Resources

Frequently Asked Questions

Is ECIS an acronym?
Yes, it stands for: Electric Cell-Substrate Impedance Sensing
How is ECIS pronounced?
ECIS - (ë'sis) n. adj.
Does ECIS require labels?
ECIS is a completely label free measurement.
Do the cells sense they are being monitored?
The AC current used to monitor the cells is 10 X below their ability to sense any current. It's as if you are eavesdropping on the cells.

ECIS Measurement

What is impedance?
Electrical impedance is a measure of the opposition to a sinusoidal AC current. Impedance extends the concept of DC resistance to AC circuits. It describes not only the amplitude of the voltage and current, but also the phase of the voltage relative to the current.
What is complex impedance?
answer
What does just resistance measure?
answer
What does just capacitance measure?
answer
Why do you use an AC current?
answer
What does the system measure?
The ECIS system measures the change in impedance as cells cover a 250um diameter gold electrode and block the current flow.
What is micromotion?
The intricate movement, and unique ruffling of the cell.

Applications

Can I coat the electrode arrays with proteins?

Yes, you can coat the wells with proteins, this is quite common. Our suggested protocol is Make up a solution of the protein at 200 micrograms per ml in 0.15M NaCl. The use of phosphate buffer can seriously interfere with the adsorption of some proteins and should be avoided. If a buffer is essential, a mild Tris solution (e.g. 0.01M) is OK.

To coat the electrode, simply place a small amount of the protein solution in the bottom of the well and allow it to remain in place for 10 minutes or more. If the protein is valuable, with the 8W1E arrays, it is only necessary to coat the small active electrode (250 micrometer diameter), and as little as 10 microliters or less can be carefully applied to this very small spot at the bottom of each well. Once the adsorption has taken place, an approximate monomolecular layer of the protein will be coating the surface and will not be removed by rinsing. If desired you and rinse the protein solution from the well with sterile medium, PBS, saline or water. Medium can now be added and inoculation begun. The effect of adsorbed proteins sometimes produces dramatic changes in the dynamics of cell attachment and spreading.

If the protein is in plentiful supply, e.g. gelatin, solutions of 1 mg/ml can of course be used, but again avoid phosphate buffers and rinse the wells before inoculation. In either case, we do not recommend drying the protein solutions in place as it can foul or damage the electrodes.

Does "wounding" damage the protein coating?
No. One of the advantages in using ECIS over traditional scrape methods is the facts that the protein coat is unaffected by the current. With traditional methods the protein is scraped off with the cells.

Trouble shooting

My cell layer is not growing to confluence or its taking a long time.

Be sure that you are seeding your cells at the appropriate density, we recommend adding 400 µL volume of a 5 x 10^5 cells/ml suspension per well.

Protocol: Pipette medium gently into the well and allow to stand for 60 minutes in incubator. This step wets the electrodes and limits wicking of medium up well sides when cells are placed in wells. Using a confluent T-25 flask, draw off medium and trypsinize cells. Once cells have rounded and slide off flask re-suspend in 3 ml's fresh medium Withdraw 200µl of medium in the well and add 400µl of a 2.5 x 105 cells/ml suspension (105 cells total) OR You can choose to leave the 200µl of medium in the wells and add an additional 200µl of 5.0 x 105 cells/ml suspension.

Note: If you choose this method, be certain to carefully pipette the medium in the well up and down several times to assure a uniform coating.

Try treating your wells with cysteine before adding cells. Pdf protocol

If you are still having problems contact us toll free: 1-866-301-ECIS (3247)

One of the wells on my array is reading a flat line.

This may be due to a bad connection between the gold pogo pins and the array. Be sure that the pogo pins are making contact with the gold pads on the array, this may take repositioning the array.

Be sure to gently tighten the clamp to the array. Light contact is all that is needed to carry the current.

Check to see that there are no scratches in the gold pads of the array. You can avoid scratching the array by gently tightening the clamp, as well as loosening the clamp, making sure the pogo pins are not making any contact with the array before removing it from the array holder.

You may also try wiping the pogo pins off with a kimwipe to be sure they are not dirty.

My pogo pins are stuck.

The pogo pins only tend to get stuck within the cylinders they are housed in when they have gotten to wet. The corrosion occurs in an overly moist environment, and or when medium is continually splashed on or around the pads of the array.

Please contact Applied BioPhysics for additional help, you may have to have the pogo pins replaced. 1-866-301-ECIS (3247)