Cool study. 30 mins seemed a bit long but I was looking at US transducers and it would have to be very small to fit in the headset form factor to go against the tragus.

@Dana P I don't think so as the applicator head is too big and might be even too powerful for this tiny branch. We can still stimulate the vagus nerve lower down in the neck area.

Interesting. I wonder what they will say about it. I've been wondering about my Ultrasound applicator head material. The manual says its aluminium. I've only had mine a week, not used the warming feature, and have only used a wet microfibre cloth to clean it. There are already some very fine scratches which leads me to think it is aluminium.

I was using a Med-Fit 3 TENS for tVNS first with an ear clip and pad for ground, then the double ear clip electrode that goes either side tragus. It has been some time since I used the TENS, and I can say it was helpful for me, I just got out of the habit of doing it. I was using it a few times a week: approx 15 mins each time, 200μs PW, varying the frequency 15-30-20 Hz. I recently got a Med-Fit 1032 Ultrasound for PFC stimulation and discovered it could be used for vagus nerve, so I tried it out. I think it is better. I've been using it every day for 3-5 mins, and twice now it left me feeling calm with this expanded, grounded sense of awareness. Both have some downsides. The two TENS I own have analog control for intensity, and skin conductivity varied so I had to dial in intensity each time, being careful not to turn it up too high as that was so painful! Then there is that mild sound/sensation that was a bit annoying, along with my tragus sometimes feeling fatigued after use. The Ultrasound is quicker to use but as it's still new I'm very conscious of using it. I have long hair and the gel can get on it so I have to clean it off my neck/hair and applicator head afterwards. This device is larger and I think a little more fragile because of the ceramic transducer, so needs its padded case (which also holds gel and power adapter). I hear a tiny pulsing sound but I don't feel it, I only feel the coolness of the gel/applicator and I can move it slowly up/down my neck, which can be a little tiring because I am trying to position it carefully. If I had to choose which to take for a weekend, I would still bring the Ultrasound!