How to Use the NanoZ with Plexon Adaptors to Measure Impedance

The nanoZ can be used with custom designed adaptors to test the impedance of all electrodes offered by Plexon. The information below describes how to measure the impedance of electrodes with Omnetics connectors. Information specific to each Omnetics connector type can be found under the appropriate tab.

Open the nanoZ software and make sure that the drop down menus for the adaptor and probe say “No adaptor” and “Probe not selected.”

The nanoZ measures impedance relative to a return electrode. After an electrode array has been implanted, the impedance is typically measured relative to one of the ground electrodes within the array. Prior to implantation, the impedance of the ground electrodes themselves (and the other electrodes) can be measured relative to an external electrode that is not part of the array. This is useful for verifying the integrity of the ground electrodes. To do this both the G1 and G2 jumpers should be set in the 35 and 36 positions (ground electrode 1 = nanoZ channel 35 and ground electrode 2 = nanoZ channel 36) and connect an external return electrode to the point labeled EXT on the circuit board. The impedances of the ground electrodes in the array will show up as channels 35 and 36 in the nanoZ impedance file. Note that the ground electrodes typically have a low impedance value. This configuration is typically used for measuring the impedance of the array in a beaker of saline, and especially for verifying the integrity of the ground electrodes, prior to implantation.

To measure impedance relative to one of the ground electrodes within the array, position ONE of the jumpers in the RET (return) position. This configuration is typically used for in vivo impedance measurements of chronically implanted electrode arrays. There are two possibilities for the pair of jumpers to be set. G1 can be in the RET position and G2 can be in the 36 position as shown above (ground electrode 1 = nanoZ return, ground electrode 2 connected to impedance channel 36). In this configuration, all electrodes including Ground 2 (whose impedance will appear as channel 36 in software) are measured using Ground 1 as the return path for current. This means that the integrity of Ground 2 can be checked in vivo.