Preparativa EM Ted Pella
The PELCO easiSlicer™ introduces the new standard in vibratory slicing. It combines ease of operation, precise engineering and affordable pricing in a high quality instrument. The PELCO easiSlicer™ uses rigid construction and advanced engineering technologies to essentially eliminate backlash resulting in minimal Z-axis vibration normally associated with more expensive vibratory slicers. All operational controls are located on the front of the instrument, clearly labeled and sealed against moisture. The specimen tray is held securely in the polypropylene bath by a set of strong magnets.
The amplitude and speed controls are conveniently mounted in the center of the control panel for ease of operation. The sturdy, removable blade holder is offered in 3 angles: fifteen, eighteen and twenty-one degrees to provide choice for each individual application. This eliminates the need to calibrate the blade angle. The specialized design of the blade holder provides a secure and rigid grasp of the cutting blade. This stability of design removes the weakening or bending of parts as seen in a spring clamp design. Feather® Blades are recommended but the blade holder will accommodate other types of blades. The Sectioning Window Controls guide the user for precise cutting window control with indicator lights on the control panel to maintain consistency of placement.
The Magnifier and Light Assembly offers bright white LED lighting (no risk of high temperatures) with high or low settings, depending on the user’s need. The Magnifier can be moved out of the viewing path, if desired. The entire assembly operates smoothly on metal slides.
The large Section Thickness Knob is centrally located in the work area. The knob is labeled in microns and has a perceptible detent every 5 microns. One complete revolution of the knob is 100 microns. The entire bath and tray assembly is raised and lowered by this Section Thickness Knob. The PELCO easiSlicer™ has a Return Switch that provides the user with an option for Auto Return after each slice. In the Manual Return mode, the cutting will cease once the end of the section window has been reached. This allows the retraction of the specimen before the return of the blade in order to prevent damage to the specimen.
The PELCO easiSlicer™ comes equipped with tools and supplies to start cutting quality, consistent sections, right out of the box.
The MicroSlicers™ allow to cut sections of soft tissues like brain, liver or similar difficult-to-section material. The MicroSlicers™ are well known for their quality and superior performance, enjoying an excellent reputation in the neuroscience research community.
The MicroSlicers™ have a unique design for the vibratory motion of the cutting blade. To generate the shuttling blade motion in the MicroSlicer™, a smooth motorized system was adopted that is less prone to vertical vibration, compared to the traditional electromagnetic vibrating system. Traditional electromagnetic system is limited to a set constant vibration frequency of the blade. In contrast, the MicroSlicer™ allows adjustment to the shuttling frequency of the blade depending on the properties of the specimen. Thus, the MicroSlicer™ can cut thinner sections more easily and efficiently.
Objective of the MicroSlicer™
The MicroSlicer™ is an instrument designed to cut sections of animal or plant tissues, fresh or fixed, without freezing them.
Various fields of neuroscience, histochemistry and cytochemistry require incubation of tissues in different incubation media. Large tissue blocks and thick sections often end up with non-specific deposits of reaction products and areas of no reaction in the center of the specimen. This is due to poor penetration of the reaction media into the tissue. For this reason, thinner sections are preferred to perform histochemical and cytochemical reactions.
The simplest method to cut tissue sections is to cut frozen in a cryostat. However, it is well known that both cellular fine structure and enzyme activity suffer greatly from freezing and thawing. Nonfrozen sections are therefore preferred for histochemistry and cytochemistry. In recent years, rat or cat fresh brain sections (200 to 500 micrometers in thickness) have been used in neurophysiological and pharmacological research. In addition, tissue sections are used in a variety of studies in the field of botany.
Traditionally, non-frozen tissue sections have been cut by hand with a razor blade or by using microtomes or tissue choppers. However, these methods have various drawbacks, such as the irregular thickness of tissue sections, difficulty of obtaining thin sections, or extremely slow sectioning speed. The MicroSlicers™ are instruments for preparing non-frozen tissue sections easily and efficiently.
There is a choice of two MicroSlicer™ models:
MicroSlicer™ DTK-1000N – the basic model for manual operation
MicroSlicer™ Zero 1N – reduced Z-axis movement of the head for superior cutting quality, manual operation but includes motorized specimen movement and features the useful retraction mode
The MicroSlicer™ vibratory tissue slicer systems feature a fixed cutting amplitude and an adjustable frequency. Even the entry level model, DTK-1000N, comes equipped with an auto-reverse mechanism and detachable bath. In addition to that, the Zero 1N has a stepping motor for vertical movement of the specimen, as well as a retraction function. The Zero 1N model features the MicroSlicer™ Zero-Z technology with a redesigned cutting head for dramatically reduced Z-axis vibration. The layout of the switches on both sides of the tray allows for easy operation and reduced spillage on the controls.
This device is designed to cut fresh or fixed tissue for metabolic experiments. It is especially advantageous for slicing small or irregular shaped specimens as one might obtain from biopsies. The McIlwain Tissue Chopper causes much less disturbance of the cell structure than homogenizers or blenders and has been used on various tissues of the central nervous system as well as for liver and kidney.
Slices up to 1mm thickness and cubes or prisms up to 1mm cross section can be prepared with the chopper in 30 seconds. Stepless variation of slice thickness from zero to the maximum is done by means of an indexing clutch in conjunction with a micrometer head calibrated in microns. The specimen is placed on the circular, white plastic disc on the stainless steel table and is transversed automatically from left to right at an adjustable speed.
The McIlwain Tissue Chopper is also available with a petri dish cutting table. Please note that the blade holder and cutting table are modified to accommodate Ø60 x 13.7mm H petri dishes. These specialty, sterile, Polystyrene Petri Dishes (see below) are required for use with the petri dish table. The standard McIlwain Tissue Chopper can also be converted for petri dishes by replacing the standard blade holder and cutting table with the respective parts below.
For one of the most common glow discharge applications, making TEM support films or grids hydrophilic using air, the PELCO easiGlow™ uses an automated and quick cycle with fully selectable parameters. The microprocessor controlled system also offers full manual control for all parameters and an advanced protocol programming feature for custom designed glow discharge applications. Parameters and protocols can be stored to facilitate consistent glow discharge results. Open the shipping box, plug it in, and you can start.
The PELCO easiGlow™ Glow Discharge Cleaning System is a compact, quick and easy to use standalone system. It is primarily designed for cleaning TEM grids and hydrophilization of TEM carbon support films, which have the tendency to be hydrophobic. A glow discharge treatment with air will make a carbon film surface negatively charged (hydrophilic) which allows aqueous solutions to spread easily. Manufactured in USA.
With increasingly demanding imaging applications, using clean and consistent quality TEM grids and supports has become more important than ever. Glow discharge treatment of TEM grids removes adsorbed hydro carbons, cleaning them while making them hydrophilic. The PELCO easiGlow™ is an affordable and easy to operate glow discharge system for any TEM lab.
The practical chamber size with its newly designed glow discharge head and adjustable stage with glass slide holder allows for easy loading and fast turnaround times. The system is fully microprocessor controlled and includes an intelligent touch screen device for control and display of operation parameters. The PELCO easiGlow™ supports both hydrophilic and hydrophobic treatment with either negative or positive charge and includes two separately controlled gas inlets. The required vacuum level is set by an electronically controlled precision proportional valve. This novel approach eliminates manual setting with a needle valve. A gentle venting procedure ensures that the TEM grids are not disturbed when the system is vented.
The PELCO® Tripod Polisher™ 590 was designed by researchers at the IBM East Fishkill Laboratory* to accurately prepare TEM and SEM samples of pre-specified, micron-sized regions. For TEM samples, this technique has been used successfully to limit ion milling times to less than 15 minutes and, in some cases, has eliminated the need for ion milling. Although this technique was designed for preparing semiconductor cross-sections, it has been used to prepare both plan-view and cross-section samples from such diverse materials as ceramics, composites, metals, and geological samples.
Features & Benefits
Precise cross-sectioning at the TEM level
Repeatable and rapid production of TEM samples
Reduces ion milling time to minutes as opposed to hours
Produces large thin areas over the entire specimen
Operation – Standard Technique
The PELCO® Tripod Polisher™ 590 can be used to prepare a sample for both SEM and TEM cross-sectional analysis. To accomplish this, the sample is mounted on the face of a special SEM stud which is clamped into the slotted L-bracket of the PELCO® Tripod Polisher™ 590. Initial grinding is done on a 15μm metal bonded diamond disc. Further lapping and polishing continues with a succession of diamond films ranging in size from 30μm to 0.5μm. The final polish is done with a colloidal silica suspension. As lapping progresses, the two rear micrometers are used to adjust the plane of polish. With periodic examinations in an inverted microscope, the plane of polish is adjusted until it is parallel to the plane of interest. At this point the SEM stud may be moved to an ion mill for a quick milling to remove fine scratches, polishing debris and to give the surface topography prior to SEM analysis. The SEM stud can be mounted directly in the SEM for analysis. When analysis is complete, a TEM sample of the same area is made. The sample is removed from the SEM stud and attached to a single aperture TEM grid. The slotted L-bracket is removed and the TEM grid is attached to the round sample mount which is affixed to the center of the polisher. The sample is now mechanically thinned using Diamond Lapping Film. During this process the sample is periodically examined in an inverted microscope and the micrometers are adjusted to maintain the correct plane of polish. The sample is FINAL polished to 1μm or less and then ion milled for up to 15 minutes.
Operation – Wedge Technique
The preferential thinning and surface topography that occurs in briefly ion milled samples makes the study of interfaces between dissimilar materials difficult. These problems can be reduced by completely eliminating the ion milling step and mechanically polishing the sample to electron transparency by employing the wedge technique. With this technique the SEM stud is replaced, in the slotted L-bracket, with a Pyrex® insert. The sample is mounted on the face of this insert. After the plane of interest is obtained, the sample is removed and mounted on the bottom of the Pyrex® insert. The two rear micrometers are adjusted and the micrometer nearest the sample is retracted to produce a wedge shape as material is removed from the sample. The sample, with the features of interest at the apex of the wedge, is thinned from the back side until the edge of interest is ~1μm thick. The sample is then polished on a final polishing cloth such as our MultiTex Cloth (product number 816-12) with a colloidal silica suspension until thickness fringes are visible (below a few thousand angstroms). The sample is then removed from the Pyrex® insert and attached to a single aperture TEM grid for analysis.
The PELCO® Dimpler™ is the latest model in the evolution of the Dimpler line formerly available from South Bay Technology and provides Automated Precision Thinning of Specimens for TEM Analysis. It is a precision electro-mechanical metallographic lapping instrument that will continuously monitor and control dimpling parameters and accurately terminate at a preset specimen thickness. This breakthrough in electronic and mechanical integration has added repeatability and reliability to the dimpling process, as well as automation.
Several operating functions of the PELCO® Dimpler™ are built in to facilitate repeatable, usable dimpled samples:
The Z position display indicates the termination set point and the dimple depth from the Non-Contact Sensor is analog to digital. The digital LED display in microns is updated once every tool revolution by the Tool Phase Detector at the same angular site. This negates any error due to tool run out, especially significant when using padded tools.
Four factors improve the termination accuracy:
Non-Contact Position Sensor
Tool Phase Sensor
No external measuring device
Magnetically coupled arm damping
The Non-Contact Position Sensor measures the location of the fulcrum arm which corresponds precisely to the thickness of the specimen. This sensor has an accuracy of better than one micron. Since it is non-contacting there are no detrimental effects on the action of the fulcrum arm. The reaction time of the sensor is fast enough to terminate the dimpling process the first time the Tool Phase Sensor indicates that the Z termination set point has been reached. Specimen thickness is measured directly on the PELCO® Dimpler™ with the tool surface as the measuring point. The dimple depth and the Z termination set point are measured with the same reference. This prevents any measurement error from being translated directly to a termination error.
Damping of the arm is accomplished by using position information from the Non-Contact Position Sensor, processing it and feeding it back to the arm motor, which controls the up/down force of the arm. The position sensor and the processing circuit is fast enough to actively dampen any vibration the arm may experience. Since the damping force is magnetically coupled to the arm there is no mechanical play in the system, allowing damping response on the sub-micrometer level. Damping is adjustable from zero damping to stiff damping.
Damping offers three significant attributes:
Vibrations that can crack thin specimens are greatly reduced.
Keeps tools round, negating excess impacts, providing more accurate Z position control.
Tool gently contacts the specimen when the arm is lowered.
Automated features make the dimpling process more repeatable and easy to use. Tools are raised and lowered at the touch of a button; dimpling force, damping force, fine balance, and Z offset (termination point) all are set from the front panel.
Once dimpling has begun no monitoring is necessary. After the initial specimen thickness has been measured, the specimen is mounted and the user simply selects a dimple depth and begins dimpling. The precise Z position of the tool/surface interface is continuously displayed while dimpling with any tool. When the selected dimple depth is reached the PELCO® Dimpler™ controls will automatically raise the arm then stop the tool rotation, specimen rotation, and clock timer.
Specimens are mounted on optically smooth sapphire flats. Low thermal mass of the flat reduces mounting and dismounting times and the smooth surface allows the dimpled specimens to be gently slipped off. The hardness of sapphire limits damage if specimens are accidentally dimpled through due to operator error. The retainer ring which secures the sapphire flat also serves as a slurry reservoir. A specimen mounting jig is used for specimen centering during mounting. For off center dimples a special Eccentric Platen with a centering microscope is available.
Tools 1i and 2i are flatting tools and Tools 3i and 4i are dimpling tools. Tools 2i and 4i are supplied pre-padded with various types of metallographic polishing pad. In addition to saving the user the time of padding tools the machine formed padded tools have TIR (Total Indicator Reading) approaching Tools 1i and 3i Dimpling tool geometries have been improved, so that Dimpling Tools 3i and 4i will produce 380 micron diameter dimpled areas.
Research has indicated that Tools 2i and 4i have a working diameter within the nap of the pad. Whereas the ΔZ (change in Z offset value) between the specimen and the hard tool surface is virtually zero, the ΔZ between the “working interface” and the specimen is a function of dimpling force, tool speed, damping force, and pad compliance. After the dimpling force, tool speed, and damping force are selected, the working diameter will stabilize at the working interface of the pad. This working interface is monitored on the Z display and used as a reference location from which a specimen is to be dimpled further. A user can control the dimple depth and removal with a virtually seamless padded tool. This position control allows the dimpling force to approach zero within 1 gram increments.