Automatic loop centring with a high-precision goniometer head at the SLS macromolecular crystallography beamlines.

Area of Science:

• Crystallography
• Structural Biology
• Automation in Scientific Instrumentation

Background:

• Automated sample handling is crucial for high-throughput crystallographic data collection.
• Accurate centering of crystal loops is a key step in preparing samples for X-ray diffraction.
• Existing manual methods can be time-consuming and prone to user error.

Purpose of the Study:

• To develop and implement an automated loop centering system for crystallographic data collection.
• To improve the speed and accuracy of sample centering compared to manual methods.
• To integrate robotic sample mounting capabilities.

Main Methods:

• Algorithm development utilizing boundary and center-of-mass detection across two microscope magnifications.
• Implementation of a novel flexural-hinge-based compact goniometer head for precise sample alignment.
• Integration of an electromagnet for robotic wet sample mounting.

Main Results:

• Automated loop centering achieved in 15-26 seconds, comparable to manual speed.
• High precision alignment with a circle of confusion smaller than 1 µm (r.m.s.).
• Bidirectional backlash of the goniometer head measured below 2 µm.

Conclusions:

• The developed automatic loop centering system significantly enhances the automation of crystallographic data collection.
• The system offers high speed, accuracy, and integrates advanced robotic sample handling.
• This advancement is expected to improve efficiency and data quality in structural biology research.