Super-resolution imaging based on cleanable, controllable, and convenient microdroplet generation

Like traditional solid microspheres, liquid microdroplets can focus light for microscopic imaging. Zhai et al. developed a method that creates microdroplets consistently and controllably using optical tweezers. This enables a larger field of view and higher imaging quality in life science and precision measurements.

This work is the first application of the photogenerated droplet phenomenon in microscopic imaging. The team found that compared to solid microspheres, the droplets are highly controllable in size and growth rate and can be easily cleaned via rinsing without physically damaging the sample.

“The liquid droplets generated under the optical tweezers system have the same high refractive index and high surface curvature as solid microspheres, so they can replace the microspheres in imaging applications,” author Cong Zhai said. “The droplet can be directly generated according to the observation requirements, without the scattering process on the sample surface like solid microspheres. In addition, with easy flexibility and affinity with the sample, the droplet can better fill the gaps of the sample and achieve higher-quality illumination and imaging effects.”

To generate the droplets stably and consistently, the team used microfluidic technology consisting of a laser, an injector, and an air pump. Adjusting the laser power and running time enabled the team to generate droplets of the required size and attach them to a target position on the sample for observation.

Zhai said the group will explore the influence of other parameters such as viscosity and concentration in future studies.

Source: “An optical tweezer-based microdroplet imaging technology,” by Cong Zhai, Yujian Hong, Zuzeng Lin, Yulu Chen, Han Wang, Tong Guo, Chunguang Hu, Nanotechnology and Precision Engineering (2023). The article can be accessed at https://doi.org/10.1063/10.0019602 .