Epithelial Volt/Ohm (TEER) Meter 3
TEER measurement with automatic data logging
- Low noise design offers greater resolution and accuracy
- Automatic 20X sample averaging improves accuracy and stability
- Adjustable fixed measurement currents (2, 4 or 10 μA)
- Resistance auto ranging from 1 Ω to 100,000 Ω or with three fixed current ranges
- Reliable low current, low voltage design prevents metal ion transport
- Fast resistance stabilization on low levels under 200 Ω with resolution to 0.1 Ω
- Ergonomic tilt stand for low glare operation
- Graphical display of popular plates (6, 12, 24, 96) for trend analysis
- Display shows the most recent set of parameters
- Automatic plate indexing operation with or without control well subtraction for resistance and potential difference (PD) measurements
- Continuous data logging via USB (PC, Mac, Linux)
- Saves date stamped data to a spreadsheet readable file on a USB drive
- Upgradable firmware
Next Generation Epithelial Volt Meter
EVOM3 Monitors Cellular Health
WPI's EVOM system is popular in the research community, and it is commonly used for the evaluation of mammalian cellular health by measuring transepithelial/transendothelial electrical resistance (TEER or TER) of cellular layers.
EVOM3 works on the same basic principle as older EVOM models (EVOMX, EVOM and EVOM2). It has advanced features for performing experiments more easily. With the new touchscreen display you can now STORE DATA as Microsoft® Excel files on a USB flash drive. Just remove the flash drive with all your recorded data from the EVOM3 and plug it into a computer to access and plot your data. It is as simple as it sounds.
TEER: Transcellular & Paracellular Pathway of Ion or Electrical Current Flow
Ions and electrical current can be transported through the cells (transcellular) and through the space between adjacent cells (paracellular) as depicted in the image below.
The dotted lines show the transcellular pathway of ion or electrical current flow. The solid lines demonstrate the paracellular pathway of ion or current flow.
EVOM3 TEER Measurement Basic Working Principle
Electrical resistance (i.e., TEER) of a cellular layer is the inverse presentation of the electrical conductance through the cellular layer. A high TEER value of the cellular layer is indicative of an intact cellular monolayer and suggests low or restricted permeability of ions and molecules (i.e., low conductance). Similarly, a decrease in the TEER value suggests a compromised barrier function and indicates increased permeability. Tissue permeability studies require a confluent cellular layer, and TEER measurement is gennerally used to confirm the formation of a confluent monolayer.
Initially, 24 hours after cells eeding transwell, TEER values are generally low, because the current passes can pass easily between the cells. Over time, the cells multiply and start covering the gaps. Finally, a confluent cellular monolayer is formed. At that point the permeable membrane is fully covered with cells and does not allow easy passage of electrical current. This results in a high TEER value.
TEER Measurement of Leaky & Tight Cell Types
TEER values of confluent cellular monolayers can vary depending on the cell type. Monolayers of certain cell types (e.g., cell type A), which normally show low TEER values, generally have relatively leaky tight junctions. Monolayers of other cell types (e.g., cell type B) show high TEER values, and these cell types are known to have tight tight junctions. Ions and molecules are known to pass rather easily across leaky cellular layers as compared to tighter cellular layers.The presence of more transcellular ion channels on cells can further allow easier flow of ions or electrical current through the transcellular pathway, which can additionally lower TEER values.
Cell type A allows greater amounts of current and ions to pass between the cells and yields a low TEER value. With its tighter junctions, cell monolayers of type B cells will show a higher TEER value. While both monolayers are confluent, the TEER resistance values can be markedly different based on the nature of the cells themselves.
Why Choose WPI's EVOM System?
WPI was the pioneer in introducing the simplified TEER measurement technique using EVOM, and to date WPI's EVOM system remains the most popular device for measuring TEER values in transwells. The EVOM3 is the newest version of epithelial volt meters, with several advanced features. The EVOM3 has a touchscreen interface that makes it simple to use. TEER measurement using an EVOM is a non-invasive method of monitoring cellular health. The EVOM3 with the new STX2PLUS electrode offers more accurate sample analysis and quick, simple data storage features using a USB flash drive.
For quantitative sample analysis with higher accuracy and easy data storage, consider EVOM3. The non-invasive method of EVOM3 detection allows the same sample to be used for other experimental analyses.
EVOM3 TEER: Key Applications
Here are three applications where TEER measurement is commonly used. When measuring the cellular barrier function, the rise of TEER values generally correlates with increased barrier function. Similarily, elevation of the TEER value to the maximul level can indicate that the cellular layer has reached confluence. Cellular cytotoxicity can be evaluated by measuring TEER. High TEER values indicate a healthier cellular layer. As the cells die, gaps in the cellular layer can form, and the TEER value can drop.
EVOM3 TEER: Emerging Application Fields
WPI's EVOM system has been extensively used to study in vitro 2-dimensional (2-D) or 3-D tissue health and function. In recent years, for high throughput drug screening and to study diseases, more research fucus has been given in creating 3-D in vitro tissues that resemble in vivo tissues and show consistent functional properties. TEER Measurement is used as one of the methods to evaluate and compare how closely in vitro tissues can mimic in vivo tissues consistently. EVOM3 can be used in 3-D in vitro models, such as the Blood Brain Barrier (BBB), Ling Virus Infection, and Intestine, Kidney and Liver tissues. The References section lists a few selected publications.
Short videos highlight some of the key new features of the EVOM3. Click on the VIDEOS tab on this page to see all the EVOM3 videos.
More on Epithelial Physiology
WPI offers a line of products for the study of epithelial physiology including a variety of electrodes, the EVOM meters and the automated robotic system for high throughput screening (HTS). Get the details on the electrode options in the article "How To Select Electrodes For Making TEER Measurements."
- Eliminates errors and reduces experimental processing time
- Auto data logging eliminates the need to track data by hand
- The small footprint allows more bench space
- Easy calibration and verification
- Footswitch for hands-free recording
- Prevent data loss with auto save and data recovery when battery is low
- TEER is easily computed by applying a unit area formula to the resistance
- Measure epithelial or endothelial tissues for confluence, TEER and potential difference
- Permeability, conductance and drug studies
- Continuous digital monitoring of a target membrane
- Common studies
- Blood-brain barrier transport
- Lung epithelial tissue studies
- Intestinal tissue studies
- Skin studies
EVOM3 For Teer Measurement
The EVOM3 delivers improved workflow efficiency, more stable and repeatable measurements versus traditional Trans Epithelial Electrical Resistance (TEER) meters. Providing users with vital feedback during experiment measurements, the EVOM3’s large screen offers a range of informational views. The new graphical displays for trend analysis and measurement values helps scientists deliver simple, stepwise methodology during experimental measurements. The touch screen interface provides users an intuitive, easy-to-use menu for configuration.
Eliminating the need to log data by hand, the EVOM3 writes the resistance or voltage information to a USB drive in CSV format for easy transfer to spreadsheets and data analysis programs. When used with the footswitch it enables handsfree recording of measurements.
At the heart of the EVOM3 is our latest processor and circuitry, providing users with quick, easy and reliable readings due to its fast stabilization, automatic twenty times sampling average and low noise design. The auto ranging resistance feature allows for fast resistance measurements, and an over-range display feature eliminates false readings. The EVOM3 has adjustable current levels in three fixed ranges with two lower ranges for sensitive membranes and high resistance ranges up to 100 KΩ.
TEER Measurement Electrode
The STX2-PLUS electrode was designed for easy insertion into many 24-well plates. It is location re-placeable in the insert for repeatable and consistent measurements. The new shielded electrodes are now designed to minimize electrical interference and to be more easily maintained.
- STX2-PLUS new electrode designed for 12 and 24-well plates.
- Weighted self-standing electrode for hands-free stable measurements
- Shielded cable to minimize electrical and cell phone interference
|What is included with the EVOM3||QTY|
|EVOM3 Epithelial Volt Ohm Meter||1|
|STX2-PLUS Electrode set||1|
|300749 USB drive 32 GB (Used for storage. Also contains a Python 3.8 program for continuous digital monitoring of a target insert).||1|
|503535 USB cable||1|
|99673 Calibration kit, 1000Ω Test Resistor||1|
|803025 A/C power cord and charger||1|
|13142 Foot switch||1|
NOTE: A 99672 EVOM2 to EVOM3 Electrode Adapter is sold seperately. The STX2, STX3 and all STX100s require the use of this adapter with the EVOM3.
- Keyed electrode base for repeatable placement gives more consistent results, eliminating the need for multiple readings.
- Easy to maintain
How Does the EVOM3 Work?
Confluence of a cellular monolayer is determined by an increase or a plateau in tissue resistance detected using the unique electronic circuit of the EVOM3 and the new STX2-PLUS electrode. The EVOM3 qualitatively measures cell monolayer health and quantitatively measures cell confluence. The EVOM3 produces a low AC current that avoids electrode metal deposits and adverse effects on tissues which can otherwise be caused by higher DC currents. The EVOM3 uses low current and voltages and is designed for non-destructive testing for epithelial monolayer confluence in cell cultures. In addition, resistance readings are unaffected by membrane capacitance or membrane voltage. The accuracy and repeatability of the EVOM3-STX2-PLUS system makes this instrument ideal for permeability, PD and other detailed membrane studies.
Electrodes For TEER (Epithelial) Measurement
|STX2-PLUS||Replacement Electrode Set|
|STX2*||Replacement Electrode Set (Requires 99672 for use with the EVOM3)|
|STX3*||Adjustable electrode set for shallow wells, 5-9 mm depth|
|3993*||2 mm Adapter for EVOM2|
*(Requires 99672 for use with the EVOM3)
ENDOHM Chambers For Endothelial/Epithelial Measurement
NEW EndOhm chambers include the EVOM3 cable 99916.
|ENDOHM-6G||EndOhm for 6 mm culture cup (24 wells per plate)|
|ENDOHM-12G||EndOhm for 12 mm culture cup (12 wells per plate)|
|ENDOHM-24G||EndOhm for 24 mm and Costar Snapwell cup (6 wells per plate)|
Software for EVOM3
EVOM3 firmware upgrade package EVOM3 Rev 1.5 (current release)
- Will the EVOM3 work with Endohm’s?
Yes, but the 99672 adaptor is required or the new EVOM3 cable 99916.
- Why would I want to use the blank function?
The blank feature is used when you want to subtract out any measurement that is not from the membrane, such as the electrode and fluid resistances.
- Does the EVOM3 system automatically calculate TEER?
No, TEER measurement requires an area calculation. To compute TEER, divide the measured resistance by the appropriate surface area (below). For example, a 12 mm insert measures 565 Ω, the TEER is 565 Ω/1.13 or 500 Ω. 6 well plate (24 mm inserts) 4.53 cm2, 12 well plate (12 mm inserts) 1.13 cm2, 24 well plate 6.5 mm inserts) 0.3316 cm2, 96 well plate (4.3 mm inserts) 0.143 cm2.
- EVOM3 data is stored automatically when the last well is reached. How do I store the data when I only want to measure 8 of 96 wells?
Clear any data in memory by opening settings, store menu then press new plate, that will clear any prior readings. Return to the main screen, open the preview screen, select each well to measure (the selection turns green), place the electrode, then measure. When you’re done measuring the selected wells, open the settings, press the store screen menu, then press store new to save the plate data to the USB drive.
This unit conforms to the following specifications:
|Tissue Sampling Frequency||12.5 Hz|
|Sample Averaging||20 samples per second|
|Auto Mode||1 to 100,000 Ω auto current 2 μA, 4 μA, 10 μA|
|Resistance Resolution||0.1 Ω (under 200 Ω); 1 Ω (over 200 Ω)|
|Voltage Resolution||0.001 V, 0.1 mV|
|Accuracy Resistance||0.1 Ω (200 Ω); 1 Ω (above 200 Ω)|
|Accuracy voltage||± 0.1 mV|
|Display Update Rate||0.5 seconds|
|Battery||3.7V Li-ion 2500 mAh**|
|Charging Period||5.5 hours (power off); 6 hours (run time)|
|Charge Current||200 mA|
|Power Consumption||~250 mA|
** mAH means milliamp hours.
Pongkorpsakol, P., Turner, J. R., & Zuo, L. (2020). Culture of Intestinal Epithelial Cell Monolayers and Their Use in Multiplex Macromolecular Permeability Assays for In Vitro Analysis of Tight Junction Size Selectivity. Current Protocols in Immunology, 131(1). https://doi.org/10.1002/cpim.112
Stanifer, M. L., Rippert, A., Kazakov, A., Willemsen, J., Bucher, D., Bender, S., … Boulant, S. (2016). Reovirus intermediate subviral particles constitute a strategy to infect intestinal epithelial cells by exploiting TGF-β dependent pro-survival signaling. Cellular Microbiology, 18(12), 1831–1845. https://doi.org/10.1111/cmi.12626
Meenach, S. A., Tsoras, A. N., McGarry, R. C., Mansour, H. M., Hilt, J. Z., & Anderson, K. W. (2016). Development of three-dimensional lung multicellular spheroids in air- and liquid-interface culture for the evaluation of anticancer therapeutics. International Journal of Oncology, 48(4), 1701–1709. https://doi.org/10.3892/ijo.2016.3376
Ferguson, M. C., Saul, S., Fragkoudis, R., Weisheit, S., Cox, J., Patabendige, A., … Fazakerley, J. K. (2015). Ability of the Encephalitic Arbovirus Semliki Forest Virus To Cross the Blood-Brain Barrier Is Determined by the Charge of the E2 Glycoprotein. Journal of Virology, 89(15), 7536–7549. https://doi.org/10.1128/jvi.03645-14
7 Reasons to Love the New EVOM3 for TEER Measurement
Great New Features of the EVOM3
The EVOM3 TEER Measurement System enables researchers to carry out experiments more efficiently by improving the workflow, and increasing the stability and accuracy of readings over that of the EVOM2. If you prefer to read the details, see the article "Why Choose an EVOM3 over an EVOM2."
EVOM3: What's New?
Compact and Lightweight - This is a comparison between the EVOM3 and the EVOM2. At less than 1 lb., the EVOM3 is lightweight and portable. It has a sleek design with a touchscreen interface.
Smart Data Display and Foot Switch Control - See how easy it is to setup and use the foot switch to collect data.
Data Storage on USB Flash Drive - Save data as a Microsoft Excel files on the USB flash drive with the touch of a button. The data file can be accessed on a computer by plugging in the flash drive to a USB port.
Improved Electrode Design - Compare the STX2 electrode and the NEW STX2-PLUS electrode. The new electrode stands vertically on the well plate, ensuring stable and consistent readings.