Dynamic nano-imaging via a microsphere compound lens integrated microfluidic device with a 10× objective lens.

Optical microscopic imaging techniques are essential in biology and chemistry fields to observe and extract dynamic information of micro/nano-scale samples in microfluidic devices. However, the current microfluidic optical imaging schemes encounter dilemmas in simultaneously possessing high spatial and temporal resolutions. Recently, microsphere nanoscope has emerged as a competitive nano-imaging tool due to its merits like high spatial resolution, real-time imaging abilities, and cost-effectiveness, which make it a potential solution to address the aforementioned challenges. Here, a microsphere compound lens (MCL) integrated microfluidic imaging device is proposed for real-time super-resolution imaging. The MCL consists of two vertically stacked microspheres, which can resolve nano-objects with size beyond the optical diffraction limit and generate an image of the object with a magnification up to 10×. Exploiting the extraordinary nano-imaging and magnification ability of the MCL, optically transparent 100 nm polystyrene particles in flowing fluid can be discerned in real time by the microfluidic device under a 10× objective lens. Contrary to this, the single microsphere and the conventional optical microscope are incompetent in this case regardless of the magnification of objective lenses used, which demonstrates the superiority of the MCL imaging scheme. Besides, applications of the microfluidic device in nanoparticle tracing and live-cell monitoring are also experimentally demonstrated. The MCL integrated microfluidic imaging device can thus be a competent technique for diverse biology and chemistry applications.