Calibration of optically trapped nanotools

Abstract

Holographically trapped nanotools can be used in a novel form of force microscopy. By measuring the displacement of the tool in the optical traps, the contact force experienced by the probe can be inferred. In the following paper we experimentally demonstrate the calibration of such a device and show that its behaviour is independent of small changes in the relative position of the optical traps. Furthermore, we explore more general aspects of the thermal motion of the tool.

Three-Dimensional to Two-Dimensional Crossover in the Hydrodynamic Interactions between Micron-Scale Rods

“…Tracking single rod Brownian motion, we extract an average transverse mobility of 42 µm/s pN. By theoretical predictions, this corresponds to an average rod thickness of about 200 nm, which is well compatible with the nominal pore size (300 nm) used for rod's growth [15]. Turning now to hydrodynamic couplings, the diffusion coefficient of crossed terms directly provides a measure of G xx (d) through (11).…”

“…Optical tweezers can be used to trap and move one dimensional objects [8][9][10]. In particular, holographic optical trapping has been shown to be an ideal tool for full 3D micromanipulation of microrods and nanotubes [11][12][13][14][15]. Such capabilities offer a unique opportunity for trapping and orienting slender bodies in well defined relative configuration, and directly probe their coupled Brownian dynamics.…”

“…However holographic tweezers provide an ideal tool to directly verify our results by trapping and orienting two slender objects in well defined and reproducible relative configurations. We used holographic tweezers to manipulate silica microrods of about 10 µm in length and 150 nm in radius [15]. Multiple optical traps are obtained by shaping an expanded CW laser beam (532 nm) with a spatial light modulator (Holoeye LC-R 2500).…”

Engineering light-matter interaction for emerging optical manipulation applications

“…Another conceptually simple (but technique-intensive) approach is to apply anti-reflection coating onto high-refractive-index microspheres to achieve stability and nanonewton optical forces [61]. These enhancements can be applied when trapping the typically spherical handles of more complex structures such as components in micro-assembly [95] or opticallysteered microtools [96,97]. However, more complex structures will require a different calibration than simple spheres due to difference in their dynamics [97].…”

“…These enhancements can be applied when trapping the typically spherical handles of more complex structures such as components in micro-assembly [95] or opticallysteered microtools [96,97]. However, more complex structures will require a different calibration than simple spheres due to difference in their dynamics [97]. Microfabrication is also advancing developments in optically driven micromotors [28-30, 98, 99].…”