Micro-Scale Chiplets Position Control

We address the problem of position control of micro-chips (chiplets) immersed in a fluid. An electric field, shaped by controlling the voltages of spiral-shaped electrodes, is used to reliably and accurately transport and position chiplets using dielectrophoretic forces. A lumped, capacitive-based (nonlinear) motion model is used to generate an open loop control policy. The spatial dependency of the capacitances is estimated using detailed electrostatic COMSOL simulations. The open loop policy is generated using a one step model predictive control approach. By exploiting the spatial symmetry and periodicity of the open loop control solution, a real-time control scheme is designed by applying simple algebraic operations to a base function defined on a finite domain. The chiplets position is tracked using image processing algorithms. We demonstrate the validity of our approach with an experiment where real-time control is used to move a chiplet for 1000 μm in a controlled manner. The results shown in this paper represent a critical step for the realization of a system that can digitally convert a design directly to the physical placement of micro-chips.