Polymeric fully inertial lab-on-a-chip with enhanced-throughput sorting capabilities

In biology and medicine, the application of microfluidics filtration technologies to the separation of rare particles requires processing large amounts of liquid in a short time to achieve an effective separation yield. In this direction, the parallelization of the sorting process is desirable, but not so easy to implement in a lab on a chip (LoC) device, especially if it is fully inertial. In this work, we report on femtosecond laser microfabrication (FLM) of a poly(methyl methacrylate) (PMMA) inertial microfluidic sorter, separating particles based on their size and providing an enhanced-throughput capability. The LoC device consists of a microchannel with expansion chambers provided with siphoning outlets, for a continuous sorting process. Different from soft lithography, which is the most used technique for LoC prototyping, FLM allows developing 3D microfluidic networks connecting both sides of the chip. Exploiting this capability, we are able to parallelize the circuit while keeping a single output for the sorted particles and one for the remaining sample, thus increasing the number of processed particles per unit time without compromising the simplicity of the chip connections. We investigated several device layouts (at different flow rates) to define a configuration that maximizes the selectivity and the throughput.