Novel method to reduce the transverse sensitivity of granular thin film strain gauges by modification of strain transfer

Strain gauges based on polyimide carrier foils and piezoresistive granular thin films are highly sensitive to strain. Unlike conventional metal foil, granular film strain gauges also have a pronounced sensitivity to strain acting in the transverse direction. A novel method that allows for the modification of the strain transfer is proposed and proven experimentally. The method is based on the creation of stand-alone polyimide paths, on top of which the piezoresistive thin film is located. In this way, the granular film hardly receives any transverse strain; hence, the transverse sensitivity is drastically reduced. A picosecond laser system can be used for both patterning of the thin film and for controlled ablation of polyimide in order to generate well-defined high path structures. The working principle of the method is demonstrated by simulation, followed by an experimental verification using measurements of the transverse gauge factor. Furthermore, the output signal of force transducers may be increased using granular thin film strain gauges of reduced transverse sensitivity.

Short communication: Automated testing of accelerometer transverse sensitivity with a flexure-based XY compliant stage

This paper presents the automated testing of accelerometer transverse sensitivity with a flexure-based compliant stage which can provide vibration on the XY plane. An experimental platform is set up, and the circular tracking error is first obtained to verify the feasibility of the stage. The transverse sensitivity of a three-axis piezoelectric accelerometer is subsequently tested, and it is below 3 %. The difference of the transverse sensitivity under various frequencies is 0.4 %, while the difference of measured direction angle is 2.49, which validates the accuracy of the proposed method.

Accelerometer transverse sensitivity calibration; validation and uncertainty estimation

The National Metrology Institute of South Africa (NMISA) has implemented a system to measure the transverse sensitivity of vibration transducers. As a mechanical device, the principle sensing axis of an accelerometer is not 100 % perpendicular to the mounting axis. This gives rise to the effect that the accelerometer will produce an electrical output even when a mechanical input perpendicular to the principle measurement axis is applied. The quantification of this "defect" parameter is of importance when high accuracy acceleration measurements are performed using accelerometers. This paper gives a brief overview of the system developed by the NMISA to measure the transverse sensitivity of vibration transducers. The paper then explores the validation of the system along with the uncertainty of measurement associated with the calibration system.