5. E-textiles¶
I wanted to explore the how make simple sensors starting with bending, pressure, tilt
I didn't work with soft meterial and fabric in the context of electronics before. So first i wanted play with measuring the resistance of this meterials and see how do they reach to different interactions.
Here i did try the pressure sensor, to make a pressure sense you would need;
- Velostat — pressure-sensitive resistive sheet (sensing layer)
- Piece of fabric — for insulating (cotton, felt, or similar)
- Conductive fabric
- Multimeter or microcontroller with analog input — to read resistance/voltage
Prototypes¶
Pressure sensor¶
Voltage divider¶
To read a resistive fabric sensor with Arduino you must convert its resistance change to a measurable voltage using a voltage divider. Basic formula:
Vout = Vin * (Rsensor / (Rfixed + Rsensor))
Put the sensor in one leg (Rsensor) and a known resistor in the other (Rfixed). Choose Rfixed near the sensor’s nominal resistance so the voltage spans the largest portion of the input range as the sensor changes. Feed Vout to an analog input; analogRead() returns 0–1023 corresponding to 0–Vcc (usually 5 V or 3.3 V).
For a practical walkthrough and derivation see SparkFun’s tutorial
Bending sensor¶
Same principles also applies as in pressure sensor, you need to have range of resistance change and observe that change with multimeter. Arduino doesn't understand resistance, it speak voltage so you again to map that resistance change to voltage. For that you need voltage divider, which will map the resistance changes on the sensor to voltage ouput which arduino uses to measure changind analog value.
Graphite-on-paper based bending sensor¶
Didn't work, will try this again. I was expecting to decresing numbers on multimeter as you bend it, but it doesn't seem responding
