Optical pressure sensors give robots a softer touch

Robots could soon have a softer, more human touch thanks to optical pressure sensors embedded in an artificial "skin."
Written by Andrew Nusca, Contributor

Robots could soon have a softer, more human touch thanks to optical pressure sensors embedded in an artificial "skin."

Robots are hardly known for their gentle actions -- it's either on or off, so to speak. Existing sensors, based on pressure switches and motor resistance, can't fully detect minor changes in pressure, nor discern different textures.

Why? Robots' electrical components aren't very flexible.

An engineer can coat a robot with sensors for better results, but large clusters of them can generate electromagnetic interference.

A team of researchers at Ghent University in Belgium have developed a flexible "skin" containing optical sensors, according to a New Scientist report.

Called an array waveguide sensor, the "skin," so to speak, consists of two layers of parallel polymer strips -- separated by a thin sheet of plastic -- that lie perpendicular to each other, forming a grid.

Arranged in this particular geometry, the polymer strips are fed light. With internal light reflection, they act like optical fibers. When pressure is applied anywhere on the "skin," the strips are pushed closer together, allowing light to escape from one set into the other.

[Read the full explanation (.pdf)]

From there, it's a simple signal loss concept: the more light leaks, the harder the "skin" is being pressed.

(In fact, it's a bit like the U.S. Army's "smart armor" we wrote about yesterday, which uses radio frequency in the same type of setup.)

Since the polymer strips are optical, interference isn't as much of a problem, and the strips can be packed as tightly as 125 micrometers apart.

The increase in touch sensitivity has myriad applications. In one example, surgical robots used in the emergency room will have more detail -- intelligence, even -- in how it interacts with the patient.

The leader of the project, Jeroen Missinne, presented the team's latest findings at the IMEC Flexible and Stretchable Electronics workshop in Ghent last week.

He is working on developing a complete prototype.

This post was originally published on Smartplanet.com

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