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Tousimis Critical Point Dryers Overview


Tousimis is a well respected manufacturer if critical point dryers (CPD). They have been at the forefront of developing Critical Point Dryers for over 50 years and were one of the first companies to offer CPD systems. The core business of Tousimis still is development and manufacturing of CPD systems. During the more than 40 years of CPD development and manufacturing at Tousimis, many unique innovations have flown into the renowned Tousimis SAMDRI CPD systems. Tousimis currently offers a choice of 7 CPD systems for microscopy and structural applications to cover a wide range of samples.

Tousimis AutoSAMDRI-931, standard chamber, automatic critical point dryer 230V / 50Hz EM-Tec TC1 TEM calibration standard oriented gold crystal Tousimis AutoSAMDRI-931, large chamber, automatic critical point dryer 230V / 50Hz

AutoSAMDRI-931.GL CPD standard
Ø32x32mm chamber.
Touch screen operation
create/store recipes

AutoSAMDRI-931.GL CPD medium
Ø64x32mm chamber.
Touch screen operation
create/store recipes.

AutoSAMDRI-931.GL CPD with large
Ø86x32mm chamber.
Touch screen operating
create/store recipes.

 

Tousimis SAMDRI-815, Series A fully automatic critical point dryer 230V / 50Hz

 

Tousimis SAMDRI-815B, Series A fully automatic critical point dryer with extra large chamber, 230V / 50Hz
EM-Tec TS3 TEM combined test specimen standard

AutoSAMDRI-815 Series A,
fully automatic CPD with standard Ø32mmx32mm chamber

 

AutoSAMDRI-815B Series A,
fully automatic CPD with extra large Ø114mmx32mm chamber

SAMDRI-795 semi-automatic CPD with Ø32mmx32mm chamber

Tousimis SAMDRI-PVT-3D advanced manual critical point dryer 230V / 50Hz

 

Tousimis SOTER condenser to capture waste alcohol
EM-Tec TC3 TEM EDX calibration standard thin Cu foil on Al grid

SAMDRI-PVT-3D manual CPD with Ø32mmx32mm chamber

SOTER condenser to capture waste alcohol

CPD accessories,
sample holders and inserts



Principles of critical point drying (CPD)

              
              Carbon_dioxide_pressure-temperature_phase_diagram

 

Critical point drying is a process to remove liquids in such a way that the internal external structure is not damaged during the drying process. Applications for critical point drying are preparation of biological samples for scanning electron microscopy (SEM), production of aerogel, decaffeination of coffee and production of micromechanical systems. The Tousimis critical point dryers offered on this page are designed for EM sample preparation. CPD aims to prepare biological structures in their original (living) state.

When biological samples are air dried, the liquid changes to gas (evaporate) at a certain rate, while at the same time the amount of liquid is reduced at the same rate. When this happens in a sample, surface tension in the liquid body pulls against any structures the liquid is in contact with. Delicate structures collapse; the sample structure is destroyed and can't be studied. To avoid this, the sample needs to dried above the critical point through the super-critical region.  The super-critical fluid has no distinction between gas and fluid (equal densities) and therefore no liquid to gas boundary phase.

Fluids suitable for critical point drying are:

 Fluid

Critical point temperature

Critical point pressure

 

°C

Bar

PSI

 Acetone

235.0

47.7

681.7

 CO2

31.1

73

1072

 Ethanol

243.1

63.1

915.2

 IPA

235.0

53.0

768.7

 Methanol

240.0

78.7

1141.5

 Water

374.0

217.7

3157.8

 Freon

25.0

37.5

550

       

CO2 is ideal for the CPD process because of the low temperature of the critical point, readily miscible with alcohol, non-flammable, non-toxic, globally abundant with low costs.
In CPD sample preparation, water in the fixated sample has been replaced with alcohol and alcohol is added to the cooled CPD processing chamber. High pressure liquid CO2 (LCO2) is used to replace the alcohol and after this the sample is completely immersed in the super-critical CO2. The LCO2 is then heated until the temperature goes beyond the critical point. After that,  the pressure can be gradually reduced, allowing the gaseous CO2 to escape and leaving an intact dry sample. Before examining the sample in the SEM, it needs to be coated with thin layer of precious metal to make it conductive.
Critical point dried samples shown great actual details and provide ample signal after coating. CPD processing often provides better imaging and allows to store samples for future investigations. These are important advantages compared to imaging with variable pressure with increased water vapour pressure.


 

SEM Supplies

TEM Supplies

Calibration

Sample Preparation

AFM / SPM

  SEM Sample Stubs
  Sample Stub Adapters
  SEM Stage Adapters
  SEM Sample Holders
  Filaments/Cathodes
  Silicon Finder Grid
  Gatan 3View Pins
  FEI Volumescope Pins
  SEM Stub Storage Boxes
  Phenom Supplies
  JEOL NeoScope Supplies
  Hitachi TM series Supplies
  Field & lab sampler kits

Instruments


  Acoustic Enclosures
  Critical Point Dryers
  Cressington SEM Coaters
  HI-Res IR Chamberscope
  TEM Sample Prep
  TEM Grids
  TEM Support Films
  Graphene Films
  Grid Storage Boxes
  Cryo Grid Box
  TEM sample staining
  Filaments/Cathodes
  Cryo Pin for U-M
  Eyelash manipulators

FIB Supplies


  FIB Lift-out grids
  FIB low profile stubs
  FIB grid holders
  FIB pre-tilt holders
  FIB Grid Boxes
  SEM / FIB Magn. Calib.
  SEM Res. Test Spec.
  EDS / WDS Calibration
  TEM Calibration
  AFM / SPM Calibration
  LM Magn. Calibration

Vacuum Supplies


  Bullseye Vacuum Gauges
  D215V Vacuum Controller
  D801W Vacuum Gauges
  Quick-check Gauges
  KF/NW Vacuum Parts
  Vacuum oil and grease
  Vacuum sample storage
  Evaporation baskets
  Quartz QCM Crystals
  Sputter Targets
  Carbon Rods & Fibers
  Quartz QCM Crystals
  Supports & Substrates
  SEM Preparation Stands
  Tweezers
  Probes & Picks
  Lab scissors
  Applicators & Swabs
  Plastic Transfer Pipettes
  Cutting Tools
  Conductive Paint/Cement
  Conductive Tapes &Tabs
  Non-conductive Adhesives
  Stainless Steel Mesh
  Sample Storage
  Tools
  Preparation mats & tiles
  Cleaning
  Diamond Polishing Paste
  AFM/SPM Discs
  AFM/SPM Holders
  AFM/SPM Disc Storage
  Cantilever Tweezers
  AFM/SPM Discs Tweezers
  Mica Discs
  HOPG Substrates


LM


  Correlative Cover Slips
  Glass Microscope Slides
  Glass Cover Slips
  Quartz Microscope Slides
  Quartz Cover Slips
  Black metal slides
  Slide storage boxes
  Calibration
  Plastic Transfer Pipettes

 

 

 

EM-Tec multiple stub holders for Hitachi cylinder SEM stubs EM-Tec Multiple pin stub holders