Development of multi-frequency impedance scanning electron microscopy

Abstract

Nanometre-scale observation of specimens in water is indispensable in many scientific fields like biology, chemistry, material science and nanotechnology. Scanning electron microscopy (SEM) allows high-resolution images of biological samples to be obtained under high vacuum conditions but requires specific sample-preparation protocols. Therefore, there is a need for convenient and minimally invasive methods of observing samples in solution. We have developed a new type of impedance microscopy, namely multi-frequency impedance SEM (IP-SEM), which allows nanoscale imaging of various specimens in water while minimising radiation damage. By varying the frequency of the input voltage signal of the sine wave, the present system can detect dielectric properties of the sample’s composition at nanometre resolution. It also enables examination of unstained biological specimens and material samples in water. Furthermore, it can be used for diverse samples in liquids across a broad range of scientific subjects such as nanoparticles, nanotubes and organic and catalytic materials.

Scanning Electron Microscopy to Study the Nucleation and Growth Phenomena in Liquid Electrolytes under Operando Conditions

“…These 0.5 keV to 8 keV X-rays have a lower ionization cross-section than the 10 keV to 30 keV primary electrons and therefore induce less radiolitic damage to the liquid. Along these lines there is an interesting recent development of impedance LP SEM 32 where electron beam induced tiny modulations of the impedance of the liquid cell are used for object detection. Though the resolution of these microscopies is still lower compared to standard LP SEM, they offer new contrast mechanisms in addition to being less invasive.…”

Structural analysis of melanosomes in living mammalian cells using scanning electron-assisted dielectric microscopy with deep neural network

“…Therefore, the structure of dried and fixed cells may differ from that of living cells. Recently, we are developing a new impedance microscope that is an improved dielectric microscope [36] , [37] . With this method, the impedance information of the sample can be observed by scanning EB while applying an alternating potential signal from below the sample and detecting the impedance signal.…”