EVOM MANUAL FOR TEER MEASUREMENT

EVOM MANUAL Brochure

Quick Start Guide

EVOM MANUAL Instruction Manual

Software for EVOM-Manual

Python digital output package

EVOM MANUAL firmware upgrade package EVOM Manual Rev 1.5 

Videos

Why Upgrade your EVOM Manual?

 

9 Reasons to Trust WPI's New EVOM™ Manual TEER Measurement Meter

 

EVOM™ Manual Electrode Options

 

Quick Start Guide for the EVOM Manual Home Screen

 

EVOM™ Manual Monitors Cellular Health by Measuring TEER/TER

 

Unboxing the EVOM™ Manual TEER Meter

 

How to Take Voltage Measurements with the EVOM™ Manual

 

How to Take Resistance Measurements with EVOM™ Manual

FAQ

Will the EVOM™ Manual work with Endohm’s?

Yes, but the 99672 adaptor is required or the new EVOM3/EVOM Manual 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 EVOM™ Manual system automatically calculate TEER?

No, TEER measurement requires an area calculation. To compute TEER, multiply 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 cm² = 638.5 Ω- cm². Here are the surface areas generally applicable to different transwell/insert formats: 6 well plate (24 mm inserts) 4.52 cm², 12 well plate (12 mm inserts) 1.13 cm², 24 well plate (6.5 mm inserts) 0.33 cm², 96 well plate (4.3 mm inserts) 0.14 cm². For Automated TEER Measurements, consider using the WPI REMS Automated TEER Measurement System.

 

EVOM™ Manual 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.

 

How should you store the EVOM™ Manual and electrodes if they will be exposed to UV light in a laminar hood for extended periods of time?

Take the EVOM™ Manual out of the laminar hood after use. Next time, turn on the UV inside the hood. Once the hood is disinfected by UV, turn off UV, next spray 70-100% ethanol or isopropanol onto paper towel and wipe the EVOM™ Manual. Do not spray alcohol directly onto EVOM™ Manual.

 

Why am I getting dashes as reading on EVOM™ Manual, even if I have the STX4 electrode inside the sample?

The electrode in the air or partially immersed in the liquid can show dashes since it records unstable read outs. The electrode tip portion (sensing region) must stay fully immersed. You may also notice unstable read outs when the electrode tip is not fully immersed. Make sure to select apical and basolateral volumes so that electrode tip stays fully immersed. You need to use apical and basolateral volumes greater than what is suggested by the insert manufacturer. For example, for Corning-24 well Transwell (example Corning 3470) we recommend minimum 300 µL on the top (apical) and 850 µL on the bottom (basolateral). [These volumes are a little more than the least required for STX4 electrode.]

Here are the steps:

Figure 1: STX4 Adjustment of Electrode Height. Rotate the front ring clockwise so that the electrode can enter to the maximum depth inside the well.

 

Figure 2: STX4 Electrode tip and liquid volume requirements. Make sure the electrode sensing tip (red boxed portions) on both blades stay fully immersed in a conductive liquid, such cell culture media or buffer during measurement. You need to have adequate apical and basolateral volumes to get a stable reading. Since STX4 stays hung, the increased volume must be used to make sure electrode sensing region fully immersed.

NOTE: You must use more liquid volumes than recommended by the insert manufacturer. Insert manufacturer’s recommended volumes will not keep electrode tip fully immersed.

[As mentioned as an example previously, for Corning-24 well Transwell (e.g., Corning 3470) we recommend using minimum 300 µL on top (apical) and 850 µL on bottom (basolateral). These volumes are a little more than the least required for STX4 electrode. You can check visually to make sure the apical and basolateral volumes are adequate to keep the electrode tips fully immersed, and then consistently use those volumes.]

Can increasing or changing sample liquid volumes change my resistance values?

You can expect to see a change of raw resistance values. However, you subtract the blank values (blank Transwell with no cells) from the sample values (Transwell with cells). This way, you subtract the blank value with increased volume from samples with increased volume. Thus, any change of resistance contributed by increased volume is omitted. Consistently use the same volumes for all your samples in an experiment.

 

Is there an electrode cleaning or maintenance instruction that I can follow?

Below are the steps that can be followed for STX4 cleaning or maintenance. Make sure you use enough liquid levels during cleaning or maintenance at least up to the red boxed region

1. Rinse with sterile DI water/buffer.
2. Optional step: Quick dip in 70% ethanol or isopropanol and quick dip in DI water/buffer.
3. Use the electrode for measurements.
4. Optional step in between measuring samples: Quick dip in 70% ethanol or isopropanol and quick dip in DI water/buffer.
5. After measurements soak/immerse electrode tips in 70% isopropanol or ethanol for 5-10 minutes.
6. Rinse with DI water. Let it air dry. Store electrode dry and in a place away from light/minimal light.
7. When used frequently, every week soak electrode tips in 1% Tergazyme for 15 minutes. Follow by rinse with DI water.
8. Use for measurements.

 

Why do my readings appear to be drifting?

Drift refers to readings that continuously increase or decrease significantly (either voltage or resistance) over time. Example: At 1000 Ω, the reading is increasing 100 Ω/ minute. (A drift of 10 Ω/minute is acceptable.) Excessive drift may be caused by changes in the pH or temperature, or the electrode needs cleaning.

There are a few things that can be a possible cause of this drift.

• Ensure that the electrodes are fully immersed in culture media solution, and the fluid temperature in the plate is consistent by equilibrating at room temperature or using a plate warmer.
• Another common cause of drift is the electrode tips may have deposits of cell culture media constituents
• The electrode (tips) requires enzymatic cleaning (Tergazyme or Enzol) periodically up to 1x per week depending on the use.
• Handheld electrodes also must be kept as motionless as possible during a measurement.
• Excessive movement will cause the measurement to fluctuate.
• Additionally, in a 5% CO₂ environment, a loss of CO₂ causes the media pH to change, and the resistance reading may change. This is mainly applicable in the context of continuous measurement for an extended period (hours, as compared to a few minutes).

 

Why are my electrode readings unstable?

If you experience instability at 500 Ω, the reading jumps from 450 to 550 Ω and does not settle down (an instability ±5 Ω is acceptable in the 500 Ω range). In the higher ranges, up to ±1000 Ω is acceptable at the 100K range. Electrodes showing instability may require enzymatic cleaning.

• The most common causes of reading instability can be fixed by fully immersing the tips in solution or performing enzymatic cleaning.
• The electrode tips are not fully immersed in adequate conductive liquid (media or buffer). Add extra liquid to bring the liquid level up to the electrode tips. (Use consistent apical and basolateral volumes to make consistent comparisons.) The electrode tips (sensing region) may have deposits of cell culture media constituents, this can be resolved with enzymatic cleaning.

 

How do I check whether my EVOM^TM Manual system is functioning properly?

• Use the 1000-ohm test resistor to test and calibrate the EVOM meter itself. Verify the screen display shows a 1000 ohm reading +/- 1 ohm. Refer to the user manual for more specifics on calibration.
• To test the function of your electrode, a KCl resistance test is used. Prepare 40-, 80- and 160-mM concentrations of KCl using deionized (DI) water. As the KCl solution concentration doubles, the resistance reading should decrease by around half.
• If you are experiencing drifting resistance values with 80 and 160 mM KCl solutions, ensure that:
  • Electrode tip portion or sensing region is fully immersed in the conductive liquid (media or buffer) during measurement.
  • Electrode needs cleaning. A regular cleaning/maintenance of the electrode is strongly recommended and needed for functional longevity of the electrode.

 

Are there any other electrode handing instruction that WPI recommends?

	Do NOT hold the electrode by the cable. It can physically break the internal connections gradually.
	Hold the electrode by the arrowed region (plastic).
	Limit liquid immersion or liquid spray level somewhere up to here (maximum). You do not want the liquid to get inside and reach up to internal the cables or connectors that’s why. You can wipe with the rest of the electrode with a paper towel sprayed with isopropanol or ethanol (do not spray directly).

 

 

This unit conforms to the following specifications:

Type	Descriptions
Tissue Sampling Frequency	12.5 Hz
Sample Averaging	20 samples per second
Resistance Ranges	0 to 10,000 Ω  0 to 50,000 Ω  0 to 100,000 Ω +5%
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)
Resistance Accuracy	0.1 Ω (under 200 Ω), 1 Ω (over 200 Ω) 0.1%  100,000 Ω ± 2 μA (to 105 KΩ)
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
Current Levels	10,000 Ω ±10 μA 50,000 Ω ± 4 μA 100,000 Ω ± 2 μA Auto mode 1 to 100,000 Ω auto current 2 μA, 4 μA, 10 μA
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
Certifications	CE

** mAH means milliamp hours.

System Components

What is included with the EVOM™ Manual	QTY
evm-mt-03-01 : EVOM™ Manual Epithelial Volt Ohm Meter	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 EVOM Manual Electrode Adapter is sold separately. The STX2, STX3 and all STX100s require the use of this adapter with the EVOM3 or EVOM Manual.