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Vacuum Electron Staining Apparatus

Vacuum Electron Staining Apparatus
Overview / Technologies / Products / Technical data / References

Filgen's Vacuum Electron Staining apparatus enables highly efficient, reproducible, and safe electron staining for various electron microscopy(TEM/SEM) specimens.

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What is electron staining?
Electron staining is a method for enhancement image contrast of electron microscopy specimens which are composed with light element (eg. polymer materials, biological specimens etc.), by binding heavy metals. For polymer specimens, osmium tetroxide (OsO4) and ruthenium tetroxide (RuO4) are often used.

What is "vacuum" electron staining?
Conventional electron staining is performed under atmospheric pressure by exposing specimen to gaseous OsO4 or RuO4 or immerses it to those solutions. However, it often causes overstaining or lack of reproducibility. Also, there is a risk for operators to expose to those staining agents which are highly poisonous.
In contrast, our patented technology, vacuum electron staining enables more precise and safer staining by performing staining in vacuum. Staining time and gas pressure (that is, density of staining agent) in reaction chamber as well as timing of gas introducing and exhausting are automatically controlled.

Enhancement image contrast for polymer specimens (TEM)
Fixation for polymer specimens before ultramicrotome sectioning (SEM/TEM)
Reduction of outgassing from specimens at in electron microscope chamber (SEM/TEM)
Elimination or reduction of charging effects on non-conductive specimens (SEM)
Embrittilement of specimens before fracturing (SEM)

Safe operation: no chance to exposure to poisonous agents during staining process
High reproducibility: automated and precise control of staining time and agents density, prevention of overstaining by automated gas exhausting after ataining
Rapid and deeply staining
Effective staining also for hygroscopic specimens: staining is performed by dry gas generated from OsO4 crystal (not aqueous solution)
Less surface contamination: effective for sectionized or otherwise thin sliced specimens
Useful for determining optimal staining condition: staining time is settable by chamber
※Only on 4-chamber models


【Process of Vacuum Electron Staining】

1. Before processing
OsO4 is not introduced to chamber
Chamber is in vacuum
2. Gas introduction
Solenoid A is opened, and C is closed, just after start of the process
Sublimated OsO4 is introduced in chamber gradually
3. Measure of gas density
All solenoids are closed after OsO4 density reaches to set level
4. Staining
Now staining is running in closed chamber
Solenoid C is opened and OsO4 in piping is evacuated
5. Post staining
After the elapse of set staining time, solenoid B is opened and all residual gas is evacuated

【OsO4 reservoir equipped with safety measures】

Our OsO4 reservoir is equipped with some safety measures including a mechanical interlocking system for safety operation.
Gas-tight and robust design
Safety interlocking system with gas port integrated locking pin (see below)
Built-in ampoule cutter: can reduce risks for exposure to toxic OsO4 gas.
Observation window: can check remaining amount of OsO4 crystals
Detachable from main unit and can be stored in freezer
Dimensions: 70(W)×45(D)×120(H) mm

【Overview for the safety interlocking system】

The gas port integrated locking pin of reservoir can simultaneously control status for reservoir locking and gas supply in safe.

Full-openrd (during operation)
Reservoir: locked (undetachable) by manually inserted locking pin of reservoir
OsO4 gas: can be introduced (depends on solenoid status)
Half-closed (before reservoir detach)
Reservoir: locked (undetachable) by manually inserted locking pin of reservoir
OsO4 gas: blocked
※residual gas in the inlet pipe must be evacuated at this step
Full-closed (after operation)
Reservoir: unlocked (detachable)
OsO4 gas: blocked


Interface Interractive touch panel control Mechanical switches, knobs, digital timer/temp controller, and analog vacuum meters
Staining agent OsO4(crystals) in glass ampoule
Density of staining agent 1-10 degree
Staining time 1 min. - 17 hr 0.0 - 999.9 min.
Reaction chamber Number 4 1
Inner size 86(ID) x 50(H) mm
Observation window ✔(upper side)
Heating system ✔(RT - 70 degC)
Reservoir Number 1
Built-in ampoule cutter
Observation window
Storage temp.
*after detaching
-20 ~ 4 degC
Gas introducing/exhausting system Automated control with pirani vacuum gauge, solenoids, and vacuum pump
Safety measure - Fully automated control system with interlocking
- Residual gas trap unit
Gas tight reservoir with built-in ampoule cutter
Size 610(W) x 445(D) x 510(H) mm 450(W) x 425(D) x 445(H) mm
Weight Approx.50kg Approx. 30kg
Vacuum pump Type Two-stage oil rotary vacuum pump
Actual pumping speed 200 L @50Hz
Size 170(W) x 515.5(L) x 249.5(H) mm
Weight 31 kg
Accessories - Gas-tight OsO4 reservoir, 1 pc.
- Vacuum pump, 1 unit
- Residual gas trap unit, 1 unit
- Connecting parts
- Cleaning kit
- Instruction manual (English version, printed)
Price Ask for a quote Ask for a quote


Air Isolation Chamber
Enables electron staining under anaerobic condition
Suitable for materials which have high activity or reactivity with oxygen or moisture (eg, Negative electrode materials of Li-ion battery)
2 different sizes are available;
≫mini - 15(ID) x 6(H) mm
≫middle - 47(ID) x 15(H) mm
Compatible with all Filgen's Vacuum Electron Staining apparatus
Air Isolation Chmber, mini (#VS-MNC) Air Isolation Chamber, middle (#VS-MDC)

TEM Grid Holder (#VS-SGH)
Holds up to 8 pcs of TEM grid
Stainless steel made; high chemical resistance
Compatible with all Filgen's Vacuum Electron Staining apparatus; 45(D) mm

Transportation Containar for OsO4 reservoir (#RVT-1)
Enables safer transportation for OsO4 reservoir
Stainless steel made; proof pressure: 0.02 MPa
Could be used also for atorage for OsO4 reservoir
Dimensions: 198(W) x 118(D) x 102(H) mm, weight: 2.2 kg

Technical data

【Technical data #1 - SEM-EDX analysis for osmium-stained samples】

◆Experimental condition
・Material:adhesive tape
・Staining agent:OsO4
・Gas density(degree of vacuum in chamber):200 Pa
 (1) 1hr stained
 (2) 3hr stained

・(1) 1hr
・(2) 3hr

【Technical data #2 - TEM images of cross-sectioned samples】

◆Experimental condition
・Material:adhesive tape
・Staining agent:OsO4
・Gas density(degree of vacuum in chamber):200 Pa
 (1) 1hr stained
 (2) 3hr stained



With Vacuum Electron Staining, deeper staining with shorter staining time is possible.

【Technical data #3 - SEM images of rubber-dispersed polymer with different blend ratio】

◆Experimental condition
・Material:rubber-dispersed polymer with different blend ratio
・Staining agent:OsO4
・Gas density(degree of vacuum in chamber):1000 Pa
・Staining time:999.9 min.
 (1) Rubber polymer ratio 8:2
 (2) Rubber polymer ratio 6:4
 (3) Rubber polymer ratio 4:6
 (4) Rubber polymer ratio 2:8


【Technical data #4 - Reconstructed 3D images by electron tomography】

◆Experimental condition
・Material:triblock copolymer film
・Staining agent:RuO4
 *Note: ruthenium staining feature is aveilable only in japan.
 (1) Vacuum electron staining
 (2) Conventional electron staining


Uniform staining is observed from vacuum electron stained specimen.


Rina Maeda, Takeshi Higuchi, Kenta Okuhara, Ryohei Kikuchi, Atsushi Takahara, Christopher K Ober, Hiroshi Jinnai, and Teruaki Hayakawa, Interface manipulated two-phase nanostructure in a triblock terpolymer with a short middle segment, Polymer Journal(2016)48, 533-538

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