NI DAQ problem

[李程]

Dear All,

As we cannot get any signals from the cultured MEA, now we are checking every components in the system.

We tried again to input sine wave signals from the SCB-68A box and recoreded using NR and NI max separately. Since the ground of the signals are connected to AI sense, we assum that it should be NRSE. Using this mode, we can see the signals correctly in NI max but in NR, as long as the signal was input from the channel of the DAQ card, all other channels of the same card showed similar signals (show as figure), which should not be shown at all theoretically.

Then we trid to show the signals as differentiation signals in NI max and found similar results as what was shown in NR. Does this mean that in NR, the signal was treated as differentation signals rather than NRSE signals? Or is there any settings in NR or DAQ card or SCB-68A box that we should do before signal collecting? The DAQ card we are using is PCIe-6353.

Thank you.

[Jon Newman]

All signals should be single ended and referenced to the ground pad in the MEA chamber. Obviously, if the breakouts are miswired, then this will not be the case.

This looks like mains interference. I'm going to assume that the vertical scale is not correct because you did not set the amplifier gain in settings. You have 250 ms window and i count 12-13 peaks per window which puts the period at

250ms / 12.5= 20 ms 

so 50 Hz. I'm assuming you are outside the US.

Where is your amplifier located? How is your system powered? How have you arranged your ground connections?

Jon

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Jonathan Newman

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http://www.mit.edu/~jpnewman/

[Jon Newman]

Another thing. On our rigs, we have a single channel didicated to ground. That would be electrode [1,5] in column row fomat, or 33 on the NeuroRighter screen. That electrode, which corresponds to the ground pad on the MEA, is tied right to the analog reference port on the breakout, and therefore should be dead quite. In your case, it looks like its floating. What are you using to tie your bath the analog reference?

[李程]

Hi Jon,

Thank you for the reply. For the figure, we disconnected the amplifier and input the sine wave signal ( 10Hz, +/-0.5V) through the breakout box directly to test the DAQ card. The signal was added to only one channel (between the AI 0 and AI sense in breakout box 1) which should be channel 52 in NR screen. However, as you can see from the figure, all the left part of the NR screen show similar signal outputs. Is this because of settings or because of the open ends for the channels?

We didn't find the software or hardware settings for the  signal mode (single referenced ended/differential/none refereneced signle ended). Is this single referenced ended mode a default setting for NR software?

Moreover, we tested the output of MEA neuron culture with whole system connected correctly according to the website. We put the amplifier in a incubator (37c, 20% humidity, 5% CO2). We powered the system using a DC power supply (+/- 6V) through the interface PCB.

For the gounding of the connections, we followered the MEA manual. We have two types of MEA (with/without internal reference electrode). For MEA with internal reference, we connected the channel (33 on NR screen) to MEA amplifier ground. For MEA without internal reference, we used an external Ag wire supplied by MCS to connect the MEA ground with culture media. What's the difference of the four goundings (1,8,57, and 64 on NR screen)? Is the additional ground when internal reference is used (33 on NR screen) different from these four goundings?

We still cannot obtain any signals even though we can see the neurons grow well on MEA using microscope. Do you think the current issue relevant?

Thank you.

On Saturday, November 21, 2015 at 1:34:38 AM UTC+8, Jon Newman wrote:

Another thing. On our rigs, we have a single channel didicated to ground. That would be electrode [1,5] in column row fomat, or 33 on the NeuroRighter screen. That electrode, which corresponds to the ground pad on the MEA, is tied right to the analog reference port on the breakout, and therefore should be dead quite. In your case, it looks like its floating. What are you using to tie your bath the analog reference?

On Fri, Nov 20, 2015 at 12:24 PM, Jon Newman <jpne...@mit.edu> wrote:

All signals should be single ended and referenced to the ground pad in the MEA chamber. Obviously, if the breakouts are miswired, then this will not be the case.

This looks like mains interference. I'm going to assume that the vertical scale is not correct because you did not set the amplifier gain in settings. You have 250 ms window and i count 12-13 peaks per window which puts the period at

250ms / 12.5= 20 ms 

so 50 Hz. I'm assuming you are outside the US.

Where is your amplifier located? How is your system powered? How have you arranged your ground connections?

Jon

On Fri, Nov 20, 2015 at 6:18 AM, 李程 <lche...@gmail.com> wrote:

Dear All,

As we cannot get any signals from the cultured MEA, now we are checking every components in the system.

We tried again to input sine wave signals from the SCB-68A box and recoreded using NR and NI max separately. Since the ground of the signals are connected to AI sense, we assum that it should be NRSE. Using this mode, we can see the signals correctly in NI max but in NR, as long as the signal was input from the channel of the DAQ card, all other channels of the same card showed similar signals (show as figure), which should not be shown at all theoretically.

Then we trid to show the signals as differentiation signals in NI max and found similar results as what was shown in NR. Does this mean that in NR, the signal was treated as differentation signals rather than NRSE signals? Or is there any settings in NR or DAQ card or SCB-68A box that we should do before signal collecting? The DAQ card we are using is PCIe-6353.

Thank you.

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Jonathan Newman

Postdoctoral Fellow, MIT

http://www.mit.edu/~jpnewman/