Table 1. The trapping capability of typical optical trapping systems.

Structures	Trapping stiffness	Trapping potential barrier	Particle size (radius)
Slot waveguide15	0.2 pN/(nm*W)	/	50 nm
Hybrid plasmonic waveguide17	~30 fN/(nm*W)	6.2 kBT/W	2.5 nm
Nanoslotted photonic crystal cavities18	/	4 kBT/mW	10 nm
Silicon photonic crystal resonators19	8.5 pN/(nm*W)	/	50 nm
Tapered photonic crystal waveguide21	/	9.7 kBT/mW	50 nm
Gold bowtie plasmonic tweezers24	~60 pN/(nm*W)	9.79 kBT/mW	10 nm
Photonic/plasmonic cavity26	80 pN/(nm*W)	21 kBT/mW	20 nm
Coaxial Plasmonic Apertures29	/	0.6 kBT/mW	5 nm
Slotted nanobeam cavity	0.4 pN/(nm*mW)	2000 kBT/mW	2 nm

The numbers are all numerically evaluated.