In situ printing of liquid superlenses for subdiffraction-limited color imaging of nanobiostructures in nature

The nanostructures and patterns that exist in nature have inspired researchers to develop revolutionary components for use in modern technologies and our daily lives.The nanoscale imaging of biological samples with sophisticated analytical tools,such as scanning electron microscopy(SEM)and transmission electron microscopy(TEM),has afforded a precise understanding of structures and has helped reveal the mechanisms contributing to the behaviors of the samples but has done so with the loss of photonic properties.Here,we present a new method for printing biocompatible“superlenses”directly on biological objects to observe subdiffraction-limited features under an optical microscope in color.We demonstrate the nanoscale imaging of butterfly wing scales with a super-resolution and larger field-of-view(FOV)than those of previous dielectric microsphere techniques.Our approach creates a fast and flexible path for the direct color observation of nanoscale biological features in the visible range and enables potential optical measurements at the subdiffraction-limited scale.

Thermometry of photosensitive and optically induced electrokinetics chips

Optically induced electrokinetics(OEK)-based technologies,which integrate the high-resolution dynamic addressability of optical tweezers and the high-throughput capability of electrokinetic forces,have been widely used to manipulate,assemble,and separate biological and non-biological entities in parallel on scales ranging from micrometers to nanometers.However,simultaneously introducing optical and electrical energy into an OEK chip may induce a problematic temperature increase,which poses the potential risk of exceeding physiological conditions and thus inducing variations in cell behavior or activity or even irreversible cell damage during bio-manipulation.Here,we systematically measure the temperature distribution and changes in an OEK chip arising from the projected images and applied alternating current(AC)voltage using an infrared camera.We have found that the average temperature of a projected area is influenced by the light color,total illumination area,ratio of lighted regions to the total controlled areas,and amplitude of the AC voltage.As an example,optically induced thermocapillary flow is triggered by the light image-induced temperature gradient on a photosensitive substrate to realize fluidic hydrogel patterning.Our studies show that the projected light pattern needs to be properly designed to satisfy specific application requirements,especially for applications related to cell manipulation and assembly.