Outcome

Intention

From what I have learnt from Soft Fabrication course, I'd like to make a jacket correcting users' poor postures. Sedentary lifestyle and increasing use of computer accelerate this type of harmful behaviors which cause pain around neck and back. I have also experienced such pains offten as a design professional or a student.  

The jacket would give a haptic feedback(vibration) when a user leans forward more than a given threshhold. As the first step to achieve the project, I created some prototypes of bend sensors; the option 1 of the sketch below. 

Process

Finding Reference

To get some ideas, I visited www.kobakant.at/DIY and found several different bend sensors. Basically, the sensors* use Velostat, a semi-conductive material which become less electroresistive when it is applied mechanical strains like bending. For the sensors, it connects two conductive components to close a circuit as a switch does. I decided to use this method.

*Neoprene bend sensor, sheath bend sensor

Prototype 1

Two pieces of conductive thread are housed under the patch of Velostat seperately as the below image.  When it is bended, the electric resistance decrease so the two thread pieces are connected. 

** 3V coin-like battery was broken. Fortunately, I have an Arduino and breadboard...

• Sucesses : It worked well when it is bend!
• Problems : It worked even after the bending force was gone. I thought that this was because the thread almost directly contact with Velostat which might stay conductive after being bended.  

***I realized the fact that the circuit was wrongly wirely afterward. The problem was actually because of the wrong wiring.

Prototype 2

To address the problem of prototype 1, I provided some space between the thread and Velostat by making  an arch form with stitches as below.

• Sucesses : It worked well for either when it is bended and even when it goes back to the initial state.
  
• Problems : The led a little blinked. I assumed that the unstable connection was because the conductive thread stitches had small abount of contact area with Velostat.
  

Prototype 3

To enlarge the contact area, I replaced conductive thread with conductive fabric and widened the sensor. In this time, I also folded the piece of Velostat to make stronger arch.

YAY! It worked really well!

NEXT STEP!

1. Drawing a schematic including the sensor, vibrator, an arduio, and a battery.

2. Figure out the right threashold to notify users that they are in a poor posture.

3. Saw all of them on a jacket and test it out!

Sample Book