Add-on tactile buttons for mobile devices

Just launched today as an Indiegogo campaign (and over a quarter of the way to the goal as I am writing this) is an interesting product idea called DIMPLE from Dimple is basically a sticker with 4 buttons that can be added to many Android 4.0+ devices that support Near Field Communication (NFC) and the Dimple app. It requires no batteries because it uses energy that is radiated by the NFC reader.

Photo of Dimple button prototype.
DIMPLE buttons on the back of a phone. (Photo from press release kit.)

This prototype product is not one made specifically for people with disabilities—obviously from the response on Indiegogo, many people are interested in having customizable, programmable tactile buttons on their smartphones and tablets.

Dimple has potential accessibility uses. Such buttons would be useful for people who cannot see, because the buttons can be tactilely discerned and located. These users could associate some of their most commonly used functionality with the buttons and access them directly, instead of having to navigate through menus with the TalkBalk screen reader.

I do not know the exact capabilities of DIMPLE, NFC, or Android TalkBalk, but it would be very useful if the Dimple buttons could be used to access the TalkBalk screen reader or to generate virtual keyboard keystrokes. If capable, it would be very useful to have dedicated buttons to navigate through applications and make selections. This would be less fatiguing than making many swiping gestures to navigate.

The Bradley Tactile watch

On Kickstarter until August 15, 2013 is the Bradley timepiece project. It is a wristwatch that has tactile features that allow it to be used by people who are blind. It has an elegant design and greatly surpassed its fundraising goals.

The Bradley Timepiece tactile wristwatch. (Credit: Kickstarter by Eone)
The Bradley Timepiece tactile wristwatch. (Image credit: Kickstarter project by Eone)

Before this design, there were two general approaches to accessible wristwatches: talking watches and tactile watches like the one pictured below. Talking watches may not be easy to hear in noisy environments. With traditional tactile watches, users must lift a cover, which protects the delicate hands of the watch face.

A tactile watch with the cover open (image available without copyright from Wikipedia Commons)
A tactile watch with the cover open (image available without copyright from Wikipedia Commons)

The Bradley does away with hands and has two ball bearings that are magnetically attached to the movement, which makes the watch more durable. The position of the ball bearing on the face denotes the minutes, while the ball bearing around the periphery of the watch denotes the hours.

The Bradley timepiece is a good example of a design which incorporates Universal Design or Design for All principles. Its popularity on Kickstarter is more a testament to the attractiveness of the design than strictly to its utility for people who are blind. Such a watch can be used by people with and without visual impairments. The titanium watch has a very elegant appearance. My only worry is how much the titanium would scratch with everyday use, but that is not an accessibility topic!

See more information at the Eone Timepieces website. The site has a very elegant design, but unfortunately and ironically, the site is not very accessible in its current form (and is thus not an example of Universal Design).

Tactus tactile touchscreen prototype

Touchscreens can be particularly challenging to use for people who cannot see. All they feel is a featureless surface. Accessibility can be provided through speech using a number of different strategies, but finding onscreen buttons through audio is slower than finding tactile buttons.

Photograph of tactile bumps.

An edge view of a tactile layer that could be used as part of a touchscreen. (From Tactus Technologies.)

Tactus Technologies has been developing a touchscreen with areas that can raise and lower from the surface. Sumi Das for CNET posted a video and hands-on impressions a couple days ago. The technology uses microfluidics. For the buttons to raise up, liquid in the system is put under pressure–the higher the pressure, the taller and firmer the keys. The current version only offers one arrangement of buttons.

Currently, the technology is limited in that it’s a fixed single array. You wouldn’t be able to use the Tactus keyboard in both portrait and landscape mode, for example. But the goal is to make the third generation of the product dynamic. “The vision that we had was not just to have a keyboard or a button technology, but really to make a fully dynamic surface,” says cofounder Micah Yairi, “So you can envision the entire surface being able to raise and lower depending on what the application is that’s driving it.”


The current generation only offers a single array of raised buttons that would work in only one orientation. This would be helpful for allowing users to find the keyboard tactilely, for example, but this would offer no support for other applications. The user cannot tactilely find buttons or other controls for other applications on a smartphone or tablet.

Future versions may fix this limitation. Ideally, the microfluidic tactile “pixels” will be small enough so that various tactile shapes can be made. To make seamless shapes, the tactile pixels should not have significant gaps between them, but this may be technically difficult to do. With gaps in between the tactile pixels, the device could still be useful to tactile exploration, but the layout would likely be constrained to a grid of bumps. An onscreen button might have a single bump associated with it (multiple separate bumps should not be used to designate a single large key because it would feel like several separate controls). The bumps would allow people to locate controls, but without different shapes, it would be more difficult to identify the controls from touch alone.

From the video, it also looks that the current technology is not well suited to braille. Spots small enough for braille would not be sharp or tall enough for effective reading. (For more information, has a table of braille dimensions under different standards).