Ag Nanoparticle/Polydimethylsiloxane Composite Films for High-Sensitivity Strain Gauge Applications

This paper presents a type of Ag/polydimethylsiloxane (Ag/PDMS) nanocomposite material for use in strain gauge element applications. In these elements, the Ag nanoparticles work as conductive elements by electron tunneling and the PDMS forms the tunneling dielectricstructure. In our experiments, the piezoresistance and piezocapacitance characteristics of these Ag/PDMS composites have been studiedunder applied rain/stress. From the results, the gauge factors for piezoresistance and piezocapacitance can reach up to 153 and 224, respectively. Also, when acting as strain elements, the Ag/PDMS composites show fine levels of repeatability and stability. The results given here prove that the material can be used to form anew type of high-sensitivity element for sensor applications. The detectionmethod used for the sensor signals also offersdiversity by including both piezoresistance and piezocapacitance.

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.

A Method of Measuring Post-Yield Strain

Increasing interest has been shown recently in the measurement and interpretation of post-yield strains. Early investigators determined the nature and magnitude of such strains by observing the distortion of a grid of fine lines inscribed on the unstrained metal. A development of this method involved the use of a photographically deposited grid.In the present instance the initial requirement (August 1948) was for the measurement against time of strains of the order of 4 per cent. occurring as “ fast transients.”As the wire resistance strain gauge element was well established, it was natural to consider its extension to post-yield measurements, and it later became apparent that this had already been done by Swainger.