Nanoscale observation of materials and biological samples in liquid by scanning electron assisted dielectric microscopy

Abstract The ability to observe biological samples and nanoparticles at nano-level resolution in aqueous solutions without prior treatment is important for the analysis of the functions of the biological samples and nanomaterials. However, direct observation of samples in solution is difficult with conventional optical and electron microscopes due to restrictions such as limited resolution, denaturation due to vacuum, and low contrast. Recently, we have developed a scanning electron assisted dielectric microscope (SE-ADM) that allows observation of biological samples and nanoparticles in solution with high resolution and high contrast by detecting the potential change caused by electron beam irradiation. Using this method, we have succeeded in observing samples such as bacteria, cultured cells and milk. Furthermore, by integrating an X-ray elemental analysis system into the SE-ADM, elemental analysis of nanoparticles in solution is also possible. We believe this system will advance the analysis of nanoparticles and biological samples in many fields.