A Bistable Four-Working-States Electromagnetic Mini Valve Based on Flexible Magnets for Pneumatic Soft Actuators

Electromagnetic mini valves have attracted widespread interest recently. However, traditional ones usually have two working states and necessitate continuous energy input. To solve these issues, we developed a bistable electromagnetic compact valve (R9×44 mm) with four working states based on three-dimensional-printed moving magnets. For obtaining four working states, each moving magnet with a fixed-beam structure is actuated independently. To keep working without requiring energy, we present a magnetic-force-based bistable mechanism involving iron cores, moving magnets, and fixed magnets. Since the valve's closing and opening are kept by an intrinsic magnetic force between magnets, it requires an instantaneous current (0.008 s) to switch working modes. Furthermore, we added a 1 mm thick magnet to the moving magnet to enhance the valve's performance. Consequently, its pressure and flow rate dramatically rose from 1.0 to 30.0 kPa and 0.18 to 11.2 L/min, respectively. Its energy consumption and response time are 0.16 J and 0.008 s. Due to its four working states and bistable function, this research is demonstrated to reduce the number of valves and energy required in pneumatic systems. In the future, we will focus on its applications in invasive surgery equipment and bionic devices.