A Sensor That Detects Multiple Stimuli At Once Using Color

Researchers at EPFL’s Reconfigurable Robotics Lab (RRL) have designed a sensor that can simultaneously detect multiple stimuli – such as bending, stretching, compression, and temperature shifts – by using color. The new sensor shows promise for use in creating more autonomous soft robots and in wearable devices.

The device, called ChromoSense, uses a translucent rubber cylinder that is divided into three sections, each dyed a different color – red, green, and blue. ChromoSense uses an LED at the top of the cylinder to send light through its core. As the device is bent or stretched, changes in the light’s path through the different colored sections are detected by a miniaturized spectral meter at the bottom of the device. The device also uses a special dye that loses its color when it is heated, enabling it to detect temperature changes. This new approach allows ChromoSense to simultaneously sense multiple mechanical and temperature stimuli. 

“Imagine you are drinking three different flavors of slushie through three different straws at once: the proportion of each flavor you get changes if you bend or twist the straws. This is the same principle that ChromoSense uses: it perceives changes in light traveling through the colored sections as the geometry of those sections deforms,” explained Jamie Paik, founder and director of RRL

As ChromoSense has a simple mechanical structure and utilizes color instead of cameras, it has the potential to be mass produced at a low cost. 

“For soft robots to serve us better in our daily lives, they need to be able to sense what we are doing. Traditionally, the fastest and most inexpensive way to do this has been through vision-based systems, which capture all of our activities and then extract the necessary data. ChromoSense allows for more targeted, information-dense readings, and the sensor can be easily embedded into different materials for different tasks,” said Paik.