A pneumatically driven inkjet printing system for highly viscous microdroplet formation

Abstract

This paper introduces a pneumatically driven inkjet printing system that forms highly viscous microdroplets in the nanoliter volume range. The printing system has a unique printing mechanism that uses a flexible membrane and an effective backflow stopper. While typical inkjet systems can handle liquids with a limited range of viscosity due to energy loss by viscous dissipation at the nozzle and ineffective backflow management within their systems, our printing system can print liquids with viscosity as high as 384.5 cP. In the viscosity range 1–384.5 cP, we investigated printing characteristics such as printed droplet volume, standoff distance, and maximum possible frequency. The droplet formation showed outstanding reliability, with the droplet volume exhibiting a coefficient of variation less than 1.07 %. Our printing system can be directly used in inkjet applications with functional liquids over a broad viscosity range.