Controlled manipulation of a bio-particle using trolling mode atomic force microscope: a simulation study

In the present study, a novel strategy based on particle motion mode is introduced to control the manipulation process of a bio-particle using trolling mode atomic force microscope. To achieve this goal, the reduced governing partial differential equations and the standard form of the system are used as a model for the system dynamic behavior. The governing equations take 6 degrees of freedom into account including extension, torsion, and two lateral bendings of the microcantilever as well as two lateral bendings of the nanoneedle. Manipulation process of the 500 nm radius particle on the substrate includes two phases named sticking and sliding. Sticking of the particle to the substrate brings about an offset error which is predicted by a novel neural network. The estimated error is added to the predetermined distance to the reference point; thus, the overall distance that the substrate ought to traverse is defined and given to the sliding phase controller as an input. In sliding phase, a proportional-integral-derivative controller and a Lead-lag compensator are utilized to control the velocity of substrate. Since in manipulation of an adhesive bio-particle any overshoot is prohibited, various methods are tested to find an appropriate controller without any overshoot. It is shown that a simple proportional controller can steer the particle to its target point with the most safety and without any overshoot.