The video linked below displays test results. The plot shows the change in the relative capacitance in parts per million. Note that a load results in a change of approximately 1.5 microstrains, which demonstrates the high senstivity of a sensing patch.
We can now investigate the plot to appreciate some sensing properties(see the figure below). First, the jumps in capacitance after the addiction/subtraction of weights are linear, which confirms that the polymer remains elastic at small strain. This property allows simple signal processing to determine the level of strain under a patch. Second, the level of capacitance does not return to zero after the beam is completely unloaded. This is due to the material locking phenomenon, where the sensing material is tensioned for the first time after its application. This phenomenon can be minimized by pre-tensioning the sensor during its installation. Third, a slope in the data is observed during the unloading stage. This slope represents a slow response of the polymer during its contraction. This effect can be minimized by using stiffer bonding agents between the sensing patch and the monitored surface.
International and Multi-Disciplinary Collaborations
The Sensing Skin has been originally developped in collaboration with Drs. Matthias Kollosche and Guggi Kofod, from the Institut fïr Physik und Astronomie of Universität Potsdam, Germany.
Today, the collaboration with Universität Potsdam is continuing with Prof. Dr. Reimund Gerhard and Dr. Matthias Kollosche. Here at Iowa State University, the research effort is branching to additional discplines with the active participation of other researchers, including Dr. Randy Geiger, from Electrical and Computer Engineering, and Drs. Michael Kessler, Nicola Bowler, and Krishna Rajan from Materials Science and Engineering.
Funding granted by IAWind. press release
ASCE Civil Engineering Magazine: 'Sensing Skin' Remotely Detects Cracks in Structures. Vol. 81, No. 12, December 2011, pg. 42
Scientific American: Instant Health Checks for Buildings and Bridges.
MIT news: A 'sensing skin' for concrete. link
MIT press release on the sensing skin. link
Selected related coverage:
- Gizmag: 'Sensing skin' could detect cracks in concrete structures. link
- PCWorld : Researchers Propose 'skinning' Bridges for Fault Detection. link
- EE Times : Researchers Develop 'electronic skin' for Structural Faults. link
- Softpedia: Monitor Sensor Coatings for Buildings Developed. link
Ernest A. Herzog Award by the Boston Society of Civil Engineers section of the ASCE for the technical paper A Sensing Skin for Large-Scale Surface Monitoring of Infrastructures
. The Herzog award is established to promote awareness and recognize innovative improvements to infrastructure. paper
Successful tests of PolyPower sensor material for structural health monitoring (story from Danfoss). link