High-Throughput Imaging of Cells Using Microlenses

A novel microfluidic system uses microlenses for simultaneous imaging of cells in multiple channels

Gregor Holzner and coworkers from the deMello group have devised a novel method for imaging flowing cells in a microfluidic chip using a microlens array. The combination of microlenses, aligned with multiple parallel channels, and a low-magnifying objective enabled simultaneous high-resolution imaging of cells flowing in separate channels. The system successfully achieved a throughput of 50,000 cells per second and can help significantly in the advancement of flow cytometry, a technique used for analysing the physical and chemical characteristics of cells in flow.

Microfluidic systems often require high-magnification objectives to resolve sub-cellular features. These high magnification objectives have a smaller field of view, imaging only a small area of the microfluidic channel. Although low-magnification objectives have a larger field of view, they cannot resolve sub-cellular features. In this case, microlenses—micron-sized low-magnification lenses—can provide additional magnification for resolving sub-cellular features. This use of advanced optical elements with microfluidics falls under the scope of optofluidics, a field of growing importance for the extraction of more information from a microfluidic experiment.

The research lead by Dr. Stavros Stavrakis, developed a novel optofluidic system that uses microlenses for high-throughput and high-resolution imaging of flowing cells. These microlenses were fabricated on a thin coverslip using thermal reflow—a technique for heat activated reshaping of polymers. The microlenses were carefully aligned with each microchannel to generate small areas of higher magnification. Subsequently, numerous such areas were imaged simultaneously under a low magnification objective. Furthermore, the number of cells flowing through the field of view was maximized by ordering the cells towards the middle of the channel using fluid forces. The system successfully discriminated between two cell lines with varying sizes at an exceedingly high throughput of 50,000 cells per second. This technology can pave new avenues for cell classification and rare cell detection for disease diagnostics.

Written by Ankit Jain

Read the full paper here.