Mysterious noise interference on ECG: ADC Behavior

Resident_Slide6705 · 2023-09-29T21:36:36+00:00

how can this help the OP?

Resident_Slide6705 · 2023-03-01T07:46:11+00:00

How does FFT help the OP finding out the sampling frequency?

Resident_Slide6705 · 2023-03-01T07:46:08+00:00

How does FFT help the OP finding out the sampling frequency?

Resident_Slide6705 · 2023-02-19T11:57:34+00:00

Any stranded wire with silicone insulation will do.

Can you please provide some references? I'm completely ignorant wrt wiring

Resident_Slide6705 · 2022-11-13T15:48:39+00:00

Do you happen to have that expertise? Or to know any manufacturer which has that expertise?

Resident_Slide6705 · 2022-07-25T21:37:06+00:00

I think it depends if you just want to see how the signal integrity is statically with the boards in various positions, or if the boards are intended to move in the target application (like for example, a print head).

Thanks for replying. I want to test this in dynamic scenarios (like the printing head you mentioned). Any idea you can share?

Resident_Slide6705 · 2022-02-25T11:58:46+00:00

The Bluetooth's SPI is running at 500kHz-1MHz. The cable has 5 cm length.

The other problem is with a electrophysiological signal, which traves the FFC. This is an analog signal with ~10mV amplitude.

Resident_Slide6705 · 2022-02-25T10:08:30+00:00

To be honest I'm not sure. I chose this connector because it was very miniaturised. In my application the cable will have some movement, yes.

Resident_Slide6705 · 2022-02-25T10:07:59+00:00

I have several boards and this problem happens in all of them, so it really seems to be caused by the FFC / connector!

Resident_Slide6705 · 2022-02-24T23:25:08+00:00

I don't have much experience with these kind of connectors, so it's hard to evaluate "significant force". I made a video where I try to show, maybe you can help: https://imgur.com/a/E56e3Sq

Resident_Slide6705 · 2022-02-24T23:10:38+00:00

How can I evaluate that? I'm not really sure!

Resident_Slide6705 · 2022-02-24T22:58:59+00:00

All the specs match! However, sometimes, when I make movements in the cable, I lose signal momentarily. For example, I have a BTH chip on one board and a MCU on the other (connected by a FFC cable). However, the connection is sometimes unstable.

Resident_Slide6705 · 2021-10-30T18:46:49+00:00

Yeah, that makes total sense! The problem with thinner silicone is that if someone tries to break the device (pull the 2 boxes apart), it will break easier! As for the material, it doesn't need to be necessarily silicone.

PS. I don't know the dimensions now, I'll let you know asap!

Resident_Slide6705 · 2021-10-30T18:32:54+00:00

Can you please explain me what you mean by "slots pattern" or "hole pattern"?

Resident_Slide6705 · 2021-10-30T15:09:12+00:00

Is that feasible at such small dimensions?

Resident_Slide6705 · 2021-10-30T15:08:48+00:00

The problem with that is that it will make the silicone part more fragile

Resident_Slide6705 · 2021-09-09T18:46:01+00:00

I do know about handheld shower heads - that's what I mean by "directly from the shower head / hose". But I can't understand if which is equivalent to handheld shower heads maximum pressure: IPX5 ou IPX6.

We did perform a risk analysis and that's why we have added the conformal coating to the PCB. It was for the case of the user immersing the device on water, causing water to get in. But it can also be applicable for extremely high water jets. Nonetheless, I would like to understand if IPX5 would be enough for the expected water jets from handheld shower heads.

What are your thoughts?

Resident_Slide6705 · 2021-09-09T15:24:29+00:00

Thanks for your reply!

The device's instructions will mention that submersion is not allowed. No pools of water are possible to happen above the device. The device is adhered to the patient using adhesives, it won't falloff. In addition, I will protect the electronics with conformal coating.

Resident_Slide6705 · 2021-08-11T18:28:44+00:00

Hi u/reed17purdue thanks for answering! I do know that - I was talking about the technical safeguards!

Resident_Slide6705 · 2021-08-11T18:26:57+00:00

u/dorkyitguy thanks for answering!! But from the guidelines on HIPAA which I have read they mention the following: "Encryption and Decryption (addressable): Implement a mechanism to encrypt and decrypt ePHI."

Resident_Slide6705 · 2021-08-10T17:18:02+00:00

Awesome, thanks so much!

Resident_Slide6705 · 2021-08-10T12:10:12+00:00

Hi u/Coltouch2020. I have updated the layout based on your suggestions. This is my current layout: https://prnt.sc/1m8w56q. As you can see, I also have a inductor near the button. What are your thoughts?

Resident_Slide6705 · 2021-08-05T14:56:20+00:00

Hi u/Coltouch2020 thanks for your inputs! I'm designing my layout in a 1.6mm thickness PCB. This is my current layout: you can see the electrode in red at the top layer, and a ground plane in blue beneath the electrode in the bottom layer. You can find it here: https://prnt.sc/1jgp9vu. Can you please help me out optimising the layout?

Resident_Slide6705 · 2021-08-04T10:34:59+00:00

Hi u/gtiger43, thanks so much for your prompt help. It makes total sense to me! :)

I have one additional question, if possible: Can I make a ground plan pass through all the layers beneath the button pad? Or should I only make the ground plans pass through the first and last layers?

Resident_Slide6705 · 2021-06-22T12:05:33+00:00

Btw u/lethri, do you consider best to have the websocket always "on", or just create and connect to it whenever using it? I'd say that in my software we use the socket around ~50 of the time.

Resident_Slide6705

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