Additive manufacturing, or 3D printing, offers a way to craft miniaturized devices that contain multiple materials with new capabilities, and that are designed on demand for more personalized applications.
A new miniature pump — compact, valveless, and operated magnetically — demonstrates the capabilities of devices manufactured by 3D printing. Measuring 1 centimeter in volume, the pump was fabricated in 75 minutes in a single process using multiple materials that cost less than $3.89 per unit. It can move both liquids and gases using less power and experiencing less clogging than standard manufactured pumps of this size.
The pumps, each slightly less than the diameter of a dime, are shaped as small cylinders crowned by a membrane. On top of the membrane is the fluid chamber with two valveless ports at the top to attach tubes. The researchers printed the pump in two ways using Nylon 12 as the structural material in both. In the first pump, a magnet is press-fitted into the structure of the enclosing piston. With the second monolithic pump, the researchers used Nylon 12 embedded with neodymium magnet (NdFeB) microparticles to create the pump’s magnetic core. Nylon 12 is a structural material that can easily absorb large amounts of the magnetic particles and is sturdy enough to hold still the NdFeB microparticles during the initial magnetization, which makes it possible to create strong permanent magnets.
The pump is driven by an outside rotating magnet that interacts with the internal magnet to move the piston and deform the membrane, propelling the liquid or gas from one port to the other. The piston is only constrained by the membrane, so it can move in multiple ways at the same time when activated by the external magnet. Since it is magnetically driven, the new device is more portable than pneumatic pumps, which need to be physically coupled to an outside source of pressurized fluid.
The researchers were able to increase the new pump’s stroke capacity beyond that of a pump classically manufactured in silicon by altering printing methods to make a more deformable membrane while keeping a more rigid piston body — all using the same Nylon 12 material.