Separation of Nanocolloids by Taylor Cone Harmonics

The conducting Taylor cone can activate specified harmonics of Laplace equation near the cone and can generate field maxima at multiple discrete polar angles. As the nanocolloids are ejected out from the cone tip, the difference of dominating forces in axial and transverse direction defines size-dependent initial angle before the colloids are trapped by the field maxima of the harmonics at the closest polar angle. This size-dependent selection of harmonics governs the different size colloids to travel along different trajectories and form separated deposition in the downstream of the electrospray. This electrospray-based separation of nanocolloids is successfully used to detect DNA hybridization. A family of cone shape is generated by changing voltage in a finite range. Variation of Taylor cone angle changes the harmonics and the trajectory of colloid is found to shift to a larger polar angle under higher voltage.