Pumps with no moving parts
A new type of pump uses the magnetohydrodynamic effect to move conductive fluids without the need for any moving parts. With slight modifications, the pump also works as a sensor or electrical switch. Professor Wanjung Wang from Louisiana State University used the well-known principle of the magnetohydrodynamic effect to pump electrically conductive liquids through thin capillaries. His apparatus consists of a rectangular canal, both sides of which are made of a conductive material, while the top and bottom are made of an insulator covered with a permanent magnet. When current flows through the electrical conductors, the Lorentz force forces the liquid in the channel to flow. So the principle is like that of an electric motor.
Because many liquids in biology and chemistry are electrically conductive, Wang believes his pump will find a wide range of applications in medicine and biotechnology. According to his ideas, liquids with low conductivities could be mixed with suitable "carrier liquids".
The great advantages of the pump are that it has no moving parts that can cause failure due to mechanical fatigue. The channel also does not become clogged as easily, and the risk of damaging sensitive molecules is low. Finally, the manufacturing costs of the apparatus are low. In order to transport larger volumes, several units are simply bundled together.
In areas where liquids are already flowing, the pump can also act as a sensor.
The pump also has its advantages for purely technical applications. When mercury is pumped through the channel, which then closes the gap between two electrodes, it works as an electrical switch. Unlike their mechanical cousins, there are no small sparks when the contact closes, which would damage the switch over time, and the contact is almost perfect because of the liquid metal connection. Unlike transistors, Wang's switch can withstand large currents. Furthermore, there is no strong heating that wastes a lot of energy, as is the case with relays.
To drive the switch, small currents are sufficient, such as those from a computer or the sensor part of the pump.
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