An ejection microarray for in-situ oligonucleotide synthesis on DNA chips

A new microfluidic actuator for in situ oligonucleotides synthesis on DNA chips has been developed. It consists in a microarray of individually addressable ejectors able to deliver pl droplets. The working principle is based on thermal ink-jet printing. The design of the micro injector has been deduced from FEM simulation, in order to achieve 4000 ejectors/cm/sup 2/. The technological fabrication process includes the realisation of a thin dielectric and stress free membrane, of polysilicon heater resistors, and of SU8 photopolymerised nozzles. Ejections have been observed for 50 /spl mu/s pulses and 1.25 W power consumption without satellite droplets.