Higher order dielectrophoretic force characterisation of non-spherical particles

A numerical method is presented for determination of higher-order dielectrophoretic forces on non-spherical particles. The method is applied to ellipsoidal particles of different dimensions subjected to electric fields with different degrees of non-uniformity. The results are compared against net force calculations using the Maxwell stress tensor method. The contribution from higher-order forces is shown to exceed the dielectrophoretic force based only on the dipole approximation when particle dimensions are comparable to the length scale of electric field non-uniformity. It is also shown that individual contributions from quadrupolar and octupolar dielectrophoretic forces strongly depend on particle aspect ratio