A micromachined clog-free ejector for long-term reliable hydrogel printing

Abstract

This paper presents a novel technique for long-term reliable hydrogel printing by employing a thin liquid-film based microfluidic valve mechanism. Common and major clogging problems of microfluidic ejectors by various bio-fluids such as hydrogels and oligonucleotides are very well known. By employing electrowetting technique to drive a thin liquid film of oil, which is immiscible to the hydrogels to be printed, an effective microfluidic valve mechanism has been implemented. Based on the new microfluidic valve technique, we have successfully demonstrated very reliable printing of hydrogels (carrying media of tissue cells) without any clogging problem. While the nozzle was clogged completely in an hour under ambient condition without any protection from the microfluidic valve, it shows clean and fresh printing even after 72 hours of standby time due to the discontinued evaporation by closing of the thin liquid-film based microfluidic valve.