Light-driven micro-robotics for contemporary biophotonics.

In the early days of biology, dissection has been the staple for studying the functions of the body and its component organs. The invention of the microscope has paved the way the study of cells, bacteria and other microorganisms. The ability to move such microorganisms or send stimulus in a controlled manner can push our understanding of the dynamics at cellular level. In this regard, the discovery of light’s radiation forces becomes important in the field of biology. The field of optical manipulation has evolved from the simple demonstration of radiation forces to more sophisticated trapping setup and trapped objects. This progress has been augmented with improvements in beam shaping techniques, instrumentation and design of trappable objects. The contribution of this thesis in the optical manipulation literature is to introduce a new set of custom-made trappable objects which we call light-driven micro-robots or light robotics. These are self-contained micro-robots that are designed to perform specific tasks. The first micro-robot that we will present is called the wave-guided optical waveguides (WOWs). The WOWs designed for targeted light delivery where a waveguide structure is fabricated and handles for trapping are attached. The waveguide is coupled with a holography-controlled beam. We have shown three-dimensional movement, tracking and coupling. The second micro-robot is designed for material transport where we have fabricated a vessel that can be trapped and manipulated. In addition, an optically controlled loading and unloading mechanism is built inside the micro-robot. It utilizes photothermal heating to generate convection currents that can draw in and out the cargo. Our results show that we can load and unload cargo which can be an important feature in drug delivery. This thesis is a documentation on the design and fabrication process, sample preparation, experimental procedure and demonstration of the capabilities of the micro-robots and our outlook on their potential use in biophotonics. As we have used tools as extension of our hands in the early study of biology, we envision these micro-robots to be an extension of optical manipulation for studying further down in the micro-scale