Title :
Interfacial force sensor with force-feedback control
Author :
Joyce, S.A. ; Houston, J.E. ; Smith, B.K.
Author_Institution :
Sandia Nat. Lab., Albuquerque, NM, USA
Abstract :
A novel interfacial force microscope capable of measuring the forces between two surfaces over the entire range of surface separations, up to contact, has been developed. The design is centered around a differential capacitance displacement sensor where the common capacitor plate is supported by torsion bars. A force-feedback control system balances the interfacial forces at the sensor, maintaining the common capacitor plate at its rest position. This control eliminates the instability which occurs with the conventional cantilever-based force sensors when the attractive force gradient exceeds the mechanical stiffness of the cantilever. The ability to measure interfacial forces at surface separations smaller than this instability point using the feedback control is demonstrated.<>
Keywords :
atomic force microscopy; force measurement; differential capacitance displacement sensor; force sensors; force-feedback control; instability point; interfacial force microscope; surface separations; torsion bars; Bars; Capacitance; Capacitive sensors; Capacitors; Control systems; Force control; Force measurement; Force sensors; Mechanical sensors; Microscopy;
Conference_Titel :
Electron Devices Meeting, 1990. IEDM '90. Technical Digest., International
Conference_Location :
San Francisco, CA, USA
DOI :
10.1109/IEDM.1990.237122