Новини світу мікро- та наноелектроніки

This is probably pretty common since there are 8 (EIGHT!!!) of these inside a cheap Samsung monitor, still, found it really impressive that this is (1) possible & (2) economically viable.

hi hi again :3

Can't believe it took so long to get them, but I had to fix a few things here and there. Then I made an order during Chinese holidays, and customs, as always, requested a description for my PCBs but didn’t contact me, so I had no idea I had to do anything until the store called me and told me I’d better call DHL right now (please add me to the whitelist <3)

Description of the setup. For frequency testing, I was using a signal generator and scope together. Scope input signal point is the electrode test point, and output is the Vout test point. This way, whatever happens with the signal between the signal generator and the electrode itself does not matter. For the heartbeat signals, I had both passive and active electrodes connected in pairs (positive and negative): Bias was on my left leg (just one, passive as before, you do not need any active electrodes there), the first contact point is around the collarbone, the second contact point under my heart on the last rib. Passive electrodes are connected using sticky gel pads, active electrodes only dry contact with and without conductive rubber (1 mm thick, bought it on Adafruit store, if I measure resistance from top to bottom it gives me around 300 Ohm). To connect electrodes, I’ve soldered wire for the ground and 5 V output of my Meower board (link is right at the end). I thought I would add noise to the power rail and it would be bad — no, it’s fine :3

So, electrodes do work:

• Frequency response almost perfectly matches calculations (you can see it on the schematic pic)
• It looks like we can go rail to rail; it cuts the signal at 0 and keeps it alive until you hit above 5 V.
• I haven’t seen any problems with noise or clicks or any other types of noise I could spot in the time domain
• Dry contact use case with just direct contact gives not amazing but really good results — rattle noise, movements, network noise (50/60 and 100/120 Hz noise) almost nonexistent. The difference is huge. I didn’t even get what was going on at the beginning, thought something was wrong
• Dry contact with conductive rubber in between gives almost the same results as just direct contact, but I feel like it picks up a bit more electrode movement itself. Maybe I had to use adhesive between metal and rubber itself, but if it sits on your skin and the rubber has good contact with you and the electrode - almost no difference.
• There is a pic with heartbeat seignals. Green line is active electrodes and orange is passive. you can see there not only 50 and 100 Hz network noise, but also spikes - i was tapping on all cable at ones and the only one which pick up rattling were passive electrodes. So, rattle goes away, network noise goes down by alot even without filtering - looks really good.

So - now I can say - if you found this post, electrodes are tested and they do work. Schematic is correct (unless proven otherwise, if so let me know please :3). Conductive rubber works just fine, and I feel like just for normal use for BCI it’s the best way, so there are no contacts with any metal and it’s a bit softer and more comfortable. Thank you so much to everyone who told me I’m stupid and found problems here and there. I can’t believe I made 10 mistakes in 10 components, but I did :3. Though I’ve learned a lot. Anyway, thanks again.

You can find active electrodes files here
https://github.com/nikki-uwu/Meower/tree/master/hardware

- This chip incorporated 2 chips in one package. The CPU die and the L2 cache die.

- The chip also had a superscalar design and a RISC-based processor.

- The gold finishes are for bond reliability and corrosion-resistance. Plus, they look cool