W-3

The PCB shield has arrived! And after a quick rework, it works as expected!

There was an LED after the switch for indicating if it was receiving power. Turns out this was causing a voltage drop that resulted in a voltage too small to power the motors. This was measured and confirmed using an oscilloscope on test points for the motors (including test points was highly recommended by my mentor Kelli Noirot).

First oscilloscope reading. With the LED installed, the test points were only receiving 1.2V and the motors require at least 2V to work.

After reworking the PCB to remove the LED, the motors worked. The oscilloscope read exactly 3.3V which was the expected and desired voltage.

Now that the shield was working as expected, it was time to put it on a wrist.

Before doing anything, hot glue was added to where the motor leads attached to the PCB for strain relief. One motor was then tucked underneath the Trinket M0 and secured with kapton tape. Two pieces of velcro were stitched onto the Trinket as a basic strap. Once attached to a person’s wrist, the secondary motor was put underneath the strap on the inside of the wrist.

Findings:

• The vibration is definitely annoying

• Motors may be too strong. They currently make my whole hand vibrate.

  • Sound deadening will be needed if the motor intensity is not reduced.

• Too tall when the shield is mounted with header pins.

• First user test says that the intervals feel well-timed.

• Most settings do not replicate the feeling of true bilateral stimulation.

Feedback: My second mentor, Brandon Noirot, was the one to suggest that a voltage drop was possibly the problem. I was questioning if the vibration patterns were too quick and he said they felt like they were mostly well-paced.

Next week:

• Conduct the first round of user testing.

• Figure out where to put a battery.

• Make a slimmer version and begin CAD model for a case.

Mentors:

• Kelli Noirot

  • kelli.noirot@protonmail.com

  • Advisor for electronics, prototyping, and fabrication

• Brandon Noirot

  • brandon.noirot@protonmail.com

  • Advisor for electronics, 3D modeling, and fabrication.