Since the invention of optical tweezers, optical manipulation has advanced significantly in scientific areas such as atomic physics, optics and biological science. Especially in the past decade, numerous optical beams and nanoscale devices have been proposed to mechanically act on nanoparticles in increasingly precise, stable and flexible ways. Both the linear and angular momenta of light can be exploited to produce optical tractor beams, tweezers and optical torque from the microscale to the nanoscale. Research on optical forces helps to reveal the nature of light–matter interactions and to resolve the fundamental aspects, which require an appropriate description of momenta and the forces on objects in matter. In this review, starting from basic theories and computational approaches, we highlight the latest optical trapping configurations and their applications in bioscience, as well as recent advances down to the nanoscale. Finally, we discuss the future prospects of nanomanipulation, which has considerable potential applications in a variety of scientific fields and everyday life.

No abstract

An individual carbon nanocoil was clamped between two AFM cantilevers and loaded in tension to a maximum relative elongation of ∼42%. The deformation of the nanocoil agrees well with an analytical model of the spring constant that accounts for the geometric nonlinearity. The nanocoil behaves like an elastic spring with a spring constant K of 0.12 N/m in the low strain region. No plastic deformation was detected. High-resolution microscopy images and the electron energy loss spectrum (EELS) indicate that the nanocoils are amorphous with a sp 2 /sp 3 bonded-carbon ratio of ∼4:1.

Many experiments on the mechanics of nanostructures require the creation of rigid clamps at specific locations. In this work, electron-beam-induced deposition ͑EBID͒ has been used to deposit carbon films that are similar to those that have recently been used for clamping nanostructures. The film deposition rate was accelerated by placing a paraffin source of hydrocarbon near the area where the EBID deposits were made. High-resolution transmission electron microscopy, electron-energy-loss spectroscopy, Raman spectroscopy, secondary-ion-mass spectrometry, and nanoindentation were used to characterize the chemical composition and the mechanics of the carbonaceous deposits. The typical EBID deposit was found to be hydrogenated amorphous carbon ͑a-C:H͒ having more sp 2 -than sp 3 -bonded carbon. Nanoindentation tests revealed a hardness of ϳ4 GPa and an elastic modulus of 30-60 GPa, depending on the accelerating voltage. This reflects a relatively soft film, which is built out of precursor molecular ions impacting the growing surface layer with low energies. The use of such deposits as clamps for tensile tests of poly͑acrylonitrile͒-based carbon nanofibers loaded between opposing atomic force microscope cantilevers is presented as an example application

A series of observations of polymer sheathing in multiwalled carbon nanotube (MWCNT)−polycarbonate composites are presented. This sheathing was observed in images of the composite fracture surface and is consistent with diameter distributions of the as-received and embedded MWCNTs. A novel nanomanipulation experiment, where the sheathing balls up when contacted by an AFM tip, confirms this phenomenon. This sheathing layer is direct evidence of substantial MWCNT−polymer interaction and will influence the mechanical properties of MWCNTpolymer composites.Due to the outstanding physical properties of carbon nanotubes, intense activity is being devoted to the development of carbon nanotube-polymer composites.1 Specifically, carbon nanotube-reinforced polymer composites have demonstrated high strength and stiffness, 2 which suggest their potential use as alternative materials for structural applications. Multifunctional nanotube-polymer composites are also under development, where in addition to improved mechanical properties, increases in electrical conductivity 3 and improved thermal properties 4 are obtained with small amounts of embedded nanotubes.One of the significant differences between micron-sized carbon fiber-filled polymers and nanotube-filled polymers is the large interfacial area of the nanotubes. This interfacial area provides an opportunity for altering the mobility and properties of a significant volume of polymer near the interface (i.e., the interphase region). Both the interface and interphase regions will play key roles in optimizing load transfer between the nanotube and the polymer matrix. While for traditional composites a variety of experimental techniques have been developed in an effort to quantify the fibermatrix interface, 5 for nanotube-polymer composites these tests are exceedingly difficult because of the small size of the nanotubes. In the process of developing nanoscale pullout tests of individual multiwalled carbon nanotubes from a polymer matrix, we have found several forms of evidence that suggest multiple polymer layers sheath the embedded nanotubes. This polymer sheathing is consistent with models of a nonbulk polymer interphase region that has been identified in nanotube-polymer composite systems. 6 The results presented in this paper are consistent with the findings of other researchers regarding the existence of intimate MWCNT-polymer interaction in nanotubepolymer composites. For example, strong polymer adherence has been reported in previous TEM studies of nanotubepolymer nanocomposite samples.7 Potschke et al. studied the rheological behavior of nanotube-polycarbonate composites, and their SEM observation of the fracture surface showed that the apparent nanotube diameters at the fracture surface were larger than the diameters of the original carbon nanotube material, indicating significant polymer wetting on the nanotube surface. 8 However, to date a detailed study of this polymer sheathing phenomenon in carbon nanotubepolymer nanocomposites has not been undertaken. ...