It is proven that tactile stimulation can cause entrainment in the brain. Years ago I a recall a device in the form of a yoga mat that could be set to give tactile stimulation for various brainwave frequencies. I don't think it took off very well (it was pretty expensive), as I don't see it available anymore. I did find this device

I have also experimented with a TENS unit, but I have not found a device where you can dial in specific pulse frequencies.

I think having such a device would be a benefit especially for students wishing to sharpen their focus in classroom or lecture settings, and possibly to help calm individuals with social anxiety or to calm you down when making a speech.

Anybody have any experience with this type of stimulation for entrainment, or have any info on devices using this method?