A new pressure sensor developed at the University of California, Riverside, may help to provide new insight into the nature of stress in devices which use the application of pressure.

Unlike commercially available pressure sensors, which tend to use only one colour and present results which are difficult to interpret, the new technology produces a range of colours which are easy to distinguish, providing a much clearer view of stress distribution.

Yadong Yin, an associate professor of chemistry, led the research which used a self-assembly method to string together gold nanoparticles. These were then embedded into a polymer film. When pressed, the polymer film deformed, stretching the gold nanoparticle strings. The increased separation of the nanoparticles alters the way they interact with light, changing their colour from blue to red with increasing pressure. When the pressure is removed, the colour changes persist, so that it is easy to see exactly where the stress occurs, and to what extent.

One big advantage of this nanoparticle technology is the fact that it can be painted onto contact surfaces; electronic stress sensors tend to be bulky, so that it is difficult to assess stress across a surface which is not uniform. This new technology, dubbed a “colorimetric stress memory sensor” by its developers, will overcome this issue.

Whilst the research used gold nanoparticles, the developers stated that silver and copper could also be used in the same way, and it’s thought that this new sensor film could have a wide range of applications. Painted onto crash test dummies, for example, it could highlight to automotive engineers the exact points at which stress is applied to the human body in a crash, helping them to design safer cars.

It would also be applicable to a wide range of devices which use springs to apply pressure, allowing designers even more insight into the pressures and stresses applied to the spring, the surrounding framework and the device as a whole.