The US FDA has approved the Smart Skin product from Israel’s X-trodes (see here previously). The patches have embedded electrodes and can be attached anywhere on the body, to measure brain activity (EEG), heart activity (EKG), eye movements, muscular activity, and other signs.

https://en.globes.co.il/en/article-fda-approves-x-trodes-monitoring-patch-1001472240