Cr-N Strain-Gauge-Type Precision Displacement Sensor for Measuring Positions of Micro Stage

A strain-gauge-type precision displacement sensor, which is developed for a usage of micro-XY stage, is described in this paper. A thin-film strain-gauge element, which is made by Cr-N alloy, is directly fabricated on the base of the strain gauge. The direct fabrication and using the Cr-N element are expected to achieve higher sensitivity for displacement detection and better stability against the change of ambient temperature. In this study, several designs of the thin-film strain gauge, including both of two-gauge-type and four-gauge-type, are prepared to compare sensor performances such as sensitivity, stability and so on. The designed patterns of the strain-gauge element are directly fabricated on zirconia plates by using photolithography processes. The fabricated strain gauges are then evaluated as precision displacement sensors. At first, stability of the fabricated Cr-N strain-gauge-type displacement sensor was confirmed by comparing with the one made by a conventional strain gauge. Resolution of the fabricated Cr-N strain-gauge-type displacement sensors was then evaluated by comparing with a commercially-available laser displacement sensor, while giving sub-micrometer-order deformation to the strain-gauge-type displacement sensor. Details of the design, fabrication and evaluation results of the Cr-N strain-gauge-type displacement sensor are described.