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Specimen
Preparation
Equipment

Description:

The specimen preparation equipment in both the Shepherd Labs and Nils Hasselmo facilities allows samples to be prepared for microscopy from a wide variety of materials and biological sources.  Techniques include cutting, polishing, ion-milling, chemical etching, carbon and metal coating, ultra-rapid freezing, freeze-fracture, and cryo-embedding.  A variety of inspection microscopes are also available to monitor and record the progress of the specimen preparation process.

Equipment:

Buehler IsoCut Diamond Saw   (78 Shepherd Labs)
Perimeter outside cutting saw removes slices from bulk material >= 0.5 mm thick.

Application:
  • Preliminary stage in TEM sample preparation particularly useful for ceramics and semiconductors.


Buehler Minimet Polisher/Grinder   (78 Shepherd Labs)
The Minimet polisher/grinder may be used to prepare a wide range of specimen samples through fine grinding, rough polishing, and final polishing.


VCR Corer Model V7100   (78 Shepherd Labs)
This precision coring tool, is an accurate, adjustable-speed, table-top drill press.  It is equipped with a soft metal core drill and a diamond impregnated core drill which will produce 3 mm diameter specimens.


Metallographic Polishing Wheels   (78 Shepherd Labs)
The 8" polishing wheels can be used with tripod polishers for grinding and polishing operations to produce scratch-free planar surfaces or electron-transparent "wedge" specimens (tripod polishing).

Applications:
  • Produce electron transparent specimens.
  • Planarization of SEM/AFM specimens.
  • Allows sectioning of specific areas of samples, e.g. specific devices on an IC.


VCR Dimpler   (78 Shepherd Labs)
Dimpling produces an ultra-thin region necessary for successful, artifact-free ion thinning yet maintains a robust peripheral thickness that helps prevent breakage while handling the specimen.  Prethinning with the dimpler also reduces specimen preparation time in an ion mill from 20-25 hours to as little as five minutes.

Application:
    Many materials can be dimpled: gallium arsenide, germanium, sapphire, oxides, carbides, borides, silicides, glasses, multi-phase materials, III-V semiconductors, aluminum alloys, ceramics, carbon composites, and others.


Gatan Precision Ion Polishing System (PIPS)   (78 Shepherd Labs)
The PIPS is a precision polisher which works by ion milling at a very low, but variable, angle.  Low sputtering angles have the advantage of minimizing radiation damage and beam heating while at the same time producing specimens having exceptionally large, clean electron transparent areas, and a minimum of differential milling-rate artifacts.

Applications:
  • Final step in TEM prep for many materials, including ceramics, semiconductors, and metals
  • Thins to electron transparency


Tenupol-3 Electro-Polisher   (78 Shepherd Labs)
The Tenupol-3 is an automatic instrument for electrolytic thinning of specimens for TEM examination where the thickness of the specimens must correspond to or be smaller than the grain size of the examined material.

Application:
  • Thins to electron transparency


Leica EM UC6 Ultramicrotome
Specialist: Fang Zhou   (1-234 Nils Hasselmo Hall)
Leica Ultramicrotome UC6 The Leica EM UC6 Ultramicrotome offers a range of outstanding features and benefits of use from the absolute beginner to the skilled ultramicrotomist.  The eucentric movement of the viewing system allows examination of sections even with lowered water level (as with e.g. Lowycryl) without loss of ergonomic posture.  Defined positions provide optimal positioning of the stereo microscope for alignment with glass and diamond knives.  The innovative touch sensitive control unit of the Leica EM UC6 enables fast and safe alignment of knife and specimen with help files and prompts to hand for beginners.  The AutoTrim function with programmable knife and cutting movements simplifies the trimming process.

Leica Ultramicrotome UC6 Leica Ultramicrotome UC6 closeup

Visit the Leica website for more information ...


Reichert UltraCut S Ultramicrotomes With Model FC-S Cryo Attachments
Specialist: Fang Zhou   (1-234 Nils Hasselmo Hall)
The Reichert UltraCut S is a state-of-the-art ultramicrotome system featuring user-friendly controls, precise knife and sample movements, excellent and highly versatile lighting, and a variety of sample holder options for semi-thin and ultra-thin sectioning of resin-embedded samples.

The Model FC S is a cryo-ultramicrotome system specifically designed for routine ultrathin frozen sectioning when coupled to the UltraCut S ultramicrotome.  A cryo-chamber surrounding the sectioning area is cooled continuously by liquid nitrogen pumped from a Dewar flask.  The automatic pumping system ensures a stable low temperature environment around the frozen specimen.  The temperature of the knife, specimen, and cryo-chamber atmosphere can be individually controlled and then continuously regulated by the cryo control unit, which also regulates the liquid nitrogen pumping system.  At any time during sectioning, the operator can monitor these temperatures on the display.

The Reichert UltraCut S in the Shepherd Labs Facility is normally configured for cryo-ultramicrotomy (coupled to FC S unit) while the UltraCut S in the NHH Facility is normally configured for room temperature sectioning.  Its FC S unit can be added as needed.

Applications:
  • Polymer sections for TEM
  • Biological specimens
  • Materials science specimens

Ultramicrotomy Services

Ultrathin sectioning (using diamond knife) and subsequent staining of embedded biological specimens, and preparing formvar support films, is available on a fee for service basis.  Diamond knives and other specialized tools and equipment ARE NOT provided by the NHH facility for use by others.


Tousimis Model 780A Critical-Point Dryer   (NHH Facility)
Tousimis Model 780A photo The Tousimis Critical Point Drying System is used to complete the dehydration of biological specimens and other materials from their native hydrated states prior to observation in the SEM.  Water is removed from the samples by passing them through a series of increasingly concentrated ethanol solutions, and the pure ethanol-saturated samples are then transferred to the system's high-pressure chamber where the ethanol is replaced by liquid carbon dioxide.  The chamber temperature is then raised to bring the carbon dioxide saturated samples to the CO2 critical point; that being the combination of temperature and pressure where the phase boundary between the liquid and gas phases disappears and the two phases coexist.  The chamber pressure is then vented very slowly, allowing the CO2 to leave the sample in the gas phase, but without surface tension effects that would otherwise cause damage to sample ultrastructure.  This semi-automated system is reliable and easy to operate.

Application:
  • Biological specimens (bulk tissues, cell cultures, single cells)

Operating Instructions  [  PDF 89kB]


LKB Knifemaker Model 7801 B   (Shepherd Labs and NHH Facility)
The LKB Knifemaker enables the efficient production of economical glass knives for ultramicrotomy, from glass strips of either 25 or 38 mm width.


Balzers MED 010 Turbo Mini Deposition System   (NHH Facility)
The MED 010 mini deposition system is a compact turbo-pumped vacuum deposition system.  It accepts the Gatan Model 626-DH Cryotransfer System cold stages for magnetron sputter coating of SEM samples with Pt, Cr, or W at ambient to ultra-low temperatures.  As currently configured, it also serves to evacuate the Gatan cold stage dewars during regeneration of their molecular sieves.


Denton DV-502A High Vacuum Deposition System   (NHH Facility)
Denton DV-502A High Vacuum photo The DV-502A system consists of a conventional diffusion pump and oil-filled rotary pump vacuum system with a 12" bell jar chamber and a variety of electrode assemblies and feedthroughs to permit:

  • Conventional "cool" magnetron-type sputter coating for SEM using gold-palladium or pure gold targets.  Under standard conditions (15 millitorr argon) the coating rate is approximately 10 nm / 30 seconds.
  • Thermal evaporation of carbon to provide conductivity and beam damage protection for thin sectioned materials to be observed in the TEM., and to produce pure carbon support membranes for "whole-mount" TEM samples prior to negative staining.
  • High-temperature "bakeout" of thin molybdenum apertures from SEMs and TEMs to remove hydrocarbon contaminants.
  • "Glow-discharge" treatment of formvar, parlodion, or similar thin film plastic specimen supports to reduce hydrophobicity and enable surface wetting in negative stain and similar sample preparations.


VCR High Resolution Indirect Ion-Beam Sputtering System   (NHH Facility)
VCR High Resolution Indirect Ion-Beam Sputtering System photo The VCR sputtering system deposits extremely thin (~1-2 nm) and fine-grained ~1-4 nm) coatings of platinum, tungsten, carbon, etc. coatings to samples for SEM observation.  The target material is bombarded by a beam of ionized argon gas accelerated to approximately 9 kV.  The ejected target material then impacts the sample surface which is rotated through a variety of angles during the coating process.  The coating accumulates at approximately 0.1 to 0.2 nm per minute and can be carefully controlled and easily reproduced.

Operating Instructions  [  PDF 660kB]


Balzers HPM 010 High Pressure Freezer   (NHH Facility)
HPM 010 High Pressure Freezer photo The HPM 010 High Pressure Freezer allows specimens up to 0.6 mm thick, with a total volume of ~ 1 mm3, to be vitrified (producing microcrystalline or amorphous ice) at the relatively slow rate of freezing, compared to plunge or slam methods, of 200°C / second. Samples are vitrified in ~ 30-50 milliseconds by exposing them to jets of liquid nitrogen at 2100 Bar for ~ 500 milliseconds.  The method is based on an entirely physical phenomenon that lowers the freezing point of water.  Cells and tissues may be frozen without requiring the addition of chemical cryoprotectants which can introduce artifacts.  Physical immobilization of all cell components by ultrarapid freezing may be vastly superior to conventional chemical fixation at room temperature because diffusion of various chemical fixatives through cells and tissues may take minutes to hours, and not all cell components will react with fixatives at equal rates, or to equal degrees.  Thus cell components may be lost or rearranged.  The method may be used to prepare samples for cryoSEM, for subsequent preparation of freeze-fracture replicas for TEM, and for freeze-substitution, in which fixatives in organic solvents are introduced into the cryoimmobilized samples while still at low temperature, combining chemical fixation and removal of water while preventing collapse and shrinkage of cell ultrastructure.  The high pressure freezing method has also been successfully applied to non-biological materials such as latex emulsions and inks for cryoSEM examination.

The instrument is relatively easy to use, reliable, and robust.  A variety of specimen carriers are available to permit freezing of specimens ranging from ~ 50 to 600 microns in thickness.


Balzers FSU 010 Freeze Substitution Unit   (NHH Facility)
The FSU 010 Freeze Substitution Unit automates the process of dehydration, chemical fixation, and even resin infiltration and polymerization of cryoimmobilized samples at low temperatures.  Timers control the duration of the various process steps, while temperatures are monitored and controlled, from 0?C to -99C, by adjustment of LN2 supply and heaters.  Processes can be programmed to run for several days, with individual steps adjustable in units of hours, minutes, or seconds.

The unit is equipped with a number of specimen holder racks and supports, and a short-wave ultraviolet lamp unit is available for polymerization of low-temperature resins if a complete low-temperature sample preparation process is required.


Bal-Tec BAF 060 Freeze-Fracture System   (NHH Facility)
BAF 060 Freeze-Fracture System photo The BAF 060 Freeze-Fracture System can be used to produce high resolution metal replicas of cryoimmobilized emulsions, liquids, gels, cell suspensions, and tissues, for either TEM or cryoSEM applications.  Samples may be fractured by using double replication specimen tables or cyro-microtomes.  Partial freeze drying or complete freeze drying can also be carried out, and the samples then coated with metal (platinum/carbon; tantalum/tungsten/carbon; platinum/iridium /carbon).  Metal evaporation / coating can be done at angles from 0 to 90.  "DARS" (Double Axis Rotary Shadowing) is also possible.  The evaporation processes are controlled by a quartz crystal thin film monitor.  The two stage vacuum system consisting of a turbomolecular pump combined with a membrane pump assures oil-free vacuum load-lock and sample chamber environments.  All specimen tables, both electron beam guns, and the knife can be exchanged through one rough vacuum load lock to maintain high vacuum in the main chamber.  The vacuum system's control system is designed to prevent the operator from making errors during transfer and processing, and the quick-lock manipulator with integrated movement guide allows error-free and quick specimen transfer.


Pelco CPD2 Critical Point Dryer
Wet specimens are processed through critical point drying with minimal artifacts caused by surface tension effects.

Application:
  • Prepares biological specimens and other wet materials for electron microscopy.