fECG acquisition

[bogdanhu]

Currently, i am taking my measurements using BIOPAC MP150 , but the results are very noisy .

I got in possesion of a NI USB-6009 and LabView 2011 and I was wondering if I could get better results on NI.

fECG is quite small and I need good SNR .

Any suggestion ? Would be there a better option  ?

[ZJ.Gu]

Hi,

Is this fECG representing fetal ECG? If yes, how you acquire it using BIOPAC? What's the sensor?  I think NI USB 6009 is just for data acquisition. It does not have any noise reduction features.

Thanks!

[bogdanhu]

yep. fetal ECG.

Biopac has the acquistion device though modules and leads and it is connected directly to the PC . The module has a biopotential amplifier. The main problem is the PLI interference and the leads noise.

Due to the fact , that i get a lot of noise using this method , i was thinking to check a alternative to Biopac . I  got the NI 6009 and i am thinking a method to use the electrods ( Ar+Cl) that i use for BIOPAC. It is possible to have  better results using NI devices?

[weny]

Have you checked your signal output from NI USB 6009 using an oscilloscope? If the noise from there is fine, then you probably need to check your cable. Most time the cable introduces noise if your device doesn't have a good filter in it. You can make your cable as short as possible like curl it up to reduce the noise from the enviroment. Also, remove all other devices around, even a digital multimeter...

[bogdanhu]

I have not make yet a test with NI devices. The main problem is that the useful signal has about 10 uV , so i need noise smaller than that.

My question is if NI 6009 can offer me this or should i find a better acq card/device.

[ZJ.Gu]

Hi,

I don't think USB 6009 could meet your requirement. Please check out the specification - https://www.ni.com/en-us/support/model.usb-6009.html.

Usually, if your input signal is only about 10uV, you need signal conditioning before you wire into NI DAQ hardware.

Thanks!

[weny]

You can get 1V signal output from NI6009, then use a voltage divider to attenuate the signal to 10uV. You aslo need to add a shield box (made by steel) to your attenuator to reduce the noise. Even that, it is still hardly to avoid the noise from resistors and the power line. But I guess your device might be able to catch that signal after this.

If you try to output 10uV signal directly, your signal will be buried by the noise. Check your NI 6009 output first.

[Daniel_H1]

Hi bogdanhu,

When working with ECG cables, if you twist the cables around each other you can eliminate some of the differential noise.

Here is a great guide for addressing noise in analog signals: https://www.ni.com/en/shop/data-acquisition/measurement-fundamentals/field-wiring-and-noise-consider...

[Steve.J]

You cannot acquire ECG (or any biopotential) directly with the USB-6009.  It does not have the proper inputs to work with biopotential surface electrodes.  You will need an biopotential amplifier (ECG amplifier) before the USB-6009 to perform the signal conditioning and amplification necessary to get a good clean signal. In addition, the NI-6009 does not have isolated inputs and provides no protection against shocks or other safety hazards.

Please read this article for more details and suggested sources for amplifiers:  https://forums.ni.com/t5/Biomedical-User-Group-Documents/Sources-for-biosignal-amplifiers-sensors-el...