A Simple Electrostatic Balance for the Milligram Range

We propose a method to realize the kilogram through electrical units, namely, the volt. The device is based on a simple plane plate electrostatic actuator used to counterbalance the weight force. The geometry of the electric field is characterized by changing the distance between the plates while maintaining a constant force and measuring the capacitance. This approach leads to the realization of a simple and compact device for the absolute measurement of small masses. The preliminary results show a relative uncertainty of 10^-3 for mass above 10 mg. A series of uncertainty sources has been pointed out. An improvement of one order of magnitude is expected by correcting these sources.