Factory-on-chip: Modularised microfluidic reactors for continuous mass production of functional materials

Droplet microfluidics provide an advanced platform for functional material synthesis. However, the process has been largely limited to the scale of laboratory study with the device known as lab-on-chip. Here, a multi-dimensional scale-up strategy based on modularised microfluidic reactors is presented to develop large-scale devices defined as factory-on-chip, achieving throughput enhancement to the industrial production scale. Under the guidance of the derived principle, an up-scaling system is demonstrated with eight microchannels parallelized to form an array, ten arrays stacked as the module, and five modules integrated in a system with 400 channels in total. Experiments showed that the circular array arrangement improved the uniformity of product droplets by 42.4% compared to that achieved with a parallel array. The stacking effect was also investigated with two types of material production systems. Chitosan/TiO2 composite microspheres, as advanced wastewater treatment material, were continuously synthesized in mass production with a narrow size distribution of 3.59%, which could hardly be achieved with conventional methods. The material exhibited a methyl-orange dye removal efficiency of 65.3%, which constitutes an improvement of 10.8% compared to single-component chitosan microspheres.