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Nano-structured carbon sensor for simultaneous measurement of load and temperature at mechanically strained surfaces

: Biehl, S.; Lüthje, H.; Bandorf, R.

Univ. of Minho:
Eurosensors XVII. Book of Abstracts
Guimaraes, 2003
ISBN: 972-98603-1-9
Eurosensors <17, 2003, Guimaraes, Portugal>
Conference Paper
Fraunhofer IST ()
force sensor; diamond like carbon; piezoresistive

Future innovations in important technical areas will depend on smart surfaces which combine protection against wear and corrosion with interactive control of the related system. Therefore multifunctional coatings with integrated sensors are needed, which will detect essential parameters of the surface like human skin is doing. This paper deals with the development of novel multifunctional coatings based on nano structured carbon-hydrogen films. The layers were optimized with respect to mechnical and sensorical requirements. For the first time it will be reported, that diamond-like corbon films have been developed, which can be used simultaneously for force/pressure and temperature measurement. Moreover, the quasi monolithic layers showed excellent tribological properties with respect to wear protection and low friction. This new type of thin film sensor has the advantage over existing sensors that it can be used in areas under high mechanical load and therefore enables direct measurements in the contact zone of mechanical constructions. For layers of 5 M base resistivity K-factors as high as 28 k /N were obtained. The thermal variation of resistance resulted between 20 - 110°C to 7,7 and 0,2 k /K, respectively. The diamond-like carbon films exhibits high hardness in the range of 15-30 GPa and therefore allowed measurement of normal forces without almost no deformation of the construction. The fabrication was done by means of sputtering and plasma CVD techniques. The friction against steel was as low as 0,1. It turned out, that the novel sensor layer can be used in various technical applications. Examples of characterization and applications will be discussed.