[Eeglablist] EEG device inquiry

[Lin, Hong]

Hi Makoto and Arno,

I appreciate all the information circulated here. This helps me a lot.

Thanks,
Hong


-----Original Message-----
From: eeglablist <eeglablist-bounces at sccn.ucsd.edu> On Behalf Of Makoto Miyakoshi
Sent: Thursday, January 16, 2020 10:49 AM
To: eeglablist at sccn.ucsd.edu
Subject: Re: [Eeglablist] EEG device inquiry

Dear Arno and David,

> Keep in mind that the amplifier Makoto pointed at on eBay collects 
> data
with 16-bit precision while usually for research purposes it is better to acquire data with 24-bit precision.

Thank you for your comment. That's a good point. I also have some comment on it.
The resolution in voltage is not only determined by bit depth but by also dynamic range since it is (dynamic range)/(bit depth), and dynamic range is often a trade-offs by bit depth. The manufacturers sometimes describe resolution in voltage unit, but not always--so you may need to calculate it by yourself.

In any case though, the bottom line is that every amplifier has thermal noise floor which is probably practically 1 microV in good cases, and even larger is electrode contact noise around 3-5 microV. Having too high resolution relative to this noise floor does not seem to help. See Huigen (2001) 'Noise characteristics of surface electrodes' you can find it online.

Makoto


On Thu, Jan 16, 2020 at 2:21 AM Delorme, Arnaud <adelorme at ucsd.edu> wrote:

> Dear Lin,
>
> Keep in mind that the amplifier Makoto pointed at on eBay collects 
> data with 16-bit precision while usually for research purposes it is 
> better to acquire data with 24-bit precision. Also, inexpensive 
> amplifiers often do not acquire data simultaneously on all channels 
> (they have one amplifier for all data channels and acquire one channel 
> then another etc…). This is not the end of the world but something to know and it has consequences.
>
> Major companies in the field are (in no particular order): BIOSEMI, 
> Brainamps, Neuroscan, Phillips Neuro, ANT, gTek etc… They offer more 
> expensive solutions, and this is not necessarily due to the complexity 
> of the technology, but primarily to the very low volume (only a couple 
> of amplifiers sold per month).
>
> Also, as important as the amplifier (if not more important) is the cap 
> and the electrodes you use. Do not skimp on that.
>
> Best wishes,
>
> Arno
>
> > On Jan 14, 2020, at 11:38 AM, Makoto Miyakoshi <mmiyakoshi at ucsd.edu>
> wrote:
> >
> > Dear Lin,
> >
> > I have no conflict of interest with any of EEG amp manufactures 
> > (well, I have some of my friends in BrainVision, but they don't pay 
> > me for that.) That being declared, I like NVX52 from Mitsar. It has 
> > 48 ch EEG and the prices is around $10k including several caps and 
> > electrodes. I should not say exactly how much it is because it all 
> > depends. Find multiple distributors of this product and compare 
> > prices. One time I even found it on eBay (there still is
> >
> https://www.ebay.com/itm/New-Mitsar-EEG-201-Amplifier/264270331268?has
> h=item3d87bd3d84:g:ph4AAOSwdm1bGO26
> )
> > but this is not NVX52. If you are based on US, I know one distributor.
> > Contact me if you are interested.
> >
> > Good luck!
> >
> > Makoto
> >
> > On Mon, Jan 13, 2020 at 11:20 PM Lin, Hong <linh at uhd.edu> wrote:
> >
> >> Hi Folks,
> >>
> >> I don't have professional experience in EEG data collection. I now 
> >> have
> a
> >> task to choose the best product to purchase with $10,000 budget. I 
> >> considered AdInstrument PowerLab, which goes beyond my budget a 
> >> little
> bit.
> >> It does have great signal processing powers, but only support 4 
> >> channels data recording. I have no idea about how easy it is to set 
> >> up on
> subject's
> >> scalp. Can people here with experience in EEG recording give me 
> >> some advises about what is the best product to pursue that fits my 
> >> needs? The following are my considerations:
> >>
> >>
> >> 1.       Good signal quality, which deserves the $10K cost
> >>
> >> 2.       More channels, the better
> >>
> >> 3.       Must be able to save data in my laptop, instead of subscribe
> and
> >> download from the manufacturer's web server
> >>
> >> 4.       Easy to set up, say within 10 minutes
> >>
> >> 5.       Portable to another country, ready for travel
> >>
> >> Any useful information will be greatly appreciated!
> >>
> >> Hong Lin
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