Printing mechanical sensors

The researchers put slightly different plastics in each of the printer’s two print heads. One of the plastics changes color when it is stretched. Credit: A.J. Boydston, University of Washington

Researchers at the university of Washington have teamed up; engineers and chemists have been working together to invent a way to print, using a 3D printer mechanical sensors. The material changes its structure under stress and this result in color change that can be easily observed.

The 3D printer used has two printing head, to be able to print two different materials at the same time. The first head is uses polycaprolactone, the second one a polycaprolactone that contains a minimal percentage of spiropyran molecules (less than 0.5%). This is the molecule that changes color once subject to stress.

By varying the percentage and distribution of the molecule and the deposition of the second material researchers are able to create mechanical sensors that are sensitive to different types of stress.

They are envisaging application in building to signal stress in the structures, as well as insertion in football players helmets. Once hit the helmet can report the stress and the amount of it by making color appear on its surface.

Creating different types of sensors becomes a matter of changing the program and directing the printer to use different components in different places. This provide great flexibility at very low cost. It is also possibile to create an object that can report the history of stress over time.

Author - Roberto Saracco

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