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TEM Grids

TEM Support Grids

Transmission Electron Microscopy (TEM) requires samples to be extremely thin (typically <100 nm) so electrons can pass through. Support grids are essential for holding these delicate specimens.

Purpose of TEM Grids
  • Provide a stable platform for ultrathin samples.
  • Allow electron transparency while maintaining mechanical strength.
  • Facilitate sample handling and transfer.
Common Types of TEM Grids
  • Copper grids: Most widely used, good conductivity.
  • Nickel or gold grids: For corrosion resistance or special chemical environments.
  • Carbon-coated grids: Improve sample adhesion and reduce charging.
  • Holey or lacey carbon films: For suspending particles in open areas for imaging.
Applications
  • Biological samples: Thin sections or macromolecules deposited on carbon films.
  • Nanoparticles: Droplets dried on holey grids for imaging in vacuum.
  • Cryo-TEM: Grids with perforated carbon films for vitrified samples.
  • Asbestos Analysis

 

1. Electron Microscopy in Brief
Electron microscopy uses accelerated electrons instead of light, giving much higher resolution (down to sub-angstrom in TEM).

Main EM types:

  • TEM (Transmission Electron Microscopy) electrons transmit through an ultra-thin sample
  • Cryo-EM TEM at cryogenic temperatures (especially for biology)
  • SEM (Scanning Electron Microscopy)   electrons scan the surface
  • STEM hybrid of TEM + SEM principles

The support grids we manufacture are central to TEM and cryo-TEM.

 

2. What Are TEM Support Grids?
A TEM support grid is a thin, perforated metal mesh (typically ~3 mm diameter) that:

  • Holds the specimen
  • Supports fragile, electron-transparent films
  • Allows electrons to pass through the sample into the imaging system

Without grids, most TEM samples could not be mounted or stabilized.

 

3. Materials Used for TEM Grids
The grid material affects conductivity, chemical stability, and beam interaction.

Common grid materials:

  • Copper (Cu)
    - Most common and inexpensive
    - Good conductivity
    - Not suitable for corrosive environments or some biological buffers
  • Gold (Au)
    - Chemically inert
    - Ideal for biological and cryo-EM samples
    - Minimizes charging and contamination
  • Nickel (Ni)
    - Resistant to chemicals
    - Used for analytical TEM (EDS, EELS)
  • Molybdenum (Mo)
    - High temperature stability
    - Used for in situ heating experiments

We also Manufacture grids from Aluminum, Titanium and Stainless Steel

 

4. Grid Mesh Types and Geometry
Grid mesh size determines mechanical support vs viewing area.

  • Mesh numbers (e.g., 200, 300, 400):
    - Higher mesh = smaller holes
    - 300 400 mesh common for biological samples
    - Lower mesh preferred for thicker materials samples
  • Slot grids
    - Large rectangular openings
    - Used for, Long nanowires or Cross-sectional lamellae (FIB-prepared samples)

 

5. Support Films on TEM Grids
Most samples do not sit directly on bare metal grids. Instead, a thin support film spans the holes.

Common support films:

  • Amorphous carbon
    - General purpose
    - Conductive and beam-stable
    - Used in materials science and biology
  • Formvar (polymer) + carbon
    - Flexible and strong
    - Often used for biological sections
  • Hole-y carbon
    - Regular holes in carbon film
    - Crucial for cryo-EM (proteins suspended in vitreous ice)
  • Ultrathin carbon / graphene
    - Extremely low background noise
    - High-resolution imaging of nanoparticles and single atoms

 

6. Applications of TEM Support Grids

A. Biological TEM & Cryo-EM
Purpose: Structural biology, virology, cell ultrastructure

Grid roles:

  • Support ultrathin sections (~50 100 nm)
  • Hold vitrified ice layers in cryo-EM
  • Minimize charging and beam damage

Examples:

  • Protein structure determination (ribosomes, enzymes)
  • Virus morphology (SARS-CoV-2, bacteriophages)
  • Cell organelle imaging (mitochondria, synapses)

Special grids:

  • Gold holey carbon grids for cryo-EM

B. Nanomaterials & Nanotechnology
Purpose: Size, shape, crystallinity, defects

Grid roles:

  • Disperse nanoparticles evenly
  • Reduce background signal
  • Provide conductive support

Examples:

  • Carbon nanotubes on lacey carbon grids
  • Quantum dots on ultrathin carbon
  • Metal nanoparticles for catalytic studies

Graphene grids are increasingly used to:

  • Enhance contrast
  • Reduce beam-induced motion

C. Materials Science & Engineering
Purpose: Microstructure, defects, interfaces

Grid roles:

  • Support FIB-prepared lamellae
  • Enable diffraction and analytical TEM

Examples:

  • Grain boundaries in alloys
  • Dislocations in semiconductors
  • Thin film cross-sections (solar cells, MEMS)

Specialized grids:

  • Mo grids for heating experiments
  • Ni grids for EDS/EELS analysis

D. Analytical TEM (EDS, EELS, Diffraction)
Grid choice is critical because:

  • Grid material can introduce X-ray peaks
  • Thick films can obscure weak signals

Best practices:

  • Use Ni or Mo grids for elemental analysis
  • Use ultrathin carbon films for low background

E. In Situ TEM Experiments
Support grids are used in:

  • Heating holders
  • Electrical biasing chips
  • Liquid cell TEM

Applications:

  • Nanoparticle growth attachment
  • Phase transitions
  • Electrochemical reactions

 

7. Limitations and Challenges of TEM Grids

  • Beam damage to support films
  • Contamination buildup
  • Grid charging (especially with polymers)
  • Sample drift in cryo-EM

Ongoing research focuses on:

  • Graphene-based supports
  • Functionalized grids for selective binding
  • Improved hole geometry for cryo-EM

 

8. Summary
TEM support grids are not passive accessories they critically influence:

  • Image resolution
  • Signal-to-noise ratio
  • Sample stability
  • Analytical accuracy

Their application spans:

  • Structural biology
  • Nanotechnology
  • Semiconductor research
  • Advanced materials engineering