Threshold trapping electric potential

Figure 17 shows the ratio of the threshold trapping electric potential differences for the Bosch and HF channels obtained from the calculations along with the experimental values obtained for a number of different particle types. The calculated value of 0.46 is in reasonable agreement with that measured for spores, but die values for the other types of particles are much larger. 

Figure 17, The ratio of the threshold trapping electric potential differences for the Bosch and HF channels as obtained from the calculations and as measured for several different types of particles.

One possible explanation for this difference between the experimental and theoretical values for the ratio of threshold trapping potentials is the presence of particle-particle interactions that may perturb the electric field gradient present between the posts. The local perturbation to the field created by one particle may amplify the dielectrophoretic force acting on a nearby particle. A large number of such interactions may cascade, resulting in a significant enhancement of the dielectrophoretic force. This could result in direct contact between particles and van der Waals forces would then act to keep the particle ensemble together. 

---