Force sensing with a shaped dielectric micro-tool

D. B. Phillips*, S. H. Simpson, J. A. Grieve, R. Bowman, G. M. Gibson, M. J. Padgett, J. G. Rarity, S. Hanna, M. J. Miles, D. M. Carberry

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

39 Citations (Scopus)


We analyse the thermal motion of a holographically trapped non-spherical force probe, capable of interrogating arbitrary samples with nanometer resolution. High speed video stereo-microscopy is used to track the translational and rotational coordinates of the micro-tool in three dimensions, and the complete 6×6 stiffness matrix for the system is determined using equipartition theorem. The Brownian motion of the extended structure is described in terms of a continuous distribution of thermal ellipsoids. A centre of optical stress, at which rotational and translational motion is uncoupled, is observed and controlled. Once calibrated, the micro-tool is deployed in two modes of operation: as a force sensor with <150 femto-Newton sensitivity, and in a novel form of photonic force microscopy.

Original languageEnglish
Article number58004
Issue number5
Publication statusPublished - Sep 2012

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    Phillips, D. B., Simpson, S. H., Grieve, J. A., Bowman, R., Gibson, G. M., Padgett, M. J., Rarity, J. G., Hanna, S., Miles, M. J., & Carberry, D. M. (2012). Force sensing with a shaped dielectric micro-tool. EPL, 99(5), [58004].