Graphene Liquid Cells Assembled through Loop‐Assisted Transfer Method and Located with Correlated Light‐Electron Microscopy

Abstract

Graphene liquid cells (GLCs) for transmission electron microscopy (TEM) enable high‐resolution, real‐time imaging of dynamic processes in water. Large‐scale implementation, however, is prevented by major difficulties in reproducing GLC fabrication. Here, a high‐yield method is presented to fabricate GLCs under millimeter areas of continuous graphene, facilitating efficient GLC formation on a TEM grid. Additionally, GLCs are located on the grid using correlated light‐electron microscopy (CLEM), which reduces beam damage by limiting electron exposure time. CLEM allows the acquisition of reliable statistics and the investigation of the most common shapes of GLCs. In particular, a novel type of liquid cell is found, formed from only a single graphene sheet, greatly simplifying the fabrication process. The methods presented in this work—particularly the reproducibility and simplicity of fabrication—will enable future application of GLCs for high‐resolution dynamic imaging of biomolecular systems.

Using Single-Crystal Graphene to Form Arrays of Nanocapsules Enabling the Observation of Light Elements in Liquid Cell Transmission Electron Microscopy

“…A graphene window enables one to obtain atomic-resolution images because of its large Young’s modulus (i.e., stiffness in tension) that makes liquid cells thin despite the pressure difference between inside and outside the cells, high electrical conductivity for preventing window charging, and an impermeability to liquid for perfect enclosure. − The first graphene liquid TEM cell configuration had individual liquid pockets with diameters ranging from 100 to 700 nm that were randomly distributed between two graphene sheets transferred to “arrayed lacey TEM grids” (top-left panel in Figure ). − More recently, a more consistent “well-type” graphene liquid cell has been reported in which the liquid is encapsulated between two graphene films transferred to the top and bottom surfaces of a Si 3 N 4– x spacer regularly perforated with nanoholes (bottom-left panel in Figure ). − Although this well-type graphene liquid cell can control the positions and volumes of individual liquid pockets based on the geometry of the nanoholes, the spacer positioned between the two graphene films leads to thick liquid pockets causing a loss of phase contrast and spatial resolution.…”

Using Single-Crystal Graphene to Form Arrays of Nanocapsules Enabling the Observation of Light Elements in Liquid Cell Transmission Electron Microscopy

“…A graphene window enables one to obtain atomic-resolution images because of its large Young’s modulus (i.e., stiffness in tension) that makes liquid cells thin despite the pressure difference between inside and outside the cells, high electrical conductivity for preventing window charging, and an impermeability to liquid for perfect enclosure. − The first graphene liquid TEM cell configuration had individual liquid pockets with diameters ranging from 100 to 700 nm that were randomly distributed between two graphene sheets transferred to “arrayed lacey TEM grids” (top-left panel in Figure ). − More recently, a more consistent “well-type” graphene liquid cell has been reported in which the liquid is encapsulated between two graphene films transferred to the top and bottom surfaces of a Si 3 N 4– x spacer regularly perforated with nanoholes (bottom-left panel in Figure ). − Although this well-type graphene liquid cell can control the positions and volumes of individual liquid pockets based on the geometry of the nanoholes, the spacer positioned between the two graphene films leads to thick liquid pockets causing a loss of phase contrast and spatial resolution.…”

Micrometer-Scale Graphene-Based Liquid Cells of Highly Concentrated Salt Solutions for In Situ Liquid-Cell Transmission Electron Microscopy

“…The significance of the GSLCs in Figure is the encapsulated area (volume) of liquid that covered the microwells on a micrometer scale. In a previous study, the highest population in the size distribution of GLCs was 100–150 nm . Also, round-shaped pocket GLCs with the highest count of 50–100 nm in pocket diameters have been fabricated .…”

“…In a previous study, the highest population in the size distribution of GLCs was 100–150 nm. 41 Also, round-shaped pocket GLCs with the highest count of 50–100 nm in pocket diameters have been fabricated. 42 In such small GLCs, effects of confinement are possible.…”

Radiolysis‐Driven Evolution of Gold Nanostructures – Model Verification by Scale Bridging In Situ Liquid‐Phase Transmission Electron Microscopy and X‐Ray Diffraction

“…Moreover, an overview of reports describing evolution of gold nanostructures from pristine HAuCl 4 solutions in LP‐TEM is provided, showing good agreement with simulated mole fractions. [ 28,32,37–46 ]…”

Using Single-Crystal Graphene to Form Arrays of Nanocapsules Enabling the Observation of Light Elements in Liquid Cell Transmission Electron Microscopy

“…A graphene window enables one to obtain atomic-resolution images because of its large Young’s modulus (i.e., stiffness in tension) that makes liquid cells thin despite the pressure difference between inside and outside the cells, high electrical conductivity for preventing window charging, and an impermeability to liquid for perfect enclosure. − The first graphene liquid TEM cell configuration had individual liquid pockets with diameters ranging from 100 to 700 nm that were randomly distributed between two graphene sheets transferred to “arrayed lacey TEM grids” (top-left panel in Figure ). − More recently, a more consistent “well-type” graphene liquid cell has been reported in which the liquid is encapsulated between two graphene films transferred to the top and bottom surfaces of a Si 3 N 4– x spacer regularly perforated with nanoholes (bottom-left panel in Figure ). − Although this well-type graphene liquid cell can control the positions and volumes of individual liquid pockets based on the geometry of the nanoholes, the spacer positioned between the two graphene films leads to thick liquid pockets causing a loss of phase contrast and spatial resolution.…”

Micrometer-Scale Graphene-Based Liquid Cells of Highly Concentrated Salt Solutions for In Situ Liquid-Cell Transmission Electron Microscopy

“…The significance of the GSLCs in Figure is the encapsulated area (volume) of liquid that covered the microwells on a micrometer scale. In a previous study, the highest population in the size distribution of GLCs was 100–150 nm . Also, round-shaped pocket GLCs with the highest count of 50–100 nm in pocket diameters have been fabricated .…”

“…In a previous study, the highest population in the size distribution of GLCs was 100–150 nm. 41 Also, round-shaped pocket GLCs with the highest count of 50–100 nm in pocket diameters have been fabricated. 42 In such small GLCs, effects of confinement are possible.…”

Radiolysis‐Driven Evolution of Gold Nanostructures – Model Verification by Scale Bridging In Situ Liquid‐Phase Transmission Electron Microscopy and X‐Ray Diffraction

“…Moreover, an overview of reports describing evolution of gold nanostructures from pristine HAuCl 4 solutions in LP‐TEM is provided, showing good agreement with simulated mole fractions. [ 28,32,37–46 ]…”

Using Single-Crystal Graphene to Form Arrays of Nanocapsules Enabling the Observation of Light Elements in Liquid Cell Transmission Electron Microscopy

“…A graphene window enables one to obtain atomic-resolution images because of its large Young’s modulus (i.e., stiffness in tension) that makes liquid cells thin despite the pressure difference between inside and outside the cells, high electrical conductivity for preventing window charging, and an impermeability to liquid for perfect enclosure. − The first graphene liquid TEM cell configuration had individual liquid pockets with diameters ranging from 100 to 700 nm that were randomly distributed between two graphene sheets transferred to “arrayed lacey TEM grids” (top-left panel in Figure ). − More recently, a more consistent “well-type” graphene liquid cell has been reported in which the liquid is encapsulated between two graphene films transferred to the top and bottom surfaces of a Si 3 N 4– x spacer regularly perforated with nanoholes (bottom-left panel in Figure ). − Although this well-type graphene liquid cell can control the positions and volumes of individual liquid pockets based on the geometry of the nanoholes, the spacer positioned between the two graphene films leads to thick liquid pockets causing a loss of phase contrast and spatial resolution.…”

Micrometer-Scale Graphene-Based Liquid Cells of Highly Concentrated Salt Solutions for In Situ Liquid-Cell Transmission Electron Microscopy

“…The significance of the GSLCs in Figure is the encapsulated area (volume) of liquid that covered the microwells on a micrometer scale. In a previous study, the highest population in the size distribution of GLCs was 100–150 nm . Also, round-shaped pocket GLCs with the highest count of 50–100 nm in pocket diameters have been fabricated .…”

“…In a previous study, the highest population in the size distribution of GLCs was 100–150 nm. 41 Also, round-shaped pocket GLCs with the highest count of 50–100 nm in pocket diameters have been fabricated. 42 In such small GLCs, effects of confinement are possible.…”

Radiolysis‐Driven Evolution of Gold Nanostructures – Model Verification by Scale Bridging In Situ Liquid‐Phase Transmission Electron Microscopy and X‐Ray Diffraction

“…Moreover, an overview of reports describing evolution of gold nanostructures from pristine HAuCl 4 solutions in LP‐TEM is provided, showing good agreement with simulated mole fractions. [ 28,32,37–46 ]…”