DynaButtons Feel the Force

DynaButtons are dynamic shape-shifting buttons powered by advanced electroosmotic pumps that provide haptic feedback and sensing.

Nick Bild
2 months agoSensors
A user interacting with a DynaButton (📷: T. Rae-Grant et al.)

An increasing number of user interfaces are going digital, with touchscreens becoming the preferred choice for many applications. But while touchscreens offer a tremendous amount of flexibility, there is something missing. The dull thud of a finger tapping on a sheet of glass leaves many longing for the clickety-clack of a physical button. The sound and haptic feedback make for a much more pleasant user experience.

These days, buttons have some tricks up their sleeves too — watch out touchscreens! The haptic feedback of certain types of buttons can be dynamically altered to provide more or less resistance, or even force feedback. One of the best known examples of this type of button is the active trigger of the PlayStation 5 DualSense controller. Unfortunately, the motors, servos and other components needed to drive these systems tend to be complex, bulky, and expensive, which makes them impractical for widespread use.

Hydraulic systems that leverage electroosmotic pumps have emerged as a potential solution to this problem. They can be very small, inexpensive, and simple to fabricate. As such, buttons that use electroosmotic pumps for haptics could make more intelligent physical buttons a commonplace interface element. But before we get there, further development of control systems and feedback mechanisms is needed.

A team led by researchers at Carnegie Mellon University has advanced the state of the art in electroosmotic pump technology, and has further developed a practical sensing system. These advancements were leveraged to create what they call DynaButtons, which are a dynamic user interface button. These buttons can rapidly shift their shapes, provide haptic feedback, and capture user inputs.

A DynaButton is composed of a number of layers that are encased in silicone. The layers are split into three functional areas — the reservoir layer that stores a liquid, the pump layer that causes the liquid to be transported on demand, and the output layer that fluid is pumped into and out of. A force-sensitive resistor is included underneath the button for touch sensing, and a Teensy 4.0 microcontroller development board controls the device.

The unique design of the button allowed it to achieve a 300 percent greater flow rate as compared to existing devices that leverage electroosmotic pumps. That factor, in combination with the button’s sensing capabilities and simplicity could make it a good choice for real-world applications in the near future.

To demonstrate the possibilities, the researchers created an implementation of their technology in a single button. It was shown to be able to move in a variety of ways, interact with a finger, and even maintain its height at a fixed position relative to a laser distance sensor. You won’t want to miss that last demonstration in particular in the video below.

Moving forward, the team is looking for opportunities to further optimize their design. They are also exploring additional avenues for interaction and sensing.

Nick Bild
R&D, creativity, and building the next big thing you never knew you wanted are my specialties.
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