Microfluidic system with integrated microinjector for automated Drosophila embryo injection

Abstract

Drosophila is one of the most important model organisms in biology. Knowledge derived from the recently sequenced 12 genomes of various Drosophila species can today be combined with the results of more than 100 years of research to systematically investigate Drosophila biology at the molecular level. In order to enable automated, high-throughput manipulation of Drosophila embryos, we have developed a microfluidic system based on a Pyrex-silicon-Pyrex sandwich structure with integrated, surface-micromachined silicon nitride injector for automated injection of reagents. Our system automatically retrieves embryos from an external reservoir, separates potentially clustered embryos through a sheath flow mechanisms, passively aligns an embryo with the integrated injector through geometric constraints, and pushes the embryo onto the injector through flow drag forces. Automated detection of an embryo at injection position through an external camera triggers injection of reagents and subsequent ejection of the embryo to an external reservoir. Our technology can support automated screens based on Drosophila embryos as well as creation of transgenic Drosophila lines. Apart from Drosophila embryos, the layout of our system can be easily modified to accommodate injection of oocytes, embryos, larvae, or adults of other species and fills an important technological gap with regard to automated manipulation of multicellular organisms.