Innovation and Partnerships Office

Matched Illumination and Detector Interferometry Scanning Transmission Electron Microscopy (MIDI-STEM) for Efficient Phase-Contrast Imaging 2015-170



  • Analyzing material interfaces
  • Imaging classes of materials that are challenging to image conventionally


  • High signal efficiency
  • Good transfer of low spatial frequency information
  • Enables imaging while in-focus to minimize signal delocalization
  • Anticipated to enable complete aberration correction
  • Adaptable to all TEM instruments with pixelated detectors


Berkeley Lab researcher Colin Ophus has developed Matched Illumination and Detector Interferometry-Scanning Transmission Electron Microscopy (MIDI-STEM), a technology for visualizing soft matter, and the interface between hard and soft matter, in-focus, at atomic or near-atomic resolution to enable efficient phase-contrast imaging in STEM. The technology addresses the challenge of imaging the following classes of materials, which are difficult to image conventionally:

  • Hard-soft interfaces
  • Low-atomic number nanoparticles
  • Biomolecules such as 1D and 2D protein structures
  • Zeolites and metal-organic frameworks (MOFs)
  • 2D materials such as graphene, MoS2, and BN that scatter weakly

As indicated in Figure 1, a multislice simulation of a DNA snippet connecting two gold nanoparticles – an archetypal hard-soft interface – illustrates the advantages of MIDI-STEM imaging relative to Bright Field (BF)- and Annular Dark Field (ADF)-STEM. MIDI-STEM uses far less electron dose than BF-STEM and ADF-STEM so it can be used on dose-sensitive soft matter, and is adaptable to all TEM instruments with pixelated detector.

Regular electron microscopy methods used by biologists require thousands of identical particles isolated from each other; therefore, many soft matter samples cannot be used. Cryo-electron-microscopy offers in-focus imaging only if the sample is isolated far enough away from other structures so defocused signals do not overlap. 3D reconstruction using Cryo-EM requires thousands of images. In addition, many samples including hard-soft interfaces such as functionalized nanoparticles, cannot be imaged with Cryo-EM.


Figure 1: MIDI-STEM imaging relative to Bright Field (BF)- and Annular Dark Field (ADF)-STEM.

DEVELOPMENT STAGE: Proven principle

STATUS: Patent pending. Available for licensing or collaborative research.

Ophus, C., Ciston, J., Pierce, J., Harvey, T. R., Chess, J., McMorran, B. j., Czarnik, C., Rose, H. H., Ercius, P. “Efficient Linear Phase Contrast in Scanning Transmission Electron Microscopy with Matched Illumination and Detector Interferometry.” Publication in press (2015).