3D printed nozzles on a silicon fluidic chip

Serial femtosecond crystallography is a new method for protein structure determination utilizing intense and destructive X-ray pulses generatedby free-electron lasers. The approach requires the means to deliver hydrated protein crystals to a focused X-ray beam and replenish themat the repetition rate of the pulses. A liquid-jet sample delivery system where a gas dynamic virtual nozzle is printed directly on a silicon-glassmicrofluidic chip using a 2-photon-polymerization 3D printing process is implemented. This allows for rapid prototyping and high-precisionproduction of nozzles to suit the characteristics of a particular sample and opens up the possibility for high-throughput and versatile sampledelivery systems that can integrate microfluidic components for sample detection, characterisation, or control. With the hybrid systemdescribed here, stable liquid jets with diameters between 1.5 μmat liquid flow rate of 1.5 μl/min and more than 20 μmat liquid flow rate of 100μl/min under atmospheric and vacuum conditions are generated. The combination of 2D lithography with direct 3D printing may streamlinethe integration of free-form-features and also facilitate scale-up production of such integrated microfluidic devices that may be useful in manyother applications such as flow cytometry and optofluidic