The KnittedKeyboard prototype was created by using advanced 3D knitting machines. By using this technology, the customized keyboard could be printed in just one hour. (Image Credit: Andreas Eggenberger, MIT Media Lab)


Instruments aren’t flexible or stretchable, but advanced 3D knitting technology could change that. Researchers at MIT’s Media Lab have developed KnittedKeyboard, a textile-based interactive surface created via machine knitting technology. This music controller is capable of responding to discrete touch, proximity, electric fields, pressure, stretch and slides.  In the future, this technology could be used in a wide range of applications, including health monitoring and therapeutics, rehabilitation, and sport science to architecture and space.


Today’s knitting machines are optimized to mass-manufacture garments and technical fabric. Digital fabrication and computer-aided design have altered 3D knitting with computerized (CNC) knitting machines. By using these machines, users are able to customize and create their own textile patterns via a specialized visual programming environment and different types of yarn. Researchers used this technology to create the KnittedKeyboard in just one hour instead of several weeks.


The team’s design uses intarsia, pocket patterning, and an assortment of yarns to create a piano-pattern textile for both expressive and virtuosic sonic interaction. To create the KnittedKeyboard prototype with its physical properties and responsive sensing and display capabilities, the researchers combined functional yarns (conductive, thermochromic, and composite) with non-functional yarns (spandex and high-flex polyester).


This illustration shows how the keyboard responds to touches or proximity, changing its display colors. (Image Credit: Irmandy Wicaksono, MIT Media Lab)


KnittedKeyboard consists of two different mechanisms: sensing and color-changing display. The sensing mechanism is based on capacitive and piezoresistive sensing technology. Each key behaves as an electrode and is charged and discharged, causing it to generate an electromagnetic field, which can be activated when a hand either touches or comes in close proximity with it. This also allows it to detect hand gestures, such as waving or hovering, contact touch, and it can calculate velocity. The piezoresistive layer beneath the fabric is capable of measuring the force applied on the keyboard. Researchers mapped the pressure value as an aftertouch modulation after a specific delay.


Meanwhile, the color-changing display mechanism characterizes the two modes of play: contact and non-contact. A central processor then transforms the sensor data to the musical instrument digital interface (MIDI) messages. Afterwards, the messages are sent to a computer via USB. Ableton Live and Max/MSP audio sequencing and generation software were then used to map the MIDI messages to their respective channels, controls, and notes.


This keyboard builds on the first iteration, FabricKeyboard, and exhibits a new fabrication process of fabric-based interactive surfaces. KnittedKeyboard can be accessed by musical artists, allowing them to experience multi-modal interaction while exploring the electronic textile material.


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