Advise about DAQ..experts please get involved

[Yamaeda]

Without amplification that might be hard. Looking at 16-bit AI you get a resolution of about 70 microV, with a 18-bit solution you'll get 0.8 microvolt resolution which should be enough (and sample speed should be enough with 625 kS/s). 18-bit resolution cost abit more, so scale the signal or get more sensitive gear, basically.

https://www.ni.com/en-us/support/model.pci-6280.html

That's the first example i could find, browse around, there might be other solutions.

/Y

[Bildavid]

 Hi all

Yes there is amplification stage of course . but i meant to say that the electrical signal taken from the patient through gel electrodes is in the range of 70 microvolts . after that there is 3 amplification stages that turn the signl from microvolts range to millivolt. ( 1 mV approximately )

Tlaking about the sampling frequency .. well i guess that when programing m gonna set sampling frequency to be from 1000 samples to 4000 samples depending on the results.

Thank you so much !!

[JÞB]

Yamaeda.  That's not quite right.  The Minimum range accuracy for an 18 bit is probably going to be the driving factor.

Now let us discuss sample rate.  This is a bio sensor  human bodies are just not that fast! a 512 Hz sample rate is twice the speed of most state of the art implantable med devices Anything faster than that is a complete waste of processor since nothing that fast is affecting cell chemistry.  slow it down to keep the data meaningful. 

[Bildavid]

Hi Jeff·Þ·Bohrer

okay . i understand about the sampling frequency . thank you so much . okay . do you advise me of NI DAQ6008 or 6009 ??

[JÞB]

with the 6008 in a -1 to +1 volt range your accuracy will be about 37.5mV with about 0.4mV resolution.  That doesn't sound ideal for a 1mV signal