We have discussed this topic previously:
We have now a large number of demo devices with the ADS1299 chip. But not a single one of those (exept for openbci products, smarting mobi, mbraintrain) have delivered a convicing proof of function by independent testers that these demo devices work and are more than abandonned prototypes with noisy EEG signals:
And the devices which are on the market are not open source and expensive. We have no open source platform with more than 16 channels which was a success and is on the market. The only option is to build it by ourselves. After studying such devices based on the ADS1299 for several years, we came to the conclusion that building EEG devices with more than 16 channels is not too difficult. But it has do be done carefully and the features of the ADS1299 have to be understood. Should we choose daisy chain or an external clock to get more than 16 channels? At least two devices, those from Indonesia and the BEATS from China with 32 channels use daisy chain.
Devices should be tested also by independend testers. That is what we currently miss with the available devices. Not even a hardware platform his there which has a proof to be free from noise in a convincing way. A small single board computer or microcontroller such as the Rasbperry Pi Pi RP2040 combined with the the ADS1299 would be a good starting point, since the Pi RP2040 draws only little power. As mentioned before, we could start by soldering a Pi RP2040 to PiEEG, or even simpler, to test the available Pi models such as the Raspberry Pi zero if it works without noise with PiEEG. But unfortunately PiEEG has not yet a community who would test PiEEG. PiEEG has been delayed for a year. ADS1299 products are sometimes offered with intransparent conditions and many unclearities. And we do not have a community for these devices, but rather a lot of demo devices no one seems to use.