Generalized phase contrast-enhanced diffractive coupling to light-driven microtools

Abstract

Abstract. We have previously demonstrated on-demand dynamic coupling to optically manipulated microtools coined as wave-guided optical waveguides using diffractive techniques on a "point and shoot" approach. These microtools are extended microstructures fabricated using two-photon photopolymerization and function as freefloating optically trapped waveguides. Dynamic coupling of focused light via these structures being moved in three-dimensional space is done holographically. However, calculating the necessary holograms is not straightforward when using counter-propagating trapping geometry. The generation of the coupling spots is done in real time following the position of each microtool with the aid of an object tracking routine. This approach allows continuous coupling of light through the microtools which can be useful in a variety of biophotonics applications. To complement the targeted-light delivery capability of the microtools, the applied spatial light modulator has been illuminated with a properly matched input beam cross section based on the generalized phase contrast method. Our results show a significant gain in the output at the tip of each microtool as measured from the fluorescence signal of the trapping medium. The ability to switch from on-demand to continuous addressing with efficient illumination leverages our microtools for potential applications in stimulation and near-fieldbased biophotonics on cellular scales. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Rational design of light-controlled microrobots

“…By designing a hollow microrobot that can be heated we introduced a syringe function for suctioning small particles from its immediate proximity and delivering the particles to a different location 21 . We have also reported wave-guided optical waveguides that have potential as single-cell tip-enhanced Raman scattering probes 44,45 . All these applications were made possible by the rational design of the microtools in relation to the target application.…”

Optical catapulting of microspheres in mucus models—toward overcoming the mucus biobarrier

“…Our setup for catapulting microspheres benefits from an extended working distance made possible by using low numerical aperture (NA) objectives. [49][50][51] Using counter-propagating catapulting beams, it has also been demonstrated that such low NA setups can actuate microstructures by transversely translating and adjusting the relative intensities of the beam pairs. [49][50][51] Low NA objectives allow the light to interact with the sample environment in a wider, 3-D manner, which will allow us in the future to perform advanced studies using different microtools.…”

“…[49][50][51] Using counter-propagating catapulting beams, it has also been demonstrated that such low NA setups can actuate microstructures by transversely translating and adjusting the relative intensities of the beam pairs. [49][50][51] Low NA objectives allow the light to interact with the sample environment in a wider, 3-D manner, which will allow us in the future to perform advanced studies using different microtools. 45,48 Furthermore, this extended geometry facilitates the extraction of z-depth information through direct side-view imaging.…”

Light driven micro-robotics with holographic 3D tracking

“…(5)-(10) show an opto-mechanical probe-interaction with a tiny surface-positioned object. Adapted from refs [3,4]…”