Shear-sensitive polymer dispersed liquid crystal

Abstract

Polymer dispersed liquid crystal has been developed as a shear stress sensor, showing a great signal-to-noise ratio with a high temporal bandwidth. Traditional shear sensing liquid crystal techniques are known to be irreversible processes under practical test conditions. The introduction of polymer into the liquid crystal gives the shear-sensor an additional temporal bandwidth that can be utilized for detecting unsteady flow phenomena. Exploiting a revolutionary dynamic birefringence detecting system known as "Milliview", a series of liquid crystal polymer combinations were tested in a wind tunnel apparatus. The signal strength and the reversibility of the tested combinations are summarized in this paper. The preliminary results showed promising potential in this new sensor system. It demonstrated the capability of the sensor in commercial wind tunnel applications. The dynamic range and the bandwidth of the sensor can be adjusted to fit different application needs. Few combinations presented qualities both in high dynamic range and in broad bandwidth, making them ideal broad purpose sensors.