of time is determined from the movement of the small bead and the measured trap stiffness. This measurement suggests that a single bond was formed and that it was broken at an applied force of approximately 16 pN.
Reprinted from Fällman et al., Biosens. Bioelectron. 19, 1429–37, copyright 2004, with permission from Elsevier.
Fig. 14.3 — Measurement of bacterial adhesion forces