Hi I'm Maas
Hi I'm Abel
We are presenting FabriClick, Interweaving Push Buttons into Fabrics Using 3D Printing and Digital Embroidery
This pictorial presents a new way to fabricate and enable eyes-free inputs on wearable e-textiles by integrating tactile pushbuttons into fabrics, seamlessly
On-body and wearable user interfaces boosted the availability of human-computer interaction
Their subtlety and closeness to the skin enable eyes-free inputs and social acceptance
However, tactile push buttons, which have been providing physical landmarks and tactile feedback for blind typing for decades
were often opted out from their considerations because its physical mechanism is not so compatible with the soft wearables
We explored the possibilities of integrating tactile pushbuttons into the fabrics with 3D printing and digital embroidery
With 3D printing, we embedded structures into stretchable fabrics that utilized spring tension to create 2.5D morphing shapes
The result of exploration is the design of a star-shaped button which provides the most desirable tactile button behavior
Once we achieved the desired button behavior, we needed a way to register inputs and make the buttons work
We 3D printed the tactile interface architecture, and digitally embroidered the electronic circuits to record and transmit inputs
In order to utilize the strengths of each method, we had to seamlessly combine the two without losing precision
We developed a frame system that augmented both machine workspaces to make this possible
After a one time calibration, our frame system can interchangeably print and embroider onto the fabric without interference
To create the buttons, we embroider and 3D print on two separate layers later joining them with embroidery to create a combined e-textile
Finally, we remove it from the frame and interface the buttons with a microcontroller.
As a result, the tactile push buttons become an eyes-free wearable interface
providing 3D physical landmarks and clear haptic feedback when the wearer is using it
HCI and e-textile researchers have been able to measure user inputs such as touch and gestures
through capacitive, resistive, or inductive sensing by utilising sewing, weaving, braiding, and digital embroidery techniques
However, the haptic feedback is often missing
This lack of clear haptic feedback and error-free haptic feedforward
can limit the user experiences of these tactile sensors in eyes-free wearable applications
This pushed us to research tactility in wearable pushbuttons which primitively supports eyes-free inputs such as typing
In addition to the physical landmarks of a pushbutton, the passive haptic feedback, such as the tick during the press of a pushbutton
can help users confidently confirm their eyes-free inputs
Wearable researchers have utilized the haptics from conventional electronic modules and customized controllers
such as springs and tines to provide recognizable haptic feedback
However, these are often made using non-fabric materials attached to or sandwiched between fabric layers
reducing the flexibility, stretchability, and softness of the textile
As we developed the pushbutton structures we had to be conscious of ensuring functionality
without sacrificing wearability through unnatural or excessive rigidity
We explored methods to fabricate 3D pushbuttons that provide both structural integrity and flexibility for the inputs
We used TPU to 3D print star-like patterns on the pre-stretched Lycra fabric
This results in button structures that restrict fabric movement in printed areas, enabling programmable behavior of button depth and strength
The tension of the Lycra fabric is then used as the driving force
and the printed button will provide the structural integrity enabling the tactile feedback
Through abstraction and exploration, we pursued developing a textile-based sensing method that could functionally register presses
Therefore, we chose digital embroidery, using conductive yarns and zig-zag stitches to ensure flexibility and durability in measuring button presses
To ensure reliable sensing, we adopted the principles behind a button matrix circuit
Using parallel tracks of conductive yarn and attaching conductive copper pads underneath each printed button, we formed an array of physical switches to register and transmit button presses.
The next challenge is to seamlessly integrate the workflow of the 3D printer and the embroidery machine
Numerous projects have augmented 3D printers with robotic arms to achieve higher degrees of freedom while others took a modular approach
using attachments to leverage existing hardware to achieve new machine capabilities
In this work, we unify the workflow of the two fabrication methods by augmenting the fabrication machines using a customized frame system
The frame system consists of four layers: The Baseplate, The 3D printing frame, The Embroidery frame, And the inner support plate
The baseplate is installed and calibrated onto the print bed of the 3D printer
Calibration is done by embroidering a cross on a piece of lycra fabric, after which we insert it into the baseplate and print over the embroidered cross
We position the baseplate so that the virtual centers of the two machine workspaces line up exactly
Calibration forces the automatic alignment of all frames placed onto the baseplate
The 3D printing and embroidery frames are made for aligning the respective patterns
The inner support plate snaps into the central frame cavity, allowing physical support during the 3D printing to enable proper fabric adhesion
Now let’s walk through how we fabricate a FabriClick button interface
We begin by pre-stretching and securing the fabrics onto each frame, ensuring they are in a high tension state throughout the entire process
Next, we begin the 3D printing process. The 3D printing frame snaps into the baseplate, aligning it into place, so that we can print the star-shaped button structures onto the top layer fabric
Once printed, we attach conductive copper pads to the underside of the 3D printed layer
Now we move to the embroidery frame. Using HC 40 highly conductive thread, we embroider a network of tracks onto the bottom layer, creating an open switch at each button location
Once both layers are processed, we align and combine the two frames to unify the two layers using embroidery
Finally, we crimp coated-copper wires onto the individual embroidered track outputs allowing us to easily bunch and run the wires to the processor
With this fabrication method, we explored several design parameters like the length of button legs, the number of button legs, the depth of press
and then identified the optimal design, which is a button in a 3D tapered structure
We’ve tested the haptic feedback with a formal force-displacement measurement and the durability through cycle testing by pressing each button 4000 times
The results showed that after 4000 times of pressing, the haptic feedback is still clearly observable in each button
The button’s electrical connection was still functional showing the matrix’s durability during extended use
We also explored the wearability by deploying the buttons at various body locations in an informal embodied ideation session with five subjects
Overall, the participants recognize and appreciate the haptic feedback of the textile pushbuttons, and think the samples are soft and comfortable to wear
From their experiences, we learned that button arrays placed at the location of soft parts such as the upper arm, or moving parts such as the elbow joints, were not completely reliable
This problem could be mitigated if the sleeve fits the wearer’s body tightly
We see these buttons in future wearables with a broad range of application areas
They can be used in health applications where highly flexible, durable wearable controls are needed
Gaming applications, such as in VR on-body interfaces can provide eyes-free inputs without restricting physical movement
Social applications could utilize the satisfying push and aesthetics of the buttons to inspire conservation and facilitate social embodied interactions
And we believe that this is only the beginning!
FabriClick pushbuttons enable eyes-free inputs on wearable e-textiles by interweaving tactile pushbuttons into the fabrics
The frame system allowed us to streamline the workflow of producing multilayer multi machine buttons, making them accurate and reproducible
To invite makers, designers, researchers, and practitioners to continue experimenting and approaching older problems from new perspectives
We have open-sourced the schematics and design files of this project on GitHub you can find them through the link.
For more details, please check our paper
Thanks for your attention and have fun reading!