Energy-Efficient Four-Mode Electromagnetic Mini Valve with Single-Coil Drive: Modular Design and Application in Pneumatic Soft Actuators

In minimally invasive surgery, pneumatic soft actuators have gained significant attention due to their promising applications. Valves, which are critical components in pneumatic driving systems, typically operate in only two modes in current research. In multi-actuator systems, this limitation results in a large number of valves and a bulky driving system, which restricts the system’s portability. In this study, we report a four-mode, multi-stable, energy-efficient electromagnetic mini valve. A coil serves as the driving source. The valve has three outlets, enabling it to control up to three actuators independently. The moving components include a cylindrical magnet and a ring magnet. They are concentrically arranged and can only move along the axial direction. These magnets can realize four distinct positions based on the electromagnetic force and their mutual magnetic force. Moreover, the multi-stable design reduces energy consumption. The two cores make the magnets stable when no current is applied. The valve exhibits a shortest response time of 4.75 ms and an energy cost of 0.007 J. It can handle a maximum flow rate of 9.7 L/min at a pressure of 200 kPa, with a maximum back pressure of 100 kPa. Its energy-efficient and four-operating-mode characteristics prove its potential in pneumatic soft actuator systems. A modular design by connecting multiple mini valves reduces the number of pumps and valves, thereby lowering the overall size and weight of pneumatic driving systems. Note to Practitioners—Pneumatic soft actuators are widely used in automation systems because they are flexible and safe. However, controlling multiple actuators often needs many valves, making the system large and heavy. This work introduces a small valve with four operating modes. It can control up to three actuators by itself. The valve holds its position without continuous power, which saves energy. It also responds quickly and can deliver a high airflow. By connecting several of these valves, users can build simpler and lighter pneumatic systems. This valve is useful for portable automation devices, medical robots, and wearable systems. In the future, the valve design could be connected to smart controllers for more advanced automatic control.