US Patent 7489143 - Nanogripper with hold detection

http://www.freepatentsonline.com/7489143.html

Nanogrippers (aka nanotweezers) have been implemented by a variety of materials including nanotubes and silicon. In order to assure proper gripping an optical feedback system has been used. This patent teaches an alternative solution based on electrostatic detection. Claim 1 reads:

1. A nanogripper device comprising:

a pair of arms that is opened and closed freely;

an electrostatic actuator that drives the pair of arms to open/close the arms;

an electrostatic capacity detection unit that detects an electrostatic capacity of the electrostatic actuator; and

a hold detection unit that detects that a sample has been gripped with the pair of arms based upon detecting a point of inflection of a curve representing a change occurring in the electrostatic capacity as a function of a voltage applied to the electrostatic actuator detected by the electrostatic capacity detection unit while closing the arms.