학술논문
Fabrication and testing of a high resolution extensometer based on resonant MEMS strain sensors
Document Type
Conference
Author
Source
2011 16th International Solid-State Sensors, Actuators and Microsystems Conference Solid-State Sensors, Actuators and Microsystems Conference (TRANSDUCERS), 2011 16th International. :1056-1059 Jun, 2011
Subject
Language
ISSN
2159-547X
2164-1641
2164-1641
Abstract
A novel type of linear extensometer with exceptionally high resolution of 4 nm based on MEMS resonant strain sensors bonded on steel and operating in a vacuum package is presented. The tool is implemented by means of a steel thin bar that can be pre-stressed in tension within two fixing anchors. The extension of the bar is detected by using two vacuum-packaged resonant MEMS double- ended tuning fork (DETF) sensors bonded on the bar with epoxy glue, one of which is utilized for temperature compensation. Both sensors are driven by a closed loop self-oscillating transresistance amplifier feedback scheme implemented on a PCB (Printed Circuit Board). On the same board, a microcontroller-based frequency measurement circuit is also implemented, which is able to count the square wave fronts of the MEMS oscillator output with a resolution of 20 nsec. The system provides a frequency noise of 0.2 Hz corresponding to an extension resolution of 4 nm for the extensometer. Nearly perfect temperature compensation of the frequency output is achieved in the temperature range 20–35 °C using the reference sensor.