Existing keyboards incorporate either rigid push buttons inserted in a rollable sheet or a tactile sensor array patterned on a multi-layered soft sheet. These devices require complicated fabrication processes, and because of their brittle components, can only withstand a slight amount of bending or rolling.
The team based their new device on a sensor sheet they had previously developed, using a sheet of soft Ecoflex silicone rubber embedded with conductive carbon nanotubes that respond to the push of a finger by changing electrical resistance.
To guide users where to press, the researchers drew squares on the surface of the sheet to represent keys for each letter, number or other character. They used an artificial neural network to teach the keyboard to identify the intended letter or character based on the location and pressure of pushes—and associated changes in resistance—on the keyboard.
According to the team, the keyboard “worked perfectly and outperformed all existing portable keypads in terms of functionality, flexibility, disposability and cost”.
Each keyboard would cost $1, cheap enough that it could be tossed out and replaced if it stopped working, the researchers add.
