Touch Goes Digital

After touch screens, researchers demonstrate electronic recording and replay of human touch

Researchers at the University of California, San Diego report a breakthrough in technology that could pave the way for digital systems to record, store, edit and replay information in a dimension that goes beyond what we can see or hear: touch.

“Touch was largely bypassed by the digital revolution, except for touch-screen displays, because it seemed too difficult to replicate what analog haptic devices – or human touch – can produce,” said Deli Wang, a professor of Electrical and Computer Engineering (ECE) in UC San Diego’s Jacobs School of Engineering. “But think about it: being able to reproduce the sense of touch in connection with audio and visual information could create a new communications revolution.”

In addition to uses in health and medicine, the communication of touch signals could have far-reaching implications for education, social networking, e-commerce, robotics, gaming, and military applications, among others. The sensors and sensor arrays reported in the paper are also fully transparent (see optical image of transparent ZnO TFT sensor array at right), which makes it particularly interesting for touch-screen applications in mobile devices.

“Our sense of touch plays a significant role in our daily lives, particularly in personal interaction, learning and child development, and that is especially true for the development of preemies,” said Nguyen, another senior author of this Scientific Reports paper. “We were approached by colleagues in the UC San Diego School of Medicine’s neonatology group to see if there was a way to record a session of a mother holding the baby, which could be replayed at a different time in an incubator.”

In their Scientific Reports paper, the researchers reported the electronic recording of touch contact and pressure using an active-matrix pressure sensor array made of transparent zinc-oxide (ZnO), thin-film transistors (TFTs). The companion tactile feedback display used an array of diaphragm actuators made of an acrylic-based dielectric elastomer with the structure of an interpenetrating polymer network (IPN). The polymer actuators’ actuation – the force and level of displacement – are modulated by adjusting both the voltage and charging time.

One of the critical challenges in developing touch systems is that the sensation is not one thing. It can involve the feeling of physical contact, force or pressure, hot and cold, texture and deformation, moisture or dryness, and pain or itching. “It makes it very difficult to fully record and reproduce the sense of touch,” said Wang.

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