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

Research output: Contribution to journalArticlepeer-review

43 Citations (SciVal)


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
JournalEPL (Europhysics Letters)
Issue number5
Publication statusPublished - 12 Sept 2012


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