Zoe Romano from OpenWear.org just wrote a nice blog post about the SUPSI workshop and published the laser cut felt module which provided the base for the #BalanceShirt prototype under a CC-BY-SA license. Thanks!
Just found PostureTek, a commercial product
designed to correct improper posture. The PostureTek system is a revolutionary, yet simple-to-use posture aid that uses biofeedback technology to sense incorrect posture. It trains the body to maintain correct posture at all times, and can be worn all day long—whether at the gym, at work or at home. It’s a safe, comfortable and easy to use posture aid that can benefit anyone, from young adults to seniors.
The biofeedback training system is housed in a small microfilament cable incorporated into the PostureTek clothing, running throughout the upper back and shoulder area. These microfilaments sense changes in the cable tensions whenever posture has been compromised. Instantly, a tiny, silent vibration is sent to the Activation Disc situated under the left armpit, alerting you (and only you) to restore proper posture. Once you have, the vibration will stop.
Not exactly the same, but gives a good hint at where to place the vibrators.
Unfortunately (from a design and wearability perspective) the only way to make this setup work in time for the SUPSI presentation was adding wires to lower the resistance of the critical connections. Troy, who also attended the workshop and is a wearable electronics expert, later told me that he too is using wires in many of his own designs. For a later revision it might also make sense to sew on additional traces of thread, as suggested by Massimo during the project presentation.
With LEDs only, the acceleration sensor and everything else worked fine. But as soon as the vibrators were attached, the setup stopped working. After measuring the voltage drop over some connections with a multi-meter it was clear that the vibrators did not get enough current / voltage. This seems to be a consequence of the rather high resistance of conductive thread.
Clipping on some wires confirmed this. With the wires on the bug was fixed.