Technological development of a micro-array of individually addressable ejectors

The conception and fabrication of an ejection micro-systems, devoted to local deposition of chemical or biological reagents for low cost and highly flexible biochips or lab on chip fabrication is described. The ejection micro-systems is an array of individually addressable bubble jet ejectors. These ejection micro-arrays have been fabricated using monolithical silicon technologies. Individual ejectors are 140 μm apart corresponding to 4096 ejectors/cm2 and are supported by a dielectric and stress-free SiO2/SiNx membrane, avoiding thermal interactions between neighbours. Ejection nozzles have been realized using SU8 photoresist in order to increase the jet directionality. Ejection has been demonstrated for water, ethanol and acetonitrile for power consumption ranging from 41 mW to 1.1 W and for electrical pulse ranging from 50 μs to 50 ms. Depending on the operating conditions the ejected droplets can have nanolitres to picolitres volume.