Automated Sample Delivery in Serial Femtosecond Crystallography (SFX)
Serial femtosecond crystallography (SFX) uses X-ray pulses from free-electron laser (FEL) sources. SFX may open the way to determine the structure of biological molecules that fail to crystallize readily into large well-diffracting crystals. Taking advantage of FELs with high pulse repetition rates could lead to short measurement times of just minutes. Automated delivery of sample suspensions for SFX experiments could potentially give rise to a much higher rate of obtaining complete measurements than at today’s third generation synchrotron radiation facilities, as no crystal alignment or complex robotic motions are required. New challenges arise from the resulting high rate of data collection, and in providing reliable sample delivery.
To deliver the samples, a emulsion jet is dispensed in a vacuum chamber via a nozzle that is oriented and positioned by a SmarAct SMARGON goniometer. The goniometer consists of four linear stages that are attached to a larger rotation stage, forming a partially parallel kinematic structure. Each of the stages is equipped with SmarAct’s piezo drive technology that provides nanometer-resolved and repeatable movements.
The 5D goniometer system allows tilting the liquid jet by ± 30° and moving it by ± 15 mm. A special feature is a magnetic exchange system that allows picking a nozzle from a nozzle magazine.
SmarAct’s 5D goniometer is part of this automated sample delivery system that leads to shorter measurement times and therefore higher sample throughput.
 Possibilities for serial femtosecond crystallography sample delivery at future light sources, L. M. G. Chavas, L. Gumprecht and H. N. Chapman, Structural Dynamics 2, 041709 (2015), doi: 10.1063/1.4921220