Exploring driving forces and liquid properties for electrokinetic energy conversion

This thesis presents an effort to understand electrokinetic energy conversion systems which are based on motion of ionic charges in micro- and nano-confinements. In particular, both experimentally and theoretically the utilization of different kind of liquids was investigated to convert mechanical to electrical energy in both on-chip and off-chip platforms by applying different forces to drive the fluids: a steady pressure, a periodic pressure and a centrifugal force. The fluids included Newtonian and non-Newtonian fluids. The content of this thesis is constructed as follows: Chapter 1 presents the aim and the outline of the thesis. Chapter 2 presents the fundamental and theoretical aspects of fluid flow in microchannels, introducing both electrostatics and electrokinetics, which concepts are encountered throughout the thesis. Chapter 3 shows the results of experiments when polymers are added to the solution in microchannels for streaming potential energy conversion. In chapter 4 we investigate the potential use of another kind of non-Newtonian fluid, namely a viscoelastic fluid for energy conversion. Chapter 5 shows theory and experiments for ballistic energy conversion systems using the centrifugal force. Chapter 6 offers conclusions based on this work and perspectives for future development.