Sensorial Surfaces-Embedding Sensor Structures Into the Surface of Materials

This paper describes the concept of sensorial surfaces in contrast to thin film or conventional microsensors. Examples for their application in the monitoring of bearings and hot or cold forming processes are given. Two manufacturing processes to embed the sensor structures into the surface of the part to be monitored are developed. The embedding makes the sensor structures less prone to failure caused by high mechanical loads. Sensorial surfaces consist of a thin-film layer package made from insulating and conductive layers. The first process embeds the sensor structure into the insulating layer of the layer package. Electrochemical micromachining is used for the second process and the 3-D structure of a strain gauge is manufactured 45 μm deep into hardened 100Cr6 steel in <;10 s. This makes the process significantly faster than conventional photolithography and etching or laser processes with virtually no thermal stress on the workpiece.