Temp & Humidity - Nylon/Spandex Fabric

What does the sensor do?

Temperature & humidity sensing.

How it works?

When temperature increases, the possibility of thermally activated electrons "jumping" across the potential barrier between carbon black particles on the fabric will increase, leading to lower resistance. On the other hand, when exposed to high-humidity environments, fabric fibers will absorb water molecules and swell, increasing the distance between carbon black particles and resistance.

Notably, the piezoresistive effect can still exist in the electrode connection areas. To reduce this effect, the fabric to be coated with carbon black should be thin (e.g., 0.3mm single-layered nylon spandex fabrics), and the resistance of conductive fabric should be relatively large (empirically at least 500kΩ) by incorporating serpentine shapes. As a result, the resistance change caused by the piezoresistive effect will be insignificant compared to the change caused by temperature or humidity.

You will need:

• carbon black ink and polyurethane
• nylon spandex fabrics
• conductive silver fabric

Sensor structure & Fabrication steps

• Laser cut nylon spandex fabrics incorporating serpentine shapes.
• Dip-coat the fabric.
• Connect with silver fabric segments.

Application scenarios

Suitable for temperature or/and humidity sensing purposes. See wearable sensor patch for pressure ulcer prevention.