A Magnetically Navigated Microcannula for Subretinal Injections.

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 real-time using near-infrared tip illumination, allowing for semi-automatic 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.

Multiwavelength Light-Responsive Au/B-TiO2 Janus Micromotors.

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 TiO2 microsphere asymmetrically coated with a thin Au layer. The black TiO2 microspheres exhibit absorption ranges between 300 and 800 nm. The Janus micromotors are propelled by light, both in H2O2 solutions and in pure H2O 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.