Project #73: Ferrofluid Pump with Only Fluid Moving Parts

Public Invention has defined over 75 project ideas. Some of these have been gifted to us by readers like you who are willing to donate an idea to the whole world by publishing it; many were thought of by myself. Some ideas are very well-developed, others are just a paragraph.

One of the better ideas which would be commercially valuable if developed is the idea of making a Ferrofluid Pump with no moving parts (except for fluid). A pump that has no moving mechanical parts is very valuable because it may never wear out. Additionally, mechanical parts are expensive to miniaturize to a microscopic level. Yet most applications of ferrofluid motion involve either in-vivo medicine of “lab-on-a-chip” ideas or the cooling of microchips, all of which call for tiny little pumps. Public Invention does not seek patents or royalties on any of its inventions (though we will of course take legal action against anyone who fraudulently attempts to patent an idea we have given to the world by publishing.) The repo for this idea is here.

A pump that has only fluidic moving parts is likely manufacturable on a tiny micro- or nano-scale. A tiny pump could be made into a chip and pump fluid to the part of the chip generating heat which must be dumped and then into a heat sink or a heat exchanger. This would provide very efficient cooling of chips.

Moreover, if the moving parts are fluidic, it becomes possible that the entire pump can be made “soft”, that is, out of deformable components. Such a “soft pump” would be idea of in vivo applications within the human body. Of course, one does not normally pump ferrofluid into the body itself; but being able to route a moving fluid would allow, for example, the inflation of small balloons to close or open blood vessels. Pumped ferrofluid could be used to pump blood or other body fluids within the body reliably.

In this idea, the only moving parts are two blobs of water. The idea (which is described in detail in the link above), is to use a blob of water as a free piston. Because water does not mix with oil (most ferrofluid is nanoscale balls of iron suspended in ferrofluid), such a blob of water if contained in a channel with ferrofluid on either end will stay together and can be indirectly driven by magnetic fields acting on ferrofluid next to it.

One researcher has created a solid-state ferrofluid pumping system previously, but it was very inefficient and produced low flows. This idea would be expected to be as efficient as a water pump, and would certainly deserve a peer-reviewed publication if it is demonstrated to work. Here’s a teaser image of how it would work (refer to the technical paper for an actual explanation):

We would like to form an invention team around this idea, but we need one core volunteer who is willing to try to build it. This requires some knowledge of driving electromagnets from a microcontroller, the kind of skill that many readers of Make magazine have, for example. It might involve some CAD design for 3D printing (though I have already designed an initial draft 3D printable test apparatus at the github repo.) Of course, as the head invention coach of Public Invention, I would work closely with you to help design and build and measure the pumping efficiency and flow.

I personally believe this would make a good Master’s thesis in mechanical engineering or biomedical engineering, or a really excellent senior capstone project. If your are interested in volunteering to make this, please contact me at

–Robert L. Read, PhD

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