Soft Solenoid Valve Using Liquid Metal Coil

• Ryan Weiss, Computer Engineering, University of Delaware

• Nathan Lazarus, Electrical and Computer Engineering, University of Delaware

Soft robotics is a developing field focused on creating robots that are mostly or entirely flexible, enabling their use in compact and hazardous environments. This research aimed to develop a solenoid valve using a Gallium–Indium eutectic (EGaIn) liquid metal alloy and magnets within a silicon shell. This approach enhances the potential for fully soft robots and more intricate soft robotic designs. While liquid metal has been previously utilized in soft robotics, forming it into complex shapes, such as the coil of an electromagnet, remains challenging.

This method involved creating a coil using silicon tubing and super glue, ensuring a strong bond with the silicon structure. This coil was then filled with EGaIn to complete the electromagnet. The flow channel was fabricated by 3D printing a negative mold, which was removed after pouring and setting the silicon. This process yielded a thin “U” shaped channel, into which silicon tubes were inserted and secured with silicon glue. A unified structure was created by placing the flow channel in a 3D printed mold, positioning the coil on top, and filling the remaining space with silicon. Afterwards, copper wires were inserted into the coil ends as termination points. Securing the components with super glue allowed for  testing with a peristaltic pump. Testing showed that by running a current through the coil, the magnet would be able to create enough pressure to stop the flow of liquid through the channel and have flow resume after the current was turned off. Thus, a functional soft solenoid valve was successfully created.

This development signifies a significant advancement in the field of soft robotics, demonstrating the feasibility of integrating liquid metal alloys in creating flexible, complex electromagnetic devices.