Self-calibrated Analog-Front-End Circuitry for Ultra Low Power Strain Sensors
D. Kuramoto, T. Hamasaki (Hiroshima Inst. of Techn., Japan)
New concept of analog-front-end circuitry for strain sensors is proposed in order to realize ultra low power devices for structure health monitoring. In this paper, instead of the commonly used 120Ω strain gauge, we utilize 1 kΩ strain gauge considering the tradeoff between signal to noise ratio and the power consumption for the actual SHM application conditions. From the point of long-term autonomous SHM, the key objective is the deformation due to cumulative plastic strain of aged deterioration of the structure. However, there is a problem that offset calibration is necessary for strain gauges. Also, when performing long-term monitoring periodically, it is desirable to automatically perform offset calibration on an analog circuitry. Therefore, in this paper, we design and fabricate a self-calibrated analog front circuitry with 1 kΩ strain gauges also considering the lower excitation voltage with appropriate noise level. Fabricated sensor circuitry achieves 99% power reduction compared with the conventional 120Ω strain sensor configuration for the sake of cumulative plastic strain diagnostics.
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