Tractor beam acoustic levitation for time resolved crystallography experiments

Proof of concept of serial crystallography is carried out through the translation of samples delivered by tractor beam levitation. This is achieved using arrays of low powered transducers, focused to produce acoustic traps. Contrary to traditional Langevin Horn levitators, power requirement remains in the region of 10W, limiting the acoustic pressure on the levitated samples and hence the risk of damage to them. Automation is achieved by controlling the phase of the transducers. The traps and associated samples steadily translate with the controlled acoustic field. A translation speed of 2.8mms -1 between the nodal distance of the traps is achieved. This results in sequential delivery of sample containing droplets performed with 1.5s between each delivery. The results demonstrate the ability to capture automated measurements of diffraction from lysozyme micro-crystals. Our study points in the direction of an automated, acoustic levitation system for time-resolved crystallography.