Investigation on Measurement of Liquid Volume by using Bend Sensor and Linear Extension Spring

In this paper, we report the investigation on measurement of liquid volume by using bend sensor and linear extension spring. The bend sensor is mounted in U-shaped laterally to a vertically suspended spring. A liquid container is attached to the bottom end of the spring. As the volume of the liquid in the container changes, the elongation length of the spring also gets changes. There will be corresponding changes in the bending radius of the mounted bend sensor. The changes in bending radius will introduce changes in resistance of the bend sensor. A resistance to frequency conversion signal processing circuit is used to convert the changes in resistance to frequency counts. Further, the output of signal processing circuit is processed by a microcontroller. The resolution in measurement is found to be within the range of
$3.9-12.6\ \mu\mathrm{L}$
. The advantages of the propose system is that the measurement of liquid volume is independent of refractive index or colour of the liquids and also can be used for volatile liquid.