Closed-Loop Control of Particles Based on Dielectrophoretic Actuation

The dielectrophoresis phenomenon exerts a force on dielectric particles placed in an inhomogeneous electric field. Using this property, we are able to control the displacement of microparticles by controlling the electric field in the workspace. It is achieved with an independent control of the voltages applied on electrodes placed inside a microchip. However, this type of system is characterized by a high nonlinearity regarding the position and the input voltages, making the control difficult. In our previous work, we proposed a new model based on Fourier series to compute the electric potential produced by electrodes. Here, we extend this model to compute the dielectrophoretic force applied to particles and propose a closed-loop controller based on the inversion of this model to achieve the trajectory control of micrometer-size particles. This inversion, based on the simulated annealing technique, is implemented and tested on simulations and experiments. The main issues for the implementation of closed-loop control on the experimental platform are discussed and overcome. Experiments are performed on microbeads of 10 $\mu$m in diameter and confirm that the inverse model computes the required voltages. The trajectory control of microparticles using closed-loop control at a frequency of 160 Hz is successfully achieved with a precision below 2 ${\mu }$m.