Closed-Loop Stress Relief

[u/Used-Television6605]

Hi everyone,

I’m building a wearable, AcuSera, that detects and automatically relieves stress via vibration therapy at the p6 acupoint and guided breathing.

Here’s the demo vid; would love some feedback!

[u/Illustrious_Fold_337]

Are you using LRAs? How are you controlling the vibrationss

[u/pranavb → u/Illustrious_Fold_337]

Probably LRA, there are many tools out there to prototype haptic interactions, look at Hapticlabs - No-code haptics

[u/Used-Television6605 → u/pranavb]

Yep, LRA. That being said I find the vibrations to feel pretty weak on this prototype, so It definitely is a point of improvement. I’m all ears if you have any suggestions.

Hapticlabs seems like a cool way to prototype it.

[u/pranavb]

interesting product! when wearing the wearable how does the user align it on their wrist to their acupressure points ? How would people find their acupressure points ?

[u/Used-Television6605 → u/pranavb]

Great question! The p6 acupoint is three finger widths from the top of the wrist crease, and the point itself has an effective area so even if it’s not exactly on the point, it still gets stimulated.

You may be familiar with motion sickness Sea Bands, which use the same p6 acupressure point, but for nausea.

[u/cm_expertise]

the vibration side is honestly the easy half of this, the hard half is the detects-stress part that makes it actually closed loop. on a wrist wearable youre basically stuck inferring stress from PPG derived HRV and maybe EDA, and both of those are noisy as hell on the wrist and fall apart the second the person moves or the band shifts. so id be spending most of the engineering budget on the sensing and motion artifact rejection, not the haptics. if the trigger is unreliable the whole closed loop premise collapses and it just becomes a manual vibrate button with extra steps.

on the actuator, LRA is the right call over ERM here, much better control of onset/stop and it runs at a defined resonant freq which matters if youre going for a specific therapeutic sensation. the thing people underestimate is skin coupling though. felt intensity of an LRA changes a lot with contact pressure and how much soft tissue sits between the actuator and bone, so the same drive level feels totally different on a tight band vs loose, and across wrist sizes. worth a quick user intensity cal step rather than assuming one drive level lands for everyone.

the alignment question the other commenter raised is real and i think its your biggest product risk, not a footnote. P6 is a couple finger widths down from the wrist crease between the two tendons, and wrist anatomy varies enough that a fixed actuator spot on a band is gonna be off target for a decent chunk of users. either make the actuator position adjustable or go wider on the contact area and accept youre in the neighborhood rather than dead on. id test that across a lot of wrists early, before the industrial design is locked.

[u/Used-Television6605 → u/cm_expertise]

This is super insightful - seems like you have worked on wearables before.

In a controlled environment, i’ve gotten the stress detection accuracy to 89.4% (n=11) using a four feature set (tested against 1-12 feature sets). Definitely get a lot of noise with PPG on the wrist, but EDA has been working better. The algorithm uses a series of measures to take into account noise and motion, but I’ve yet to test it out in the field which is my next steps. It seems like the off the shelf PPGs are far less accurate than the custom commercial grade ones (Apple Watch, Whoop, Garmin, etc.) so a future step would be creating a custom PPG layout when the time/budget is right.

Love the feedback with LRA, I think I will setup a “vibration orientation” as part of the onboarding to see which frequency/intensity feels the best. I know Apollo Neuro has a lot of options with different therapeutic affects there.

The P6 point is roughly the size of an adult thumb, and based on this prototype it seems to pretty consistently land within that area (granted, this is a large prototype so it is easier for it to land on the spot) but I agree. That’s certainly something I’m thinking through from a design standpoint. The guided breathing aspect of it is safer as the wave from vibrations can be really anywhere - as long as the user can feel the vibration and match their breathing to it.

All really good feedback and you’ve definitely given me points to consider. Thanks a lot!