When the impedances of the Flex PCB HD-EMG grids remain high for certain channels, you can check if this could be due to a broken channel in the cable.
During the impedance check before the measurement starts, it can occur that one or multiple channels show bad impedances, or 'Not Connected'. There could be multiple reasons why the impedance measurement shows that a channel is not connected. One of the possible causes is the cable.
It is possible to test the cable in the following manner. TMSi advises to use two grids that have not been used before for this test.
- Connect a new grid to SAGA via the HD-EMG adapter cable.
- Connect a snap-on electrode to the patient ground of SAGA.
- Connect SAGA to the PC and open the Quick Recording Application to check the impedances.
- Prepare a small bin of saline water.
- Put the grid and the snap-on electrode in the salted water in the bin, as shown in the picture below. Please make sure that the cable of the HD-EMG grid does not come in contact with the water. The cable of the patient ground is allowed to get wet for a short time at the electrode side only.
- Check if all impedances (including the patient ground) are green. Make a screenshot of the impedances if this is not the case.
- Repeat steps 1-6 with a different grid.
If all electrodes show green impedances during the tests, there might be a different issue underlying the bad impedances. Tips to prepare the subject can be found here.
If during these tests one or multiple channels remain dark red while the others are green, please contact email@example.com or submit a support form. Please include screenshots of the impedances during the test.
Do you have further questions on this topic?