Non-destructive observation of intact bacteria and viruses in water by the highly sensitive frequency transmission electric-field method based on SEM

Journal Article · Fri Aug 08 04:00:00 EDT 2014 · Biochemical and Biophysical Research Communications

DOI:https://doi.org/10.1016/J.BBRC.2014.07.062· OSTI ID:22416706

Ogura, Toshihiko

Highlights: • We developed a high-sensitive frequency transmission electric-field (FTE) system. • The output signal was highly enhanced by applying voltage to a metal layer on SiN. • The spatial resolution of new FTE method is 41 nm. • New FTE system enables observation of the intact bacteria and virus in water. - Abstract: The high-resolution structural analysis of biological specimens by scanning electron microscopy (SEM) presents several advantages. Until now, wet bacterial specimens have been examined using atmospheric sample holders. However, images of unstained specimens in water using these holders exhibit very poor contrast and heavy radiation damage. Recently, we developed the frequency transmission electric-field (FTE) method, which facilitates the SEM observation of biological specimens in water without radiation damage. However, the signal detection system presents low sensitivity. Therefore, a high EB current is required to generate clear images, and thus reducing spatial resolution and inducing thermal damage to the samples. Here a high-sensitivity detection system is developed for the FTE method, which enhances the output signal amplitude by hundredfold. The detection signal was highly enhanced when voltage was applied to the metal layer on silicon nitride thin film. This enhancement reduced the EB current and improved the spatial resolution as well as the signal-to-noise ratio. The spatial resolution of a high-sensitive FTE system is 41 nm, which is considerably higher than previous FTE system. New FTE system can easily be utilised to examine various unstained biological specimens in water, such as living bacteria and viruses.

• OSTI ID: 22416706
• Journal Information: Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 4 Vol. 450; ISSN 0006-291X; ISSN BBRCA9
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
BACTERIA
ELECTRIC FIELDS
ELECTRIC POTENTIAL
IMAGES
LAYERS
RADIATION EFFECTS
SCANNING ELECTRON MICROSCOPY
SENSITIVITY
SIGNAL-TO-NOISE RATIO
SILICON NITRIDES
SPATIAL RESOLUTION
THIN FILMS
VIRUSES
WATER