Engineering of pyro-electrohydrodynamic effect for microrheological characterization

In this work, focused on electrified fluid jets, the versatility of P-jet system is used to obtain measurements typical of a micro-rheometer directly from the analysis of videos and images acquired during the experimental phase, thus reducing the time analysis typical of a micro-rheometer that is computationally intensive.

Unlike a typical electrohydrodynamic-jet (e-jet) system, the pyro-electric system offers some advantages: it is nozzle-free and electrode-free because now the electric field is generated pyroelectrically.
The aim of this work is to use the p-jet system as a reliable micro-rheometer by finding a relationship between the fluid viscosity and p-jet measurements (such as number of jet events, first jet formation time and cone angle shape). PDMS as a fluid model at four different viscosities (10.000 – 30.000 – 60.000 – 100.000 cSt) was analyzed.

The results obtained show a strong dependence on viscosity. In particular, the shape of the cone angle becomes sharper as viscosity increases, departing from the ideal Taylor cone shape (as reported in the literature in the case of the traditional e-jet system).

The formation time of the first jet increases with increasing viscosity because the fluid with lower viscosity takes less time to be affected by the electric field generated pyroelectrically.
Finally, the number of jets increases as the viscosity decreases, as lower viscosity fluids are affected more rapidly than higher viscosity fluids, by electrostatic attraction.

A possible future perspective of this work is to provide the experimental data as input for an artificial neural network. This will lead to a computational solution of the problem, thus reducing the analysis time.