An improved interaction between human and machine is vital for the ongoing automation of our modern life style. However, since practically no machines would be working without the presence of sensors, humans are heavily dependent on sensor technology.
Most sensor systems today are limited to indirect measurement of averaged macroscopic properties and limited in numbers by their cost. Thin film sensors, on the contrary, can be applied locally inside component surfaces and due to the production technology the cost of multiplicity is not prohibitive.
Results and conclusions
The present COSMOS project (Components and Smart Machines with Micro-Nano Surface Embedded Sensors) has successfully merged two non-overlapping core competences: (i) clean room based sensor design and fabrication represented by Acreo Sweden and SINTEF in Norway, and (ii) tribology related hard coatings represented by VTT in Finland and Danish Technological Institute in Denmark.
The main objective of the COSMOS project was to develop a prototype of a sensor, buried under a wear-resistant coating. The development was based on the know-how and the fabrication facilities of the involved partners. The main obstacle by creating an embedded sensor is related to the fabrication of a sufficiently insulating intermediate layer to be deposited on e.g. stainless steel as known from traditional wafer processing.
A series of sensor fabrication experiments was conducted applying a shadow-based masking technique. Based on this series of experiments it was possible to quantify the insulating properties of the underlying isolation layers. An insulating layer composed of only Atomic Layer Deposition of Al2O3 or only Dual Magnetron Sputtering of Al2O3 appeared to be insufficient isolation for sensor fabrication. The best result was obtained for a multilayer coating system composed of either (i) Atomic Layer Deposition of Al2O3 followed by Dual Magnetron Deposition of Al2O3, or (ii) Several layers of Diamond Like Carbon (Ta:DLC), or (iii) a multilayer system composed of several layers of Al2O3/Cr2O3. Pure sensor adhesion to the underlying insulating layer was observed to be improved significantly by treating the substrate with implantation of oxygen. The final surface embedded temperature sensor was buried under Diamond Like Carbon (DLC) revealing promising properties in industrial applications.
The ideas and the visions of the COSMOS project were communicated to relevant industrial partners in Europe. The development and implementation on more complicated geometries will be continued in COSMOS II.
Project presentation: Kick-off in May 2006 (ppt)
Project duration: May 2006 - March 2008