Manipulator of particle utilizing electrostatic force

Because manipulation of single particle is of great importance in areas of electronics and biology, we have been investigating an electrostatic manipulation system. A manipulator consisted of two parallel pin electrodes. When voltage was applied between the electrodes, electrophoresis force generated in non-uniform electrostatic field was applied to the particle near the tip of the electrode. The particle was captured by the application of the voltage and released from the manipulator by turning off the voltage application. It was possible to manipulate not only insulative but also conductive particles. However, if the particle was charged, Coulomb force and adhesion force prevented from releasing the particle when the voltage was turned off. This condition was apt to take place for small particles, less than 200 μm in diameter. An uneven electrode system was also developed to release the attached particle independently of the position of the manipulator. High voltage was applied to the electrodes instead of turning-off the voltage application to blow off the particle by the ionic wind generated in corona discharge field and the validity of this system was demonstrated. Three-dimensional field calculation was conducted to calculate the electrophoresis force and Coulomb force by the Finite Difference Method and compared to the measured force. It was deduced that the predominant force of particle adhesion is not electrophoresis force but Coulomb force due to triboelectrification.