Re: [Openeeg-list] Make your own Pulse Oximeter with a couple of LEDs

[Biotele <ee...@bi...>]

Hi Marx,

 

DOT is slightly different pulse oxymetry. This is a fantastic presentation
on DOT:

 

http://www.martinos.org/martinos/research/MultimediaGallery/DOT_materials/do
t.html

 

 

 

From: Phillip Marx [mailto:phi...@sb...] 
Sent: Tuesday, February 24, 2009 5:02 AM
To: Discussion of EEG hardware, software, training protocols, NFB theory -
for developers and users.
Subject: Re: [Openeeg-list] Make your own Pulse Oximeter with a couple of
LEDs

 

http://www.edn.com/article/CA6607193.html?text=bonnie+baker

 

 

http://www.google.com/search?hl=en
<http://www.google.com/search?hl=en&q=Transimpedance-amplifier+application%3
A+The+pulse+oximeter+&btnG=Google+Search>
&q=Transimpedance-amplifier+application%3A+The+pulse+oximeter+&btnG=Google+S
earch

----- Original Message ----- 

From: Biotele <mailto:ee...@bi...>  

To: 'Discussion of EEG hardware, <mailto:ope...@li...>
software, training protocols,NFB theory - for developers and users.' 

Sent: Tuesday, February 24, 2009 2:13 AM

Subject: Re: [Openeeg-list] DOT, HEG & TMS

 

This is so awesome. Thanks Stefan.

 

From: Stefan Jung [mailto:bio...@gm...] 
Sent: Tuesday, February 24, 2009 1:04 AM
To: ope...@li...
Subject: [Openeeg-list] DOT, HEG & TMS

 

Hi All

 

DOT = Diffused Optical Tomography.  Those that are interested in this
subject can download a 2004 PhD thesis by Andrew Siegel here:
<http://nmr.mgh.harvard.edu/PMI/PDF/siegel-diss>
http://nmr.mgh.harvard.edu/PMI/PDF/siegel-diss  - Chapter 4 is the most
interesting, but the technology discussed there is rather old-fashioned,
using TTL glue logic, etc.  This could be done much neater with a modern
processor or FPGA.  

 

There is a Yahoo group by the name of deepHEG that has been created for the
purposes of developing such a device.  I have joint this group but it seems
still-born.  My membership to deepHEG is still pending after many weeks. . .

 

I personally am more interested in the more affordable/practical technology
of HEG = HemoEncephaloGraphy which besides EEG, is the only other
"practical" method of doing neurofeedback.  The pre-frontal cortex is a very
important area of the brain where a lot of problems originate, that could do
with NFB treatments.  Problem is, this area is very difficult for EEG due to
the EOG eye movement artifacts and the EMG/ sEMG artifacts due to facial
muscle activation.  That is why HEG is so in demand, it does not suffer from
these electrically based artifacts.  HEG is also a no-brainer ito protocol
design/training, etc.

 

There are two types of HEG.  Passive InfraRed - pirHEG (invented by Jeff
Carmen).  This is basically a non-contact IR thermometer that measures small
changes in forehead temperatures.  These devices use a thermopile sensor.  I
have designed & build my own prototype of such a device but I am struggling
to get it to work meaningfully.  It resolves temperatures down to 0.01 deg C
(Jeff's device can apparently resolve down to 0.01 deg F) but even with
proper ambient temperature correction look-up tables implemented, I still
have issues with temperature drift.  The data is send via usb to BioExplorer
where a temperature up-training protocol is usually implemented.

 

The second type of HEG is Near InfraRed HEG - nirHEG (invented by Hershel
Toomim).  This is patented technology and is basically a SpO2 meter also
known as a pulse-oximeter as used in hospitals for at least 25 years.  I am
in possession of a number of circuit diagrams of commercial SpO2 meters and
these things are rather complex.  The reason for the complexity is due to
the accuracy, low drift, etc. requirement of the target application.  For
HEG purposes, one only needs relative measurements.  But I believe that the
***resolution*** requirement for nirHEG too, is much higher, so this will be
a challange in itself.  Texas Instruments has an application note for a
single-chip SpO2 meter.  It is based on a MSP430 micro.  I was thinking of
building and testing that device to see if one could use it for HEG
applications. . .  but I don't seem to find the time.

 

With regards to TMS, the best known comercial device is the Shakti Helmet
also refered to the "God helmet" due to the work of Michael Persinger and
the claim that wearing such helmet induces religious experiences.  But one
should look past this "religious" claim; there are serious applications for
TMS as well.

 

Stefan

 

 

 

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