Yao Zhang

Optofluidic manipulation provides a powerful route for guiding micro- and nanoparticles, yet conventional light-induced flow systems often suffer from limited controllability, unstable flow patterns, and poor reconfigurability. Here, we demonstrate programmable optofluidic steering based on multibeam engineering of Marangoni convection technique (MEMCT) around optothermally generated air bubbles. In our MEMCT, focused laser irradiation on a gold film creates localized photothermal heating near an air bubble, thereby reshaping the temperature distribution along the air–water interface. By varying the position, number, and spatial arrangement of laser-induced heat sources, we generate tunable flow patterns ranging from directional transport to complex vortical circulation. Simulations and experiments confirm that these reconfigurable interfacial stress fields can deterministically steer single or multiple particles along prescribed trajectories. Furthermore, by integrating it with microfluidic cross-junctions and extending this strategy to bubble arrays, we realize pump-free, on-demand particle routing. This programmable Marangoni-flow platform offers a simple and versatile strategy for dynamic particle manipulation, with potential applications in lab-on-a-chip systems, micro/nanorobotics, and biophotonic technologies.

On-chip optical trapping necessitates substrates that generate strong near-field forces while mitigating thermal instability. Here, metallic semi-continuou

Optical manipulation and detection of single molecules, such as biomolecules and bacterial viruses, are crucial in single-molecule mechanics and biosensing

Rapid and accurate detection of microorganisms is critical to clinical diagnosis. As Raman spectroscopy promises label‐free and culture‐free detection of biomedical objects, it holds the potential to rapidly identify microorganisms in a single step. To stabilize the microorganism for spectrum collection and to increase the accuracy of real‐time identification, we propose an optofluidic method for single microorganism detection in microfluidics using optical‐tweezing‐based Raman spectroscopy with artificial neural network. A fiber optical tweezer was incorporated into a microfluidic channel to generate optical forces that trap different species of microorganisms at the tip of the tweezer and their Raman spectra were simultaneously collected. An artificial neural network was designed and employed to classify the Raman spectra of the microorganisms, and the identification accuracy reached 94.93%. This study provides a promising strategy for rapid and accurate diagnosis of microbial infection on a lab‐on‐a‐chip platform.

A Fano resonance originates from the resonant coupling between interacting multipoles inside nanostructures. It breaks the symmetry of spectral line shape and enables Fano‐resonant media to present unusual scattering properties. However, understanding the mechanical effects of such multipolar coupling systems is highly complex compared with the traditional simple dipole. In this work, using single Si nanospheres as the Fano‐resonant media, optical forces arising from different types of Fano resonances including the electric, magnetic, and magnetoelectric Fano resonances are investigated. It is shown that the directions of these types of forces are tunable in three dimensions. The necessary condition to realize a direction change of the Fano‐resonance‐induced forces and elucidate the underlying physics are presented. Furthermore, it is found that the Fano‐resonance‐induced forces exhibit strong polarization‐dependent properties which traditional optical (dipolar) forces cannot possess.

This feature issue of Biomedical Optics Express presents a cross-section of interesting and emerging work of relevance to the use of biological cells or microorganisms in optics and photonics. The technologies demonstrated here aim to address challenges to meeting the optical imaging, sensing, manipulating and therapy needs in a natural or even endogenous manner. This collection of 15 papers includes the novel results on designs of optical systems or photonic devices, image-assisted diagnosis and treatment, and manipulation or sensing methods, with applications for both ex vivo and in vivo use. These works portray the opportunities for exploring the field crossing biology and photonics in which a natural element can be functionalized for biomedical applications.

Optical trapping, transportation, coalescence and splitting of femto-/pico-liter microdroplets are realized based on a scanning optical tweezing system. On this basis, the microdroplets are used as microreactors to conduct the microreactions.