Pressure Sensor Boots

Experiment by: April De Zen and Veda Adnani

This week was an intro to pressure and stretch sensors. There were 2 techniques that we covered in class, the first was clipping fabric and fibres with alligator clips and extending the textile to create resistance. The second technique was to create a ‘sandwich’ textile tool to hold resistant materials that will allow more current to flow once pressure is added.

After class, Veda and I thought it would be cool to create sensors that go into a persons shoe. Here are the steps we went through to build this prototype.

Step 1: Understanding the Materials
(Tests with Multimeter and Arduino)


In class, we all received a bag of goodies, many pieces of fabric and fibre to show the resistance of a textile. So the testing began, we tested everything. We tested stretch fabrics, a grey cotton ball thingy and more black materials. Each material created resistance in different fashions so we began chatting about different opportunities that these affordances could be leveraged. Some materials offered quite a bit of resistance and others not so much, it was fascinating exploring the materials in this fashion.

Step 2: Sensor idea


Next came ideation, what kind of sensor should we create. Light up shoes are fun for all ages, and we wanted to try making a pair ourselves. We chatted through the placement of the sensor, should it be under the heel or under the toes? The interaction for a sensor under your toes would be different than a sensor under your heel. We step heel/toe, and quite a bit more of pressure is pushed through the heel. Since the sensor was going into a shoe, it made the most sense to use a pressure sensor rather than the stretch sensor. Off we went…

Step 3: Assembly


There is a process of making a pressure sensor, we need two pieces of non-conductive fabric that gives a bit of a squish feeling when pressed. Next, we needed two parts for conductive fabric, in this case, it was fabric tape. Then we need a material to go right in the middle which will act as a resistor, we used the velostat which was given to us for testing. Once all the pieces were cut out, it was time to sow it all together. We stitched the conductive fabric tape in place (since it was shifting around) and then some conductive thread was sown into the conductive fabric to extend the reach since this sensor is going into a shoe. Then we quickly sandwiched it all together and stitched up the sides making sure the velostat covered the conductive fabric completely. We didn’t want to current to skip over the resister we just created.


Step 4: Testing in Shoe


The sensors were now ready for testing. We quickly tested it outside of the shoe to make sure it would work. Since the main idea was to rThe sensors were now ready for testing. We quickly tested it outside of the shoe to make sure it would work. Since the main idea was to re-create a light up shoe, we went with using the e-textile tool with an LED for testing. It was fun testing this sensor out, the LED lite up as we stepped on the sensor. Once it was placed into the boot, we pulled the conductive thread through a few holes in the boot so we could connect the sensor again to the e-textile tool while we took turns walking.

Reflection and Learnings:
This was an enjoyable exercise. Now that this exercise is completed it easy to see the simplicity in what we created but it is also phenomenal that current can be altered through fabrics with a few simple tricks and understanding what each material can do for you. Besides taking Halloween costumes to a whole new level, we are both very excited to use sensors like this in upcoming projects.