Particle image velocimetry is an experimental technique for measuring the velocity field of a moving fluid by tracking small particles dispersed within the flow. To extend this technique to the study of fluid temperature, we propose a novel tracer particle which enables direct measurement of the velocity, while acting as a temperature sensor by increasing its fluorescence intensity when the local fluid temperature rises above 32°C. Thermoresponsive tracers are prepared by incorporating nitrobenzofurazan functionalized hydrogels within optically transparent polydimethylsiloxane microspheres. We demonstrate the application of the tracers in the study of forced thermal convection in water around a heated cylinder in an open channel.
Mechanochromism of polymer-dye blends can be used to formulate novel pressure sensors for fluid mechanics and hydrology, where the use of traditional electromechanical transducers may be limited by environmental factors. Here, we investigate optomechanical properties of a mechanochromic blend of thermoplastic polyurethane and 0.5 wt% bis(benzoxazolyl)stilbene fluorescent dye. We characterize the response of this soft active material in a stress relaxation test by simultaneous acquisition of the tensile load, the mechanical deformation, and the fluorescence emission.
This study seeks to investigate the feasibility of energy harvesting from mechanical buckling of ionic polymer metal composites (IPMCs) induced by a steady ﬂuid ﬂow. In particular, we propose a harvesting device composed of a paddle wheel, a slider-crank mechanism, and two IPMCs clamped at both their ends. We test the system in a water tunnel to estimate the eﬀects of the ﬂow speed and the shunting resistance on power harvesting. The classical post-buckling theory of inextensible rods is utilized, in conjunction with a black-box model for IPMC sensing, to interpret experimental results.
In this paper, we study the charge dynamics of ionic polymer metal composites (IPMCs) in response to an
imposed time-varying flexural deformation. IPMC chemoelectromechanical behavior is described through the
Poisson-Nernst-Planck framework, and the method of matched asymptotic expansions is utilized to establish a
closed-form solution for the electric potential and counterion concentration in the IPMC. This solution is, in
turn, leveraged to derive a mathematically tractable distributed circuit model of IPMC sensing.