- Small changes in the solvent of a colloidal suspension can have a large effect on the interaction energy of the suspended particles. This can be used to change a strong repulsion to a strong attraction, cause the particles to flocculate and precipitate (Witten 2004, pg. 6)
- Using this idea, maybe we can create a ferrofluid actuation system with a permanent magnet, rather than using an electromagnet. The switching agent would be a chemical added to the solvent. This has the potential to dramatically decrease the energy required to induce a useful change. We would lose the a lot of control; the system would act more like a switch. Any ideas how the clumped particles would react to a magnetic field compared to the reaction of a ferrofluid? Could we unclump the particles with an appropriate change to the solvent?
- "The deformability of a polymer has dramatic consequences when electrically charged species are attached along the polymer chain at a given density. The electrostatic repulsion in a long enough chain is sufficient to stretch the chain fro a random-walk configuration to that of a rigid rod, for which the end-to-end distance is proportional to the molecular weight. Polyelectrolytes, as such polymers are called, can be controlled in a fashion not possible for neutral polymers. When the interaction along the chain is screened, by the addition of some salt or the presences of other chains, the electrostatic repulsion is reduced and the polyelectrolyte chain shrinks in size. This alters fluid properties such as the viscosity." (Witten 2004, pg. 9)
- Can we exploit this shrinking to create useful motion?