Cross-sectional imaging of C. elegans by SEM-CT using Environmental SEM for nanomanipulation

A novel technique was presented for a cross-sectional imaging of Caenorhabditis elegans (C. elegans) by Scanning Electron Microscope - Computed Tomography (SEM-CT) using Environmental-SEM (E-SEM) for nanomanipulation applications. In our previous works, a nanorobotic manipulation system was established inside the E-SEM for water-contained samples including biological organism with a real-time high resolution observation. However, the SEM image is two dimensional (2D) and surficial information from the secondly electrons. Hence, it is not able to evaluate the targeted structure inside the sample. In this research, we presented the cross-sectional observation of the sample by SEM-CT system which is used the X-ray generated by the electron beam of SEM. To improve the signal-to-noise ratio of CT imaging, we evaluated the following ways, 1) apertures for X-ray before/after irradiating the sample, 2) adjustment of emission currents of the electron beam, 3) iteration processing of captured images. To reduce the damage of C. elegans during observation, a method was used to immerse the C. elegans by a liquid oil. The proposed 3D imaging technique is useful to evaluate the 3D manipulation of the C. elegans, such as nano-injection application with functional micro-nano beads inside the C. elegans.