Optically Fabricated and Driven Micromachines

Theodor Asavei (2010). Optically Fabricated and Driven Micromachines PhD Thesis, School of Mathematics & Physics, The University of Queensland.

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Author Theodor Asavei
Thesis Title Optically Fabricated and Driven Micromachines
School, Centre or Institute School of Mathematics & Physics
Institution The University of Queensland
Publication date 2010-10
Thesis type PhD Thesis
Supervisor Dr. Timo Nieminen
Prof. Norman Heckenberg
Prof. Halina Rubinsztein-Dunlop
Total pages 154
Total colour pages 22
Total black and white pages 132
Subjects 02 Physical Sciences
Abstract/Summary Two-photon photopolymerization of optically curable resins is a powerful tool for fabricating micrometer-sized objects of potentially any shape in three dimensions. This method relies on the fact that certain liquid organic resins can be hardened by exposure to UV light. After full cure, they have very good transmission over a wide spectral range from near UV to short-wavelength infrared. Due to their transparency, these objects are ideal for optical trapping experiments. By using an infrared femtosecond pulsed laser instead of UV light for curing, exploiting the two-photon absorption cross section of the resin, objects with high spatial resolution can be fabricated, even beyond the diffraction limit. My thesis describes the design, fabrication and testing of a range of optically driven micromachines, microprobes and microtools, including micromotors smaller than 10 microns across fabricated by this method. There is an ongoing effort in our group in characterizing optical micromachines theoretically, through computational modelling, and experimentally. More specific, n-fold rotational symmetry micro-objects are being investigated in terms of torque exerted on them by laser beams. My thesis provides an experimental insight into the angular momentum (both orbital and spin) exchange between the laser light and the micro-objects, with quantitative measurements for the exerted torques. I also investigate the possible use of the microfabricated objects for biological applications, in particular integration of micromachines with biological molecules (DNA, molecular motors). I will begin by explaining the principles of optical tweezers, the optical drive used for the produced micromachines in this thesis. Next I introduce the notion of “micromachine” and the available driving methods as well as symmetry considerations for optimal optical drive. I will then describe the photopolymerization process and our method of producing microstructures. The spatial resolution achieved by the two-photon photopolymerization process is discussed and I will show that we can achieve lateral resolution in the order of 150 nm. In the last part of my thesis I describe the types of micromachines elements I fabricated with examples illustrating transfer of spin and orbital angular momentum by measuring the spin and orbital torque exerted on the microfabricated particles.
Keyword micromachines
two-photon photopolymerization
optical tweezers
optical angular momentum
Additional Notes 32, 57, 78, 86-88, 95, 96, 100, 102, 115, 118, 120, 122-124, 129, 132-134, 136, 137

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Created: Thu, 30 Sep 2010, 13:16:09 EST by Mr Theodor Asavei on behalf of Library - Information Access Service