2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
Swiss and Japanese engineers have created a completely soft pump for pumping dielectric fluid. It works thanks to pairs of electrodes between which an electric field is generated. Electrodes ionize some liquid particles and accelerate them, thanks to which the entire stream receives acceleration, the authors of the article in Nature say.
Almost all existing serial robots and their prototypes are made of rigid components. Even if the outer casing of the robot is made of soft material, there are usually hard control boards, batteries and electric motors inside it. Such a device cannot always be used in contact with a person, and it also makes the structure unstable to strong deformation. There is also the field of robotics, in which researchers are developing completely soft analogs of the required components. For example, soft microfluidic logic circuits, valves and even a ring generator have already been developed.
Engineers led by Herbert Shea of the Federal Polytechnic School of Lausanne have created a pump for soft robots that does not use rigid components. It consists of two layers, between which there is a liquid channel in the center. On the sides of the channel are two comb-shaped electrodes, with the protrusions disposed with an offset so that the protrusions of one electrode are located between the protrusions of the other electrode.
The pump works due to the fact that when a sufficiently large voltage is applied, the electric field strength exceeds a certain threshold and field emission begins - the emission of electrons from the electrodes. These electrons ionize some of the particles in the liquid. Due to the fact that the ions receive a negative charge, they begin to move under the action of an electric field towards the anode. These moving ions act on neighboring particles and eventually accelerate the entire stream.
Pump operation diagram
The engineers created two different pump configurations from different materials, although both use transparent polydimethylsiloxane as the casing. The differences between the options lie primarily in the material of the electrodes: a composite with carbon or silver particles. In addition, various dielectric fluids were used in the pump prototypes.
Despite the fact that the design is the same for both options, the difference in materials causes some difference in properties, both quantitative and qualitative. For example, the carbon modification allows you to select the direction of movement of the fluid only at the beginning of work, while the pump with silver electrodes allows you to switch between the two directions. In addition, silver electrodes have a much longer service life (many hours versus 15 minutes), and also create more pressure (14 kilopascals versus 7), but at the same time have a higher minimum operating voltage (5 kilovolts versus 2.5) and a longer response time …
The authors have created several prototypes based on the pumps. One of them demonstrates how fluid is pumped from one reservoir to another. Another prototype consists of a container with liquid and a "finger" of several containers. By pumping liquid from a large reservoir into a small one, the pump causes the entire structure to bend. Finally, engineers have created a heated glove that pumps fluid from a heater on the wrist to the hand.
In addition to individual soft components, completely soft autonomous robots already exist. For the first time such a device was created in 2016 by engineers from Harvard University. This robot octopus works thanks to a logic circuit based on microfluidic channels and decomposing hydrogen peroxide, which creates a gas for movement.