ThreadSense : Locating Touch on an Extremely Thin Interactive Thread

Motivation

Today's computing technologies are "weaving themselves into the fabric of everyday life", as Mark Weiser envisioned 28 years ago. Innovations in materials, sensors, and soft electronics are quickly changing the way people interact with computers and what people are interacting with. Touch input, for example, has gone from the rigid body devices like touch screens and found its way in one-dimensional (1D) soft sensors (e.g., stripe, cords) that can bring interactivities to everyday objects such as drawstrings and headphone wires.

In this paper, we introduce a new approach for locating up to two concurrent finger touches on a thin thread made of conductive material using the principle of impedance sensing. This approach works on cords, stripes, and more importantly, very thin threads (less than 0.4 mm thick) with a simple structure (a single line of resistive material) that cannot be supported by existing methods using pressure, capacitance, or time domain reflectometry. Thus, our new approach extends touch input to everyday thin threads, such as tinsels, braids, wire crafts, or embroidery.

ThreadSense prototype in (a) a thin thread of less than 0.4 mm thick. Our sensing technique can locate up to two finger touches on extremely thin objects, found in (b) braided hair band, (c) embroidery, and (d) wire craft.

Demo Applications

Interactive Hair. We implemented our sensing technique on a braided headband to allow gestural input to be carried out as if the user is touching or scratching the hair. Although touch input on the hair has been explored in prior research, the state-of-the-art methods can only sense the occurrence of touch. With ThreadSense, the systems can also detect swipe gestures for an extended input vocabulary. The use case for this type of input is broad. In particular, we see its benefit of being less obtrusive in social settings. For example, in the situations where repeated interacting with a smartphone or watch (e.g., checking voicemail messages) can be considered inappropriate. Swiping the hairband is less interruptive to other people since the motion is ambiguous about whether the user is actively using technology or just touching the head. In our implementation, a single touch on the sensor hangs up the phone call, and a swiping gesture changes the phone to mute mode. Although there is only one thread sensor in our current implementation, we foresee that the entire headband can be augmented with our sensing technique in the future with more research efforts. This will enable a much richer set of interactions via the hair.

Interactive Embroidery. The next application is an interactive embroidery that allows the user to perform input on a soft object covered or made by interactive fabrics. In our implementation, we manually sewed our thread sensor onto an owl embroidered cushion cover. Touching different locations on the thread triggers different actions on a smart IoT device. For example, touching somewhere near the first owl disables/enables the microphone of the Alexa. Tapping near the second owl using one finger turn on the music. Tapping near the same location using two fingers plays news. Swiping near the same location navigates the menu. This way, the cushion becomes the user’s always-available remote controller at the couch and can be used when voice input is not desirable.

Interactive Wire Crafts. Another example of bringing rich interactivity to objects that are traditionally passive is through wire crafts. In our third application, we developed an interactive tulip bookmark. When in use, the bookmark has a new function that allows the user to perform continues touch input to control the brightness of the ambient light while reading. For example, the user can slide the finger to increase or decrease the brightness of a lamp.

Selected Press Coverage

Hackster.io: ThreadSense Brings Touch Sensing to Interactive Thread