Digital twin of a droplet microarray platform: Evaporation behavior for multiple droplets on patterned chips for cell culture

Precise control of the evaporation of multiple droplets on patterned surfaces is crucial in many technological applications, such as anti-icing, coating, and high-throughput assays. Yet, the complex evaporation process of multiple droplets on well-defined patterned surfaces is still poorly understood. Herein, we develop a digital twin system for real-time monitoring of key processes on a droplet microarray (DMA), which is essential for parallelization and automation of the operations for cell culture. Specifically, we investigate the evaporation of multiple nanoliter droplets under different conditions via experiments and numerical simulations. We demonstrate that the evaporation rate is not only affected by the environmental humidity and temperature but is also strongly linked to the droplet distribution on the patterned surfaces, being significantly reduced when the droplets are densely distributed. Furthermore, we propose a theoretical method to aid in the experimental detection of volumes and pH variation of evaporating droplets on patterned substrates. This versatile and practical strategy allows us to achieve active maneuvering of the collective evaporation of droplets on a DMA, which provides essential implications for a wide range of applications including cell culture, heat management, microreactors, biochips, and so on.