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Product Information
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April 25, 2013
WPI’s microelectrode holder-half-cells couple fluid-filled glass micropipettes to high input impedance amplifiers. A Ag/AgCl pellet (or a silver wire) molded into the holder body provides stable potential. Electrical connection is made via male 2mm pins or female 2mm sockets. The pipette may be mounted axially or at right angles to the holder. Pipettes are held with screw-caps or rubber gaskets (without caps). Filling WPI microelectrode holders with electrolytes containing chloride results in stable electrode potential. Suitable electrolytes include KCl, NaCl andCaCl2. Holders are supplied for standard WPI single capillary tubing of 1.0, 1.2, 1.5 and 2.0mm outside diameters. (Call WPI regarding custom designs for other glass diameters.) The holder style you select will depend on your experimental application, space, and instrumentation.
Hints for selecting and ordering micropipette holders
- Determine the required electrical connection on the holder. For...more
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April 25, 2013
Choosing the right parts for your application is critical. Below you will find a table comparing many common parts to help you determine just what you need.
Cables
Order code Application/Description Connector A Connector B Cable Length 2851
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April 24, 2013
In this video, WPI Chemist Nikki Scafa demonstrates how to make a 0.1M solution of CuCl2 for calibrating WPI NO microsensors.
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April 24, 2013
In this video, WPI Chemist Nikki Scafa demonstrates how to make a PBS buffer solution for use with WPI microsensors.
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April 24, 2013
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April 24, 2013
Specially designed tips as small as 36 gauge (110 micron OD) are offered in both blunt and beveled styles. Our studies have shown that these tips will cause less trauma to the tissue than any other form of micro syringe currently in use. NanoFil has a unique coupling mechanism that allows many different forms of small tubing and tips to be coupled with the syringe barrel. Direct Microinjection by Hand
This is the simplest and most economical way to inject. Any of our tips can be inserted directly into the NanoFil syringe. Even the SilFlex tubing can be inserted to switch from hand injection to the other methods listed below. The limitation of this method is the difficulty...more
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April 24, 2013
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April 24, 2013
The World Precision Instruments (WPI) EVOM2 is used for making trans epithelial electrical resistance (or TEER) measurements. We recommend that you test your EVOM2 before you use it for the first time and then periodically after that. If there is a concern that the meter or the electrode is not functioning properly, test the meter first. This video shows how to test the meter.
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April 24, 2013
The World Precision Instruments (WPI) EVOM2 is used for making trans epithelial electrical resistance (or TEER) measurements. Two silver/silver chloride pellets are used for the electrodes. The chloride ion tends to migrate, which is a reversible reaction. But, because of this chloride ion swapping, the electrodes need to be polarized before each use. Before using the meter for making voltage measurements, equilibrate the electrodes. This video shows you how.
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April 24, 2013
Contributing Author: Dr. Steve Andre (Muscle Physiologist)
All living cells maintain a difference in electrical charge between the solutions that are inside and outside the cell membranes. The voltage difference across the cell membrane is usually at a steady level known as the resting membrane potential. The resting membrane potentialis produced by the differential distribution of ions on either side of the membrane. In muscle fibers, the potassium concentration inside the cell is over 50 times greater than the ion’s concentration in the extracellular fluid. On the other hand, the concentration of sodium is 10 times greater outside the membrane than inside. The concentration gradient of potassium is greater and in the opposite direction to the sodium concentration gradient. The ion concentrations are governed by three factors:
- Sodium-potassium pump
- Relative rates of diffusion of these ions down concentration gradients
- Attraction...more
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April 24, 2013
A Volt Meter A volt-ohm meter may apply a constant voltage of unknown current across the membrane and damage the cells electrically and also leave a chemical imbalance in the electrodes. WPI experimented with two volt-ohm meters:
- An expensive Fluke meter applies a DC voltage of 50 to 80mV, which (in a 1000Ω membrane) will pass 80µA. With a 200Ω membrane, this is 400µA.
- A discount meter puts out 500mV DC, which will pass 500µA through the membrane. With a 200Ω membrane, this is 2.5mA.
Volt Meter Charges or Electrocutes Cells
When you use a volt ohm meter to test a cell layer, the Ag/AgCl electrodes accumulate an unbalanced chemical charge. If the cells are not electrocuted in the process, they also accumulate a charge. The unbalanced electrodes can now act as a source of voltage and current that has to be overcome to make an accurate measurement.
If a volt ohm meter was employed in a TEER (Trans Epithelial Electric Resistance)...more
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April 24, 2013
Cellular Organization
When building any structure, whether it’s a bridge or a protein, three elements are required:
- Building materials
- Energy
- Building plans
The same is true in biological systems:
- Proteins are the structural material used for building. They provide the shape and substance of cells, tissues, organs and living matter.
- Carbohydrates are converted to energy to fuel the cellular building process. If more energy is available than is required for a project, the carbohydrates are converted to fats for long term energy storage.
- Finally, nucleotides within the nucleus of a cell provide the blueprints for the project.
A Cell – Simplified
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April 21, 2013
The
WPI cannula system for neuroscience study and pre-clinical research includes an entire range of cannula options. You are guaranteed: - Exceptional Quality
- Best Prices
- Rapid Order Response
The three primary components include the Guide Cannula, the Internal Cannula and the Dummy Cannula (cap).
- WPI cannulas are beveled inside and out and then polished to remove any burrs and ensure that the inside diameter is perfectly cylindrical. This limits undesired trauma to tissue and ensures smooth operation.
- WPI offers exceptional quality at the best prices.
- Quantities of each...more
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May 01, 2012
WPI offers both vibration free workstations and platforms, and each is custom-built to meet your specifications. This article describes the options available and how to request a price quote for the unit you need. The vibration-free platform looks like the one shown (left). The workstation tables are similar. These vibration-free units offer vertical and horizontal vibration isolation, high performace active-air suspension and automatic leveling. The diagrams below show dimensions of the workstations.
Understanding Part Numbers ♦ Options Available ♦ Workstation Specifications ♦ Platform Specifications ♦ Performance Data
Understanding WPI Part Numbers
The part numbers define the load, dimensions...more