University of Massachusetts Medical School

Cryo EM Magnetic Shielding

New England’s First-of-its-Kind Cryo-Electron Microscopy Facility
Cutting-edge microscope facility opens on UMass Medical’s campus

 

Cryo EM Magnetic shielding was installed in two imaging suites (Titan Krios and Talos Artica ) at UMASS Medical to attenuate AC ELF magnetic field levels. Summary evaluation follows:

At tool column, AC ELF field levels are well within tolerance, indicating the Titan Krios and Talos Artica Imaging suite AC ELF and DC Magnetic field mitigation with magnetic shielding is performing successfully. Along perimeter of the shielded area, magnetic field levels were lower than the resolution of the probe being used to obtain data (0.04 mG) in that area.  As such, the shield is considered to successfully conform to the AC ELF performance specifications.

At each tool column, DC quasi-static levels are consistently greater than specified tool tolerance. DC quasi-static field levels are generated by moving ferromagnetic masses moving through the Earth’s geomagnetic field. Specifically, on this site, levels are generated by workers moving through the hallways outside of the microscopy suites. Analogous field levels will be generated by pedestrians and moving carts through the hallway during the normal course of operation of the TEM instruments.  As such, further mitigation for DC-quasi static fields with an Active Compensation System (ACS) was highly recommended by Vitatech for both electron microscopes.   A combined active vibration isolation platform was integrated into the AC ELF floor shield for each EM tool with a dedicated ACS by TMC as requested by the owner.

The performance requirements for the EMI sensitive instrumentation are specified in the below table.  Magnetic shielding was necessary in the Cryo-EM suites to attenuate AC ELF magnetic field.

EMI Specification Chart for Cryo-Electron Microscopy Suites

Instrument NamePower Frequency
AC ELF 12-60 Hz
Horizontal axis
Power Frequency
AC ELF 12-60 Hz
Vertical axis
DC Quasi-Static
0-12 Hz
FEI Titan Krios30 nT p-p (0.3mG)50 nT p-p (0.5 mG)10 nT p-p (0.1 mG)
FEI Talos Artica80 nT p-p (0.8 mG)100 nT p-p (1.0 mG)30 nT p-p (0.3 mG)

AC ELF and DC quasi-static data was collected at the position of the tool column at elevations of 0.5, 1.0, and 2.0 meters above the floor.  Additional AC ELF data was collected at 1 foot intervals along the perimeter of the entire shielded area.  The greatest peak values along each respective axis are displayed in the below table.  NOTE: The AC ELF and quasi-static DC after shield data shown is before installation of the ACS around the tool columns.   Full tool EMI compliance was achieved after the ACS was installed and operational.

EMI Peak Value Chart for Cryo-Electron Microscopy Suite Post AC ELF Magnetic Shielding

Instrument NamePower Frequency
AC ELF 12-60 Hz
Horizontal axis
Power Frequency
AC ELF 12-60 Hz
Vertical axis
DC Quasi-Static
0-12 Hz
FEI Titan Krios7.1 nT p-p (0.071 mG)6.2 nT p-p (0.062 mG)91 nT p-p (0.91 mG)
FEI Talos Artica19.3 nT p-p (0.193 mG)16.2 nT p-p (0.162 mG)85 nT p-p (0.85 mG)
Posted in: Healthcare Scientific

Project:

Cryo Electron Microscopy Suites

Services Provided:

EMI/RFI Site Testing, Utility & LV Electrical Distribution Simulations & Impact Analysis, EMI/RFI Shielding Designs, Fabrications & Installation & Final Commissioning

Location:

Worcester, MA