Van de Graaff generator
Other electrostatic machines like the Wimshurst machine or Bonetti machine work similarly to the Van De Graaff; charge is transported by moving plates, disks, or cylinders to a high voltage electrode. For these generators, however, corona discharge from exposed metal parts at high potentials and poorer insulation result in smaller voltages. In an electrostatic generator, the rate of charge transported (current) to the high-voltage electrode is very small. After the machine is started, the voltage on the terminal electrode increases until the leakage current from the electrode equals the rate of charge transport. Therefore, leakage from the terminal determines the maximum voltage attainable. In the Van de Graaff generator, the belt allows the transport of charge into the interior of a large hollow spherical electrode. This is the ideal shape to minimize leakage and corona discharge, so the Van de Graaff generator can produce the greatest voltage. This is why the Van de Graaff design has been used for all electrostatic particle accelerators. In general, the larger the diameter and the smoother the sphere is, the higher the voltage that can be achieved.
Electrostatic force microscope
Electrostatic force microscopy (EFM) is a type of dynamic non-contact atomic force microscopy where the electrostatic force is probed. ("Dynamic" here means that the cantilever is oscillating and does not make contact with the sample). This force arises due to the attraction or repulsion of separated charges. It is a long-range force and can be detected 100 nm or more from the sample. 
For example, consider a conductive cantilever tip and sample which are separated a distance "z" usually by a vacuum. A bias voltage between tip and sample is applied by an external battery forming a capacitor, "C", between the two. The capacitance of the system depends on the geometry of the tip and sample. The total energy stored in that capacitor is "U = ½ C⋅ΔV". The work done by the battery to maintain a constant voltage, "ΔV", between the capacitor plates (tip and sample) is "-2U". By definition, taking the negative gradient of the total energy "U = -U" gives the force. The "z" component of the force (the force along the axis connecting the tip and sample) is thus: