Some questions regarding the Free Style option, BLE and iOS

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Dank
Posts: 2
Joined: Fri Aug 22, 2014 3:23 pm

Some questions regarding the Free Style option, BLE and iOS

Postby Dank » Fri Aug 22, 2014 3:39 pm

Hello all!

Glad I found your great hardware ;) I want to develop a t-shirt prototype that can stream heart-rate data via BLE to an iOS device. I tried to read as much info as possible from the main website, but I still have some doubts. I will itemize for simplicity's sake:

1) How simple is it to use the ECG sensor in a t-shirt? Do I have to gel them every time I need to use it? (They will be "sewed" onto a textil, so constant replacement and/or gelling is not a neat option...). I also read a topic here stating that the skin should be cleaned with alcohol and hairless...does it really have to be like that? The readings would be done during wearer's exercising...
2) Since I need to, among other things, stream in real time via BLE, can I hook up the ECG module to an RFDuino? (I am guessing the ECG module converts the sensed raw data into actual meaningful BPM values...)

That is all for now.
Looking forward for your reply!

EDIT: Found the topic and was not happy about it :( viewtopic.php?f=3&t=135&p=251&hilit=placement#p251
"Regarding the use of the electrodes, they are disposable and may be used only once. The skin should be cleaned with alcohol before the placement and also should be safeguarded that the skin is dry. It is also good to ensure that there is an area without any hairiness"
That is not good for my sweaty scenario where the electrodes are placed on a t-shirt... What is the common error rate associated with this scenario? Can you provide any info about it?
Cheers.
Last edited by Dank on Fri Aug 22, 2014 5:51 pm, edited 1 time in total.

BITalino
Site Admin
Posts: 567
Joined: Tue Aug 27, 2013 3:47 pm

Re: Some questions regarding the Free Style option, BLE and

Postby BITalino » Fri Aug 22, 2014 5:18 pm

Hi there,

First of all we'd like to thank you for the positive feedback and interest in BITalino. Regarding your questions:

1) It should be fairly easy; the gel, alcohol, hair shaving, and all that is more for fine-grade medical application. With a bit of tinkering to check the placement of the sensors that provides the best performance, you can either use our non-gelled electrodes or (perhaps even better) the conductive textile electrodes; a slim fit t-shirt is recommended to have good :
http://store.bitalino.com/index.php/standard-account-store#!/~/product/category=9071126&id=35652024
http://store.bitalino.com/index.php/standard-account-store#!/~/product/category=9071126&id=35652031

2) You should definitely be able to easily hook up the sensor to one of the analog inputs on the RFDuino; the supply voltage of RFDuino is even compatible with the sensor, you just need to take care of creating the midpoint voltage with a resistive divider (http://forum.bitalino.com/viewtopic.php?f=12&t=14#p149), but the sensor board is even preset for that to be done easily.

Note that the ECG sensor provides raw data (http://forum.bitalino.com/viewtopic.php?f=12&t=14#p157); the heart rate is then computed from that data.

I hope you found this information useful. Do feel free to contact us for any further information you may need.

Best regards,
The BITalino Team


Dank wrote:Hello all!

Glad I found your great hardware ;) I want to develop a t-shirt prototype that can stream heart-rate data via BLE to an iOS device. I tried to read as much info as possible from the main website, but I still have some doubts. I will itemize for simplicity's sake:

1) How simple is it to use the ECG sensor in a t-shirt? Do I have to gel them every time I need to use it? (They will be "sewed" onto a textil, so constant replacement and/or gelling is not a neat option...). I also read a topic here stating that the skin should be cleaned with alcohol and hairless...does it really have to be like that? The readings would be done during wearer's exercising...
2) Since I need to, among other things, stream in real time via BLE, can I hook up the ECG module to an RFDuino? (I am guessing the ECG module converts the sensed raw data into actual meaningful BPM values...)

That is all for now.
Looking forward for your reply!

Cheers.

Dank
Posts: 2
Joined: Fri Aug 22, 2014 3:23 pm

Re: Some questions regarding the Free Style option, BLE and

Postby Dank » Fri Aug 22, 2014 6:09 pm

Thanks a lot for the quick reply!

I didn't quite get the non-gelled electrodes and the conductive textile electrodes. If I understood correctly, I can use the Conductive Lycra Fabric to work as a textile of the t-shirt...then, I would just need the 3-lead pads to touch that textile. Right? In other words, the Conductive Lycra Fabric would work as a middle layer between the skin and the pads...right? I am sorry, but I've never worked with body signals before...

About the ECG raw data... I assumed your MCU took care of that data to compute the heart rate. If I want to send it via BLE, I would then have to compute it in the RFDuino...
IF your MCU does compute that data into HR, I could also then use a simple BLE module like Printoo's (http://www.ynvisible.com/printoo/shop/#pack)


Just one more thing: since this is to be used when the wearer is exercising, what is the common error rate when in contact with sweaty non-hairless skin? Any info on that?

Thank you very much for all the help! I just need to know if it theoretically fulfills my requirements before placing the order :)

Cheers!

BITalino
Site Admin
Posts: 567
Joined: Tue Aug 27, 2013 3:47 pm

Re: Some questions regarding the Free Style option, BLE and

Postby BITalino » Mon Sep 08, 2014 10:33 am

Hi,

Please accept our apologies for this late reply, but we had the vacation season in the meanwhile and only came across your post today. For the Conductive Lycra Fabric you need 3 strips to be applied to the shirt; these strips will replace the pads (the fabric is shipped with studs for that purpose).

Regarding the heart rate, our MCU only does raw data streaming... the firmware available online (https://github.com/BITalinoWorld/firmware-bitalino), which means you can change it to compute the heart rate and reprogram the MCU. Another alternative is indeed to compute the heart rate on the RFDuino.

For the time being we don't have information on error rate on sweaty or hairy skin. Sweat actually helps in getting better signal quality, hairy skin shouldn't be a problem with gelled electrodes but the fabric may be more sensitive.

Note that you can also choose a placement for the electrodes on the shirt for which the area underlying the electrodes is less prone to body hair, namely the shoulders and hip/belly side (e.g. http://forum.bitalino.com/download/file.php?id=49).

Best regards,
The BITalino Team

Dank wrote:Thanks a lot for the quick reply!

I didn't quite get the non-gelled electrodes and the conductive textile electrodes. If I understood correctly, I can use the Conductive Lycra Fabric to work as a textile of the t-shirt...then, I would just need the 3-lead pads to touch that textile. Right? In other words, the Conductive Lycra Fabric would work as a middle layer between the skin and the pads...right? I am sorry, but I've never worked with body signals before...

About the ECG raw data... I assumed your MCU took care of that data to compute the heart rate. If I want to send it via BLE, I would then have to compute it in the RFDuino...
IF your MCU does compute that data into HR, I could also then use a simple BLE module like Printoo's (http://www.ynvisible.com/printoo/shop/#pack)


Just one more thing: since this is to be used when the wearer is exercising, what is the common error rate when in contact with sweaty non-hairless skin? Any info on that?

Thank you very much for all the help! I just need to know if it theoretically fulfills my requirements before placing the order :)

Cheers!


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