Connect the laser source, optical splitter, optical power meter, and TFP as shown in Fig. 1a.
Place a clean glass slide on the translation stage of the microscope, pipette a droplet of particle (3-μm-diameter silica) suspension (0.1 mL) on the glass slide with a micro-syringe. Adjust the six-axis manipulator to move the TFP inside the suspension and adjust the microscope until the TFP and particles appear inside the field of view. Change the objectives from ×5 to ×100 to have a clear view of the TFP and particles. Move the TFP to get close to particles by adjusting the six-axis manipulator.
Turn on the laser source, tune the knob on the laser source until the optical power displayed on the optical power meter is 2 mW. The particles beside the TFP axis will be trapped to the axis by the transverse optical gradient force as shown in Fig. 2a-c.
Increase the optical power displayed on the power meter to 4.5 mW. The particles along the TFP axis will be trapped and/or driven away by the dominant optical gradient force and scattering force, respectively, as shown in Fig. 2d,e.
Move the TFP in different directions, the trapped and driven particles can be manipulated flexibly in different directions, as shown in Fig. 2f.
Keep the optical power displayed on the power meter at 4.5 mW, and move the TFP until the particles are along the TFP axis but with different distances. You will see single particle being trapped or driven away (see Supplementary Video 1 and Video 2). Different manipulation distances (DM) for particles with different axial working distances (DA) and optical powers launched into the TFP are shown in Fig. 3a and b, respectively.
Tune the optical power displayed on the power meter at 2.8 mW, move the TFP to trap and pick up individual particles and deliver them to designated positions to form desired patterns (see Supplementary Video 3).
Tune the optical power displayed on the optical power meter at 3.9 mW, move the TFP to drive particles to designated positions to form desired patterns (see Supplementary Video 4).
Combine the abilities of trapping and driving, different patterns can be arranged as shown in Fig. 4.
To manipulate sub-micron sized particles, using another clean glass slide and pipette a droplet of particle (0.7-μm-diameter silica) suspension (0.1 mL) on the slide, follow the procedure as described in 2) of section Manipulation of particles and cells.
Turn on the laser source, tune the knob on the laser source until the optical power displayed on the power meter is 3.3 mW. The particle near the TFP tip will be trapped by the dominant optical gradient force as shown in Fig. 5aI. For those particles with a larger distance to the TFP tip, they will be driven away by the dominant optical scattering force as shown in Fig. 5aII.
To manipulate cells, using another clean glass slide and pipette a droplet of yeast cell suspension (0.1 mL) on the slide, follow the procedures as described in 2) of section Manipulation of particles and cells.
Turn on the laser source, tune the knob on the laser source until the optical power displayed on the power meter is 2.8 mW, the yeast cell near the TFP tip will be trapped by the dominant optical gradient force as shown in Fig. 5bI. For those cells with a larger distance to the TFP tip, they will be driven away by the dominant optical scattering force as shown in Fig. 5bII.
Change a new glass slide for manipulation of E. coli bacteria.
Follow the method for manipulation of yeast cells, the power displayed on the meter is also 2.8 mW, the trapping and driving of E. coli bacteria are shown in Fig. 5cI and cII, respectively.
After finishing manipulation of each kind of particles and cells, remember to turn off the laser.