Surface imaging using holographic optical tweezers
- 7 June 2011
- journal article
- Published by IOP Publishing in Nanotechnology
- Vol. 22 (28), 285503
- https://doi.org/10.1088/0957-4484/22/28/285503
Abstract
We present an imaging technique using an optically trapped cigar-shaped probe controlled using holographic optical tweezers. The probe is raster scanned over a surface, allowing an image to be taken in a manner analogous to scanning probe microscopy (SPM), with automatic closed loop feedback control provided by analysis of the probe position recorded using a high speed CMOS camera. The probe is held using two optical traps centred at least 10 µm from the ends, minimizing laser illumination of the tip, so reducing the chance of optical damage to delicate samples. The technique imparts less force on samples than contact SPM techniques, and allows highly curved and strongly scattering samples to be imaged, which present difficulties for imaging using photonic force microscopy. To calibrate our technique, we first image a known sample--the interface between two 8 µm polystyrene beads. We then demonstrate the advantages of this technique by imaging the surface of the soft alga Pseudopediastrum. The scattering force of our laser applied directly onto this sample is enough to remove it from the surface, but we can use our technique to image the algal surface with minimal disruption while it is alive, not adhered and in physiological conditions. The resolution is currently equivalent to confocal microscopy, but as our technique is not diffraction limited, there is scope for significant improvement by reducing the tip diameter and limiting the thermal motion of the probe.Keywords
This publication has 27 references indexed in Scilit:
- High-speed atomic force microscopy for nano-visualization of dynamic biomolecular processesProgress in Surface Science, 2008
- A new detection system for extremely small vertically mounted cantileversNanotechnology, 2008
- Nanomechanical analysis of cells from cancer patientsNature Nanotechnology, 2007
- Breaking the speed limit with atomic force microscopyNanotechnology, 2006
- Scanning Probe Evolution in BiologyScience, 2003
- An overview of the biophysical applications of atomic force microscopyBiophysical Chemistry, 2003
- Imaging of lactic acid bacteria with AFM—elasticity and adhesion maps and their relationship to biological and structural dataUltramicroscopy, 2003
- Dynamic atomic force microscopy methodsSurface Science Reports, 2002
- Defects and their charge imaging on semiconductor surfaces by noncontact atomic force microscopy and spectroscopyJournal of Crystal Growth, 2000
- Detection and localization of individual antibody-antigen recognition events by atomic force microscopy.Proceedings of the National Academy of Sciences, 1996