title: Optical force sensor array in a microfluidic device based on holographic optical tweezers.
abstract: Holographic optical tweezers (HOT) are a versatile technology, with which complex arrays and movements of optical traps can be realized to manipulate multiple microparticles in parallel and to measure the forces affecting them in the piconewton range. We report on the combination of HOT with a fluorescence microscope and a stop-flow, multi-channel microfluidic device. The integration of a high-speed camera into the setup allows for the calibration of all the traps simultaneously both using Boltzmann statistics or the power spectrum density of the particle diffusion within the optical traps. This setup permits complete spatial, chemical and visual control of the microenvironment applicable to probing chemo-mechanical properties of cellular or subcellular structures. As an example we constructed a biomimetic, quasi-two-dimensional actin network on an array of trapped polystyrene microspheres inside the microfluidic chamber. During crosslinking of the actin filaments by Mg(2+) ions, we observe the build up of mechanical tension throughout the actin network. Thus, we demonstrate how our integrated HOT-microfluidics platform can be used as a reconfigurable force sensor array with piconewton resolution to investigate chemo-mechanical processes.
authors.affiliation: Max-Planck-Institute for Metals Research, Department of New Materials and Biosystems, Heisenbergstr. 3, D-70569 Stuttgart, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Uhrig
authors.forename: Rainer
authors.initials: R
authors.lastname: Kurre
authors.forename: Christian
authors.initials: C
authors.lastname: Schmitz
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Curtis
authors.forename: Tamás
authors.initials: T
authors.lastname: Haraszti
authors.forename: Anabel E-M
authors.initials: AE
authors.lastname: Clemen
authors.forename: Joachim P
authors.initials: JP
authors.lastname: Spatz
mesh_terms: D000199:Actins / Q000737:chemistry / Q000502:physiology; D000465:Algorithms; D040761:Biomimetic Materials; D002138:Calibration; D006696:Holography / Q000295:instrumentation*; D008274:Magnesium / Q000737:chemistry; D044085:Microfluidics / Q000295:instrumentation*; D008856:Microscopy, Fluorescence; D053758:Nanoparticles; D036103:Nanotechnology; D052898:Optical Tweezers; D013499:Surface Properties
chemical_list: D000199:Actins; D008274:Magnesium