Real‑Time Observation of Wet Tissues with a DET Membrane (Microscopy, 2022)

A scanning electron microscope (SEM) offers ~0.5 nm spatial resolution and a depth of field roughly 60 times that of a light microscope, yet its high‑vacuum environment has long made it almost impossible to capture wet biological tissues or solution samples in motion. In this study we fabricated an ultra‑thin polyimide film that is both Deformable & Electron‑Transmissive (DET membrane) and established a live‑imaging protocol in which specimens are hermetically sealed by the film and introduced directly into the SEM column. Because the DET membrane conforms to three‑dimensional topography while withstanding the vacuum–atmosphere pressure gap, even large, hydrated samples—such as an excised mouse heart—can be imaged as‑is.

When an excised heart was observed under physiological saline, we simultaneously detected a slow contraction–relaxation oscillation of ~0.58 µm and a superimposed nano‑oscillation of 34 nm amplitude in the orthogonal direction, visualizing for the first time with SEM the multi‑axial beating that occurs under a 3‑D mechanical balance. By adjusting the membrane’s clamping force we could switch between emphasizing fine structure and tracking free motion, allowing quantitative measurement of velocity, period, and directional vectors. The method also enabled real‑time imaging of crystals precipitating, falling, and colliding in solution, as well as tracking ensembles of 1 µm beads—opening a new realm of “wet‑state electron microscopy” for both biological and chemical systems.

Compared with NanoSuit® and SiN windows, the DET membrane uniquely permits high‑resolution video analysis of nano‑dynamics in hydrated organs, cells, and materials, promising broad impact on cardiac mechanics, crystal growth studies, and soft‑matter science.

Article information & citation

Shintani S.A., Yamaguchi S., Takadama H. Real‑time scanning electron microscopy of unfixed tissue in the solution using a deformable and electron‑transmissive film. Microscopy, 71 (5): 297‑301 (2022). 

https://doi.org/10.1093/jmicro/dfac030

Press release

Japanese Physiological Society — Science Topics