Measurement of propulsion force on particles under travelling-wave electric fields

Under travelling-wave electric fields, particles are propelled along an electrode array by the travelling-wave dielectrophoresis and the travelling-wave electroosmotic fluid flow. In the low frequency range, the horizontal movement of particles is dominated by the travelling-wave electroosmotic fluid flow. The fluid flow depends on the geometry of the electrode array. In order to design the electrode array, we have to measure the propulsion force accurately. However, there is no report about the accurate measurement of the propulsion force. To cope with this problem, we employed the “inclined gravity” to produce the opposite force. The method has developed by our laboratory for measuring the Dielectrophoretic force. It is applied to measure the propulsion force without any modifications. This paper presents the detailed experimental measurements of propulsion force on polystyrene particles in NaCl solution. The propulsion force was measured as a function of applied frequency, voltage, size of particle, and dimension of electrode.