Smart Sensing for Intelligent Machinery: Part I - Highly Sensitive Flow Sensor with A Flexible Hinge and A Double-deck Annular Capacitor Array

In this paper, a new two-dimensional capacitive non-thermal micro flow sensor with high sensitivity is proposed, which include a novel annular-elliptical-notch flexure hinge to improve the sensitivity of a flexure hinge sensing pole (FHSP). The FHSP is used to be as a sensing element which can be tilting under the flow rates. Then, a double-deck annular capacitor array structure is installed around the FHSP to reflect the direction change. Correspondingly, the analytic formulas are deduced, and the analytic model is established respectively. Then, in theory, the sensibility formulations of the sensitive element and capacitance are derived respectively. And some related parameters which can enhanced the sensitivity of the flow sensor is analyzed. This capacitive micro flow sensor can detect air flow speeds ranging from zero to 8m/s with a sensitivity of 1.5x10-9 uF/uN and flow direction with 360 degree. The sensitivity of the micro flow sensor can be enhanced with excellent high-elastic material and more appropriate flexure hinge dimension. And with its high sensitivity, great dynamic responsibility and small zero drift on temperature, the flow sensor can be applied in coupling physical fields.