Conventional photocatalytic micromotors are limited to the use of specific wavelengths of light due to their narrow light absorption spectrum, which limits their effectiveness for applications in biomedicine and environmental remediation. We present a multiwavelength light-responsive Janus micromotor consisting of a black TiO microsphere asymmetrically coated with a thin Au layer. The black TiO microspheres exhibit absorption ranges between 300 and 800 nm. The Janus micromotors are propelled by light, both in HO solutions and in pure HO over a broad range of wavelengths including UV, blue, cyan, green, and red light. An analysis of the particles' motion shows that the motor speed decreases with increasing wavelength, which has not been previously realized. A significant increase in motor speed is observed when exploiting the entire visible light spectrum (>400 nm), suggesting a potential use of solar energy, which contains a great portion of visible light. Finally, stop-go motion is also demonstrated by controlling the visible light illumination, a necessary feature for the steerability of micro- and nanomachines.

The advanced state of diabetic retinopathy, a leading cause of blindness, is treated by panretinal photocoagulation (PRP), a repetitive procedure performed by a surgeon using a handheld laser probe. In its place we propose a soft-robotic flexible probe precisely steered using magnetic fields generated by an external magnetic steering system. We develop a kinematic model for the PRP task and show that the process can be automated given image feedback of the retina through a fundus camera. We demonstrate the concept in an eye phantom of a human eye, achieving clinical-level accuracy and faster speeds than human surgeons.

Retinal disorders, including age-related macular degeneration, are leading causes of vision loss worldwide. New treatments, such as gene therapies and stem cell regeneration, require therapeutics to be introduced to the subretinal space due to poor diffusion to the active component of the retina. Subretinal injections are a difficult and risky surgical procedure and have been suggested as a candidate for robot-assisted surgery. We propose a different actuation paradigm to existing robotic approaches using remote magnetic navigation to control a flexible microcannula. A flexible cannula allows for high dexterity and considerable safety advantages over rigid tools, while maintaining the benefits of micrometer precision, hand tremor removal, and telemanipulation. The position of the cannula is tracked in realtime using near-infrared tip illumination, allowing for semiautomatic placement of the cannula and an intuitive user interface. Using this tool, we successfully performed several subretinal injections in ex-vivo porcine eyes under both microscope and optical coherence tomography visualization.

We introduce the modelling and control of a rolling microrobot. The microrobot is capable of manipulating micro-objects through the use of a magnetic visual control system. This system consists of a rod-shaped microrobot, a magnetic actuation system and a visual control system. Motion of the rolling microrobot on a supporting surface is induced by a rotating magnetic field. As the robot is submerged in a liquid this motion creates a rising flow in front, a sinking flow behind, and a vortex above the robot, thus enabling non-contact transportation of micro-objects. Besides this fluidvortex approach, the microrobot is also able to manipulate micro-objects via a pushing strategy. We present the design and modelling of the 50×60×300 µm micro-agent, the visual control system, and an experimental analysis of the micromanipulation and control methods.