Structure-mediated nanoscopy

The science fiction inspired shrinking of macro-scale robotic manipulation and handling down to the micro- and nano-scale regime open new doors for exploiting the forces and torques of light for micro- and nanobiologic probing, actuation and control [1]. Advancing light-driven micro-robotics requires the optimization of optical forces and torques that, in turn, requires optimization of the underlying light-matter interaction. The requirement of having tightly focused beams in optical tweezing systems exemplifies the need for optimal light-shaping in optical trapping, manipulation and sorting [2]. On the other hand, the recent report on stable optical lift shows that optical manipulation can be achieved, even when using unshaped light, by using an appropriately shaped structure instead [3]. Therefore, a generic approach for optimizing light-matter interaction would involve the combination of optimal light-sculpting techniques [4] with the use of optimized shapes in micro-robotics structures [5]. Micro-fabrication processes such as two-photon photo-polymerization offer three-dimensional resolutions for creating custom-designed monolithic microstructures that can be equipped with optical trapping handles for convenient mechanical control using only optical forces [6]. These microstructures can be effectively handled with simultaneous top- and side-view on our BioPhotonics Workstation to carry out proof-of-principle experiments illustrating the six-degree-of-freedom optical actuation of two-photon polymerised microstructures equipped with features easily entering the submicron-regime. Furthermore, we exploited the light shaping capabilities available on the BioPhotonics Workstation to demonstrate a new strategy for controlling microstructures that goes beyond the typical refractive light deflections that are utilized in conventional optical trapping and manipulation. We took this approach to extend the opto-mechanical light-force driven capabilities by including functionalised mechanisms to the fabricated monolithic structures. Aided by collaborators who fabricated test structures with built-in waveguides for us, we were able to put the idea of optically steerable freestanding waveguides – coined: wave-guided optical waveguides - to the test using our BioPhotonics Workstation [7]. We also proposed designing micro-structures for so-called structure-mediated access to the nanoscale and real-time sculpted light for the strongly emerging areas of neurophotonics and optogenetics.