- Electrostatic deflection (structural element)
molecular physics/ nanotechnology, electrostatic deflection is the deformationof a beam-like structure/element bent by an electric field(Fig. 1). It can be due to interaction between electrostaticfields and net charge or electric polarizationeffects. The beam-like structure/element is generally cantilevered (fix at one of its ends). In nanomaterials, carbon nanotubes(CNTs) are typical ones for electrostatic deflections. Mechanismsof electric deflection due to electric polarizationcan be understood as follows:
As show in Fig.2, when a
materialis brought into an electric field(E), the field tends to shift the positive charge(in red) and the negative charge(in blue) in opposite directions. Thus, induced dipolesare created. Fig. 3 shows a beam-like structure/element in an electric field. The interaction between the molecular dipole momentand the electric fieldresults an induced torque(T). Then this torquetends to align the beam toward the direction of field.
In case of a cantilevered CNT (Fig. 1), it would be bent to the field direction. Meanwhile the electrically induced
torqueand stiffnessof the CNT compete against each other. This deformationhas been observed in experiments(Poncharal Science 283, 1513 (1999)) and Wei APL 79, 4527 (2001)). This property is an important characteristicfor CNTs promising nanoelectromechanical systemsapplications, as well as for their fabrication, separation and electromanipulation. Recently, several nanoelectromechanical systemsbased on cantilevered CNTs have been reported such as: nanorelays(Kinaret APL 82, 1287 (2003),(Lee Nano Lett 4, 2027 (2004)), nanoswitches(Jang APL 87, 163114 (2005)), nanotweezers(Akita APL 79, 1691 (2001)) and feedback device(Ke APL 85, 681 (2004)) which are designed for memory, sensingor actuationuses. Furthermore, theoreticalstudies have been carried out to try to get a full understanding of the electric deflection of carbon nanotubes(Z. Wang et al., PRB, 76, 195434 (2007)).
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