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EVOM2

  1. Researcher Compares EVOM3 with an Ussing Chamber
    April 20, 2021
    by Benjamin Dubansky, PhD, Animal Physiologist/Researcher An Ussing Chamber is used when performing barrier studies across an excised epithelial tissue. Similar measurements can be made in well plates using an EVOM series TEER Measurement Meter, which is used for epithelial tissue that is grown to confluence in a cell culture well. While EVOM measurements are only qualitative, your throughput is much greater with an EVOM3. The EVOMs are portable and much more economical than an Ussing Chamber. Here Ben Dubansky, PhD explains the differences between EVOMs and Ussing chambers. The EVOM is a special kind of voltmeter for measuring electrical properties across a layer of cells in culture or a biological membrane. We are measuring TEER (TER) - Transepithelial Electrical Resistance. The
  2. What I Like About the EVOM Line
    April 20, 2021
    by Benjamin Dubansky, PhD, Animal Physiologist/Researcher The EVOM is a special kind of voltmeter for measuring electrical properties across a layer of cells in culture or a biological membrane. Here's a few things I like about the new EVOM3.   There's a couple things I like about the EVOM3 better than the older models. You can charge it. These ones had batteries which are fine, and they had a power plug. But when you use the power plug, you get a little bit electrical noise, and the signal's not quite as stable. When you have a good battery in here, the charge
  3. Researcher's Review of the EVOM3
    April 19, 2021
    by Benjamin Dubansky, PhD, Animal Physiologist/Researcher The EVOM is a special kind of voltmeter for measuring electrical properties across a layer of cells in culture or a biological membrane. It is the most commonly used commercial system for measuring across a layer of cultured cells. We are measuring TEER (TER) - Transepithelial Electrical Resistance. The EVOM3 allows us to zoom in and measure either resistance or voltage across these membranes or cells in culture.     Why was it invented? The EVOM (Epithelial Volt Ohm Meter) was designed in the 80’s. It was invented b
  4. 7 Reasons to Love the NEW EndOhm Chambers
    May 02, 2019
    EndOhm Chambers Re-engineered EndOhm chambers are designed for making accurate TEER measurement of epithelial and endothelial cell cultures. The design keeps the top and bottom electrodes at a fixed gap and maintains the sample (cell culture insert) in a centered position inside. This design minimizes the variability associated with electrode positioning and gap, making EndOhm chambers more accurate and capable of generating reproducible results. WPI made some recent upgrades to the EndOhm chambers. The NEW EndOhm Chamber is made of GLASS, making it easier to clean and more crack resistant. The chamber can be cleaned with ethanol, isopropanol, bleach, etc. The chambers are still compatible with the original EVOM and EVOM2™ meters. The apical electrode height is adjustable. The chamber comes with a spacer disk. (Video) The crystal clear glass chamber allows better visualization of apical electrode for accurate sample positioning. A new insert holder on the top of the chambers has tri-supports for three leg inserts. This helps keep your cell culture wells in the proper position (centered) when you are making measurements. Three sizes cover a range of well cup sizes from a variety of manufacturers. Make Precise Measurements Using WPI’s EVOM2™ resistance meter/epithelial volt meter, Endohm chambers provide reproducible resistance measurements of endothelial and epithelial monolayers grown in culture cups or inserts. Transfer cups from their culture wells to the Endohm chamber for measurement rather than using hand-held electrodes. The chamber and the cap each contain a pair of concentric electrodes: a voltage-sensing silver/silver chloride pellet in the center plus an annular current electrode. The height of the top electrode can be adjusted to fit cell culture cups from different manufacturers. Endohm’s circular disc electrodes, situated above and beneath the membrane, allow a more uniform current density across the membrane than a system using the STX2 electrodes. Compared with other resistance measurement methods, Endohm with EVOM2™ offers a much more convenient and economic solution to monitor the health of cellular monolayers in terms of TEER values. The EndOhm chamber (combined with the EVOM2™) applies an alternating form of current,  and the chamber design guides the current, creating a more uniform current density across the sample. The EndOhm and EVOM2™ system can produce reliable read outs, because it eliminates most common errors associated with electrode polarization and membrane capacitance. Endohm together with EVOM2™ offers an accurate and economical system to measure resistance of cellular monolayers.  More Info
  5. How To Select Electrodes For Making TEER Measurements
    November 28, 2018
    Selection of Electrodes for TEER Measurements Transepithelial electrical resistance (TEER), also referred as the transepithelial resistance (TER) is used to monitor cellular health. TEER is comprised of measurements of the transcellular pathway (i.e., resistance due to an individual cell) and paracellular pathway (i.e., resistance due to the formation of the cellular junctions). TEER is commonly used to monitor cellular confluence. TEER values can indicate changes in the cellular monolayer permeability, showing the monolayer barrier function of cells such as, endothelial (brain microvessel) and epithelial (alveolar, kidney, and intestinal) cells. High TEER values generally reflect tighter cellular monolayers or cellular junctions (Lewis 1996, Matter and Balda 2003, Denker and Sabath 2011). A few major benefits of WPI TEER measurement systems are described below. The TEER values (electrophysiological analysis) can be combined with other analysis methods to further understand
  6. FAQs about TEER Measurement
    February 02, 2015
    Here are some frequently asked questions (FAQ) about TEER measurement using an EVOM2. Are the electrical resistance and transepithelial electrical resistance (TEER) the same thing? What is an EndOhm chamber? How is an EVOM2 used for measuring confluence? Why use an EndOhm instead of a STX? How do I clean my electrode? What about electrode preconditioning? Can you give me a simple data acquisition system for TEER? What are the TEER measurement challenges that I may encounter? Can you suggest some experimental
  7. Recording TEER Measurements from an EVOM2
    November 11, 2014
    The EVOM2 is the classic, hand-held instrument for making Trans Epithelial Electrical Resistance (TEER) measurements. The REMS system adds a robot and data recording for automated TEER measurements. There may be times when you don't have a robot, but would still like to have the data recording capabilities of the REMS system. With a little ingenuity, you can do just that. Here, we will show you how you can add data recording to your standard EVOM2. Open Labscribe3 on your computer. Let the program identify the data recorder. In our example, we will use a Lab-Trax-4. Choose the default settings. Setup the preferences for one channel. If you like, you may add five points of smoothing.  In the marks section of the main window, select A1 (channel one). This records a data point directly into the marks records window. Alternatively, the smoothed graph C1 may be selected. In the top graph, right click and choose Units>Simple to calibrate the graph to ohms. Enter these values for the EVOM2 conversion: 2 point calibration Apply units to new data Value at Cursor 1: 0.0000 => 0.0000 Value at Cursor 2: 1.0000 => 1000 Unit Name = Ohms To connect the EVOM2 to the data recorder, connect a BNC cable from the Output BNC on the front of the EVOM2 to the Channel 1 input BNC on your data recorder. In the Marks window, enter A1 or Control. Move the electrode to the control well, and allow it to stabilize. Then, press Enter. Otherwise, it is difficult to hold the electrodes still while typing. For each additional well, enter in the number A2…, A3 into the Marks field. Then, move the electrode to that well and press the enter key after the reading stabilizes. Stop the recording and save the file. Open up the marks editor in Labscribe (View>Marks>Marks). The dialog box shows the time mark data and resistance values.   Press the Export button and choose “All Marks.” Give your export file a name. The export files is a text file that may be import into Microsoft Excel or another spreadsheet application.
  8. FAQ: Troubleshooting Unstable Resistance Readings from an ENDOHM
    November 18, 2013
    One of our frequently asked questions (FAQs) concerns TEER measurements with an EndOhm. If the resistance readings from your ENDOHM don't stabilize, you may need to do some troubleshooting. Test the EVOM2 First, test your EVOM2 meter. The 1000Ω test resistor (WPI # 91750) can be used for this purpose.
  9. REMS Auto Sampler - HTS Robot
    October 11, 2013
    The REMS AutoSampler automates measurements of electrical resistance of transepithelial, transendothelial or Caco-2 cell membranes being grown to confluence on microporous filters of high throughput screening (HTS) 24- and 96-well microplates. It is a computer-controlled, tissue resistance measurement system that offers reproducibility, accuracy, flexibility and ease-of-operation for this kind of measurement. Automated measurement of tissue resistance in cell culture microplates provides the important advantages of speed, precision, decreased opportunity for contamination and the instant availability of measured resistance data on a computer. These measurements are useful in applications such as drug bioavailability studies and studies on the mechanisms of drug transport. The main components of the REMS AutoSampler include: Robotic sampler that moves the electrode over each well of the microplate Electrode which is located on the robotic arm Base plate for the 24-and 96-well tray Windows-based data acquisition card REMS interface unit REMS software to operate the system on a Windows-based computer The REMS AutoSampler automates TEER measurements previously made with WPI's EVOM2 Epithelial Voltohmmeter. Automated tissue resistance measurements up to 20kΩ can be performed on 24- or 96-well HTS microplates. Microplates presently supported include the Corning Costar HTS Transwell-24, Falcon HTS Multiwell insert systems, and Millipore Multiscreen™ CaCo 96-well plate. The REMS AutoSampler is designed to facilitate integration with other robotic systems. Special locating bars are installed on the REMS base platform that allow other system robots to place an HTS tray into a precise location on the REMS base. The REMS AutoSampler automatically measures and records tissue resistance from a user-specified matrix of culture wells on the microplate. According to the specified sequence, the robotic arm moves over the identified wells taking TEER measurements. By means of a x-y-z locating system, the electrode-containing arm is positioned precisely and reproducibly over each well. The ability of the REMS AutoSampler to reproducibly and precisely locate the electrode results in highly reproducible TEER measurements. TEER measurements are stored in the computer as the electrode moves from one well to the next. The Windows-based software provides user-friendly features to acquire, display and store the tissue resistance measurements. The REMS electrode is compact and robust in design. Each of two rod-shaped probes, 1.5mm in diameter, consists of a pair of electrodes: one electrode for injecting current and the other for measuring the voltage. The use of two pairs of electrodes eliminates the error caused by the electrode-liquid interface. To take a measurement, the robot inserts one probe into the center of the filter well and the other into the opening slot of the 24- or 96-well plate. The use of AC current to measure resistance provides several advantages over DC current, including: Absence of offset voltages on measurements There is a zero net current being passed through the membrane, and therefore it is not adversely affected by a current charge No electrochemical deposition of electrode metal. The REMS AutoSampler also features a rinse and calibration check station. If occasional rinsing of the REMS electrode is required, it maybe sent to a ri
  10. TEER Research: WPI's Manual and Robotic Systems
    October 11, 2013
    Transepithelial Electrical Resistance TEER measurements is the most convenient, reliable and non-destructive method for evaluating and monitoring the growth of epithelial tissue cultures in vitro. The confluence of the cellular monolayer is quickly determined by a sharp increase in TEER. TEER measurement technology, which was first introduced by WPI in the mid-1980's, has since been perfected and expanded to include a range of TEER related manual and automatic instrumentation, including: EVOM² - Manual TEER measurement of epithelial cells in 24- and 96-well plates REMS AutoSampler - Automated system for High Throughput Screening (HTS) EVOM2 Volt-Ohm Meter
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