Music expresses creativity. Especially in electronic music, keyboards play a big role. However, keyboard interfaces consist of a rigid and heavy structure. Textiles are highly formable and palpable materials with a wide range of patterns, structures and textures, making them a suitable material for physical interfaces. Inspired by theremin's expressive controls (an electronic musical instrument controlled without physical contact by the performer) and the soft and deformable tactile properties of knitted textiles, the MIT Media Lab of Massachusetts Institute of Technology, Cambridge, MA/USA, has developed an interactive textile-based musical interface with a familiar layout of piano keys.
A keyboard made out of fabric, besides providing new interactions and tactile experiences for musical expressions, can be easily folded, rolled up, and packed in the luggage like a pair of socks or a scarf.
The prototype of the MIT Media Lab utilizes digital knitting technology and explores intarsia, interlock patterning, and a collection of functional (electrically-conductive and thermoplastic) and non-functional (polyester) fibers to develop a seamless and customized, 5-octave piano-patterned textile for expressive and virtuosic sonic interaction. The individual and combinations of keys could simultaneously sense touch, as well as continuous proximity, stretch, and pressure. The KnittedKeyboard II combines both discrete controls from the conventional keystrokes and expressive continuous controls from the non-contact theremin-inspired proximity sensors by waving and hovering on the air, as well as unique physical interactions enabled by the integrated fabric sensors (e.g. squeezing, pulling, stretching, and twisting). It enables performers to experience fabric-based multimodal embodied interaction and unique, intimate and organic tactile experience as they explore the seamless texture and materiality of the electronic textile.
The sensing mechanism is based on capacitive and piezo-resistive sensing. Every key acts as an electrode and is sequentially charged and discharged. This creates an electromagnetic field that can be disrupted by hand’s approach, enabling us to detect not only contact touch, but also non-contact proxemic gesture such as hovering or waving on the air, contact touch, as well as to calculate strike velocity. The piezo-resistive layers underneath can measure pressure and stretch exerted on the knitted keyboard.
This work brings the MIT Media Lab one step closer to the vision of seamless fabric-based interactive surfaces, that is not only applicable in novel musical controllers, but also in wearables, smart objects, and responsive environments. The underlining technology would enable further exploration of soft and malleable gestural interfaces that leverage the unique mechanical structures of the materials, as well as the intrinsic electrical properties of the knitted sensors.