Identifying and embracing opportunities for plurifunctional design is one of the most important practices to achieve sustainability. A component of a design can be said to be plurifunctional if a single material or assembly provides multiple functions concurrently. The term comes from the French philosopher of design and engineering, Gilbert Simondon. It is useful to have a separate term than multifunctional because most multi-tools (swiss army knife, multimeter) only make their functions accessible one at a time.
In e-textile work, designs that employ conductive thread usually exhibit plurifunctionality. Here is a list of some of the concurrent functions conductive thread can provide:
- Electrical conductivity
- Adhesion (binding together textiles)
- Sensing, e.g. interdigitated arrays
- Fiducial, e.g., tactile and visual indication of interaction site
Piezoresistive fabric can be used for
- Sensing, e.g., pressure, stretch
- Electrical conductivity
- Electrical resistance
- Actuation, e.g. heating
Plurifunctionality supports Sustainability Values by:
- Reducing the total number of elements and interfaces in a design
- Reducing exposure to supply problems
- Reducing the amount of development effort
It is valuable to critically examine current engineering and design practice with respect to plurifunctionality. A typical approach to design is to shop in huge catalogs of specialty parts and build functions additively by selecting parts, checking interfaces and developing custom shims and adapters to make the parts work together.
An example in the e-textile design space of this approach results in the Lilypad platform parts. The Lilypad microcontroller might be considered as the only plurifunctional part in the Lilypad ecosystem because many functions can be provided concurrently via software.
We are particularly inspired by the software available for the Teensy 3 series of micro controllers because it provides plurifunctional USB protocol support: mouse, keyboard, touchscreen, sound, serial connections, debugging – all available at the same time.