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Wearables Inputs

Soft Switches

Switches are simple: two electrical conductors complete a circuit when in contact and break the circuit when separated. We can either sense the opening and closing of the switch circuit or use the switch to directly control parts of the circuit. Wearable switches use conductive fabric, conductive thread, beads, clasps, zippers, or other "soft" materials as the conductors.

References:

• Three Fabric Buttons on Instructables

Soft Touch Sensor I - Conductive Type

Another type of input for wearables is touch sensing. Though similar in construction to soft switches, touch sensors improve on switches in several ways. Like a soft switch, the first type of touch sensor has two conductors separated by air. Unlike a switch though, a conductive touch sensor operates when a user connects the two conductors with a finger or hand. Current flows through the user's body to complete the circuit.

The electronic circuit used is called a Darlington Pair. In a Darlington Pair, two transistors act as an amplifier, increasing the small amount of current transmitted through the skin to a usable amount.

References:

• Transistor circuits - includes a touch switch Darlington Pair circuit and explanation
• Touch sense circuit - Fritzing project and thumbnail

Soft Touch Sensor II - Capacitive Type

The second type of touch sensor, capacitive sensing circuits use measurable changes in capacitance between a probe and ground to detect a touch. QProx chips from are a popular way to add capacitive sensing to a project. A new library for Arduino requires just one resistor and allows the Arduino or Lilypad to sense touch.

References:

• Capacitive sensing library for Arduino (installation instructions and download link are near the bottom of the page)

Soft Force Sensor

Like a force sensing resistor, a soft force sensor has a resistance that changes with the amount of force applied. Use it as you would a regular FSR.

References:

• Conductive Thread Pressure Sensor on Instructables

Other Soft Inputs

Any type of input or sensor can usually, with a little modification, be built into a wearable. Bend sensors, photocells, and "hard" switches can be adapted. The Lilypad components are also worth a look; the lineup currently includes accelerometers, light sensors, and temperature sensors.

Compare and Contrast

Wearables Outputs

Light

LED Sequins

References:

• LED tank top by Leah Buechley - includes LED sequin instructions

Heat and Motion