EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Peter Gamma on September 14, 2020, 01:48:52 pm
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Scott Hardens sound card ECG can be used to feed in ECG sensor data through a computer microphone jack into a computer and from there to Scott Hardens software for data processing and visualizion.
https://www.youtube.com/watch?v=sP_-f5nsOEo&pbjreload=101 (https://www.youtube.com/watch?v=sP_-f5nsOEo&pbjreload=101)
Scott Harden has an instructional video how to soldier his device. It was developed for ECG, but according to Scott, it could also be used for other sensors like Piezoelectronic sensors, respiratory sensors, or EEG sensors. Scott Hardens device has the potential to be used instead of for instance an Adinstruments equipement with Labchart software.
I asked this question in the Matlab community. It was answered that it was unlikely to find there an answer, I should ask the question in Stackoverflow. There someone had a problem with it, he meant that it is not related to programming. Then someone found it would be spam, and a moderator deleted it. I protested. No it is hidden there, and some stated that the question is not in agreement with the term and conditions of the Stackoverflow. :palm:.
This circuit is great, and it could be revolutionary for test equipements. It is a low-cost Adinstruments channel recorder, which is very simple. A printed circuit board would make it easier to handle. And to reduce the size, would make it usable for EEG sensors on the scalp.
How can Scott Hardens Sound Card ECG circuit be printed on a circuit board to reduce soldering effort?
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Find or reverse engineer the schematic, do a PCB layout, go mass production, done?
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Already first solution there, this is the world champion blog, so fast.
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Will a Chinese manufacturer read this post and to the job for me? This device can compete with an Adinstruments channel recorder for 2000 USD. It is worth doing it.
I was lucky before by asking many questions. Bluetooth low energy sports sensors and new Garmin watches can now be connected to Matlab:
https://ch.mathworks.com/help/matlab/import_export/collect-data-from-fitness-monitoring-devices.html
Is this because of my endless effort to ask questions about this subject? Whatever. Thanks, MATLAB.
There is now also an EEG TGAM device available which can be connected over Bluetooth to Android, Windows or Ubuntu via BlueSoleil:
https://de.aliexpress.com/item/32606318948.html?spm=a2g0o.productlist.0.0.529214c9dFto0P&s=p&ad_pvid=20200913214957176422413807000004428579_1&algo_pvid=9f35bae7-c8c5-4490-a496-7ecc6070584b&algo_expid=9f35bae7-c8c5-4490-a496-7ecc6070584b-0&btsid=0ab6f83116000589967501667e9b62&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603
Has this something to do with my endless questions how to connect EEG sensors to a phone or a PC? Whatever. Thank you, Aliexpress.
I will buy from you, MATLAB and Aliexpress :-+.
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The schematic is on his website: https://swharden.com/wp/2019-03-15-sound-card-ecg-with-ad8232/
You don't need the op-amp buffer, unless you want a second output going to an oscilloscope.
You don't need the linear reg circuit, you can buy a 3.3V regulator module. Although that one is not exactly complicated to build.
The AD8232 module can be bought from sparkfun or elsewhere.
Maybe you can take some photos of the aliexpress unit when you receive it and post them here.
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I discussed the subject with Scott Harden on his Youtube channel. He developed the device and developed software for it, which is excellent and is under an MIT licence. Scott answered that he set this device free for anyone to develop it further. Therefore I m promoting the idea here. Yes, it would be great when this device could be bought somewhere.
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Scott Harden answers questions and supports his device and his software on his youtube channel:
https://swharden.com/blog/2019-03-15-sound-card-ecg-with-ad8232/
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One aspect of Scott software for the sound card ecg is really extraordinary: it can handle with multiple sound cards. It is possible to attach as many usb sound cards as you want to a PC, and control as many devices as you want with Scotts software. Normally Windows can only handle with one sound card at a time.
Also the ECG breakout board sensor can be replaced with EEG sensors, respiratory sensors, MEG, piezielectronic sensors, inductive sensors, etc. By combining several devices it becomes a similar device as an Adinstruments multi channel recorder.
With Bluetooth connections, as in the EEG device which is paired over Bluetooth, and can be connected to a phone or a PC, there is a problem with bandwith. An example for this is the EEG BLuetooth device which can be bought on Aliexpress which is mentioned above. It is not possible to bult up to many channels with Bluetooth devices.
With the Muse meditation headband for instance, which has four EEG channel, people reported that they had bandwith problems when they attached an additional Bluetooth headset to an Android phone next to the Muse headband.
With Scott Hardens sound card device, the number of devices which can run in parallel is not a limiting factor.
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Bitalino has similar products like Scott s sound card ECG:
https://plux.info/14-bitalino
and OpenBCI:
https://shop.openbci.com/collections/frontpage?utm_source=google&utm_medium=cpc&utm_campaign=716348300&utm_content=openbci&gclid=Cj0KCQjwqfz6BRD8ARIsAIXQCf0hzjgRqVURCPzJBaU-KXQv6P0AA59l6m1CBiKauYxb4ga2bN4dF88aAmkmEALw_wcB
I tried to find followers in both of these communites. Unfortunately, neither Bitalino nor OpenBCI seems to be open to new products. Scotts s device is easier than some of the Bitalino or OpenBCI products, and costs less. But the market for these products is small, and it is difficult to make money out of it. I thinks Scotts device has the biggest chances to be successful in the Open Source community, as many of these devices.
I can imagine that device will be picket up by Matlab users sooner or later, or someone is integrating it into a Python library.
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I ve bought several Adinstruments channel recorders on ebay. All of them where sold without software. It is possible to geht the Chart software from Adinstruments with the serial number of the device. But the chart software is a post processing software. Sound card ECG is real-time, and can fill this market segment.
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Matlab has the option of Matlab supported devices. Is the Sound Card ECG not in the range of other Matlab supported devices? I ask the question here, since the feedback in the Matlab community was negative as far as the sound card ecg is concerned.
When a device is accepted by Matlab, then they would also support the software. Is it not worth fighting?
I had similar problems in a similar case with Garmin and Matlab. In the Garmin forum, moderators caused me to leave the forum, deleted my posts and inactivated my Garmin forum account. In the Matlab community, one moderator threatened to delete all my posts which where not related to Matlab. Also in the case of the Garmin watch, is was a solitary fighter.
No, Matlab supports Under Armour chest strap Bluetooth low energy sensors, and Under Armour Bluetooth low energy running shoes. And also new Garmin watches which support BLE broadcasting :).
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I would say the design is unsafe as the electrode are directly connected to the patient and you would need to meet type BF earth leakage, 100uA under normal conditions and 500uA under fault conditions.
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How about safety with a setup which is completely battery powered? 220V or 110V devices need tests for safety. Do battery powered devices have to fullfill satety requirement?