Biological Applications of Helium Ion Microscopy

The helium ion microscope (HIM) has recently emerged as a novel tool for imaging and analysis. Based on a bright ion source and small probe, the HIM offers advantages over the conventional field emission scanning electron microscope. The key features of the HIM include (1) high resolution (ca. 0.25 nm), (2) great surface sensitivity, (3) great contrast, (4) large depth-of-field, (5) efficient charge control, (6) reduced specimen damage, and (7) nanomachining capability. Due to the charge neutralization by flood electron beam, there is no need for conductive metal coating for the observation of insulating biological specimens by HIM. There is growing evidence that the HIM has substantial potential for high-resolution imaging of uncoated insulating biological specimens at the nanoscale.