Optically controlled coalescence and splitting of femtoliter/picoliter droplets for microreactors.

Microreactor technology has attracted tremendous interest due to its features of a large specific surface area, low consumption of reagents and energy, and flexible control of the reaction process. As most of the current microreactors have volumes of microliters or even larger, effective methods to reduce the microreactors' sizes and improve their flexibility and controllability have become highly demanded. Here we propose an optical method of coalescence and splitting of femto-/pico-liter droplets for application in microreactors.

Accumulation, Directional Delivery and Release of Nanoparticles along a Nanofiber.

Controllably accumulating and delivering nanoparticles (NPs) into specific locations are a central theme of nano-engineering and important for targeted therapy or bacteria removal. Here we present a technique allowing bidirectional accumulation, directional delivery and release of nanoparticles through two 980-nm-wavelength counter-propagating evanescent waves in an optical nanofiber (NF). Using 713-nm-diameter polystyrene NPs suspension and an 890-nm-diameter NF as an example, we experimentally and theoretically demonstrate that the NPs delivered along the NF surface in opposite directions are accumulated into the region where the scattering loss of the NPs is maximum, and about 90% of the incident optical field from both ends of the NF can be coupled into the region.

Bio-compatible miniature viscosity sensor based on optical tweezers.

Viscosity is a fundamental biomechanical parameter related to the function and pathological status of cells and tissues. Viscosity sensing is of vital importance in early biomedical diagnosis and health monitoring. To date, there have been few methods of miniature viscosity sensing with high safety, flexible controllability, and excellent biocompatibility.

Metal-Nanostructure-Decorated Spider Silk for Highly Sensitive Refractive Index Sensing.

Highly sensitive detection of refractive index (RI) is essential for the analysis of the bio-microenvironment and basic cellular reactions. To achieve this, optic-fiber RI sensors based on localized surface plasmon resonance (LSPR) have been widely used for their flexibility and high sensitivity. However, the current optic-fiber RI sensors are mainly fabricated using glass, which makes them face the challenges in biocompatibility and biosafety.