Piezoresistive strain sensing system for structural health and usage monitoring.

摘要

As silicon based sensor technology continues to experience accelerating growth, there exists an obvious trend toward combining MEMS transducers with increasingly sophisticated circuits. In those integrated sensing systems, on-chip circuits can perform such operations as amplification, calibration, averaging and data translation of sensor output, greatly enhancing the overall integrity and modularity of the system output.; The goal of this work is to develop a single chip polysilicon strain sensing system with digital readout and on-chip self-test and self-calibration for structural health and usage monitoring. Polysilicon cantilever beam off surface strain sensor and polysilicon membrane type strain sensor fabricated by MEMS technology have been investigated. A low power CMOS sensor interface was developed based on experimental results.; In the sensor interface design, we implemented noise-immune digital readout of sensor output by 10-bit resolution 1Msample/sec successive approximation analog to digital converter. Because the sensor array consumed considerable chip area, an area-efficient successive approximation register was implemented with minimum flip-flops. To further minimize the chip area and power consumption, voltage-division segmented R-2R ladder digital to analog converter was designed as DAC core, which was fabricated in single poly, twin-well, CMOS process.; On-chip sensor self-test was developed for safety critical applications based on the built-in redundancy of strain sensor array and successive approximation measurement technique. A novel hardware implementation was developed to meet the random successive approximation requirements based on programmable DAC output. To improve the quality of digital subsystem concurrent error detection, we developed a noninvasive built-in current sensor for IDDQ testing based on Hall effect for I/V conversion.; Experimental results were presented and discussed, which compared favorably to other reported designs.