Fang Lu, Pengfei Han, Guofang Gong, Huayong Yang, Dong Han
Sensors and Actuators: A. Physical 2024
As core components of microfluidic and wearable pneumatic electronic systems, mini valves are attracting a growing intellectual interest. However, most existing mini valve exhibit either excessive energy consumption or limited flow rate and holding pressure. To address these issues, this study proposes an energy-saving mini valve with large flow rate and high holding pressure. The implementation of electromagnetic bistable structure allows the valve to remain open or closed without energy consumption. In contrast to the small and intricate flow channels seen in conventional mini valves, the straight-through flow channel design with reduced flow resistance improves its flow rate properties. And the pressure resistance characteristics are enhanced by the use of permanent magnetic attraction for sealing. Furthermore, the valve is driven by a single coil to switch between two steady states, resulting in a more compact structure. We have developed valve prototypes with diameters of 10 mm and 6 mm. Performance evaluation tests have shown that it sustains a holding pressure as high as 100 kPa and a flow rate of 1.5 L/min (@ 3 kPa), while only expending an energy of 0.37 J during switch transitions. Given these attributes, this valve demonstrates significant potential for integration within wearable pneumatic electronic systems.
Pengfei Han, Qing Cao, Jingjia Zhu, Guofang Gong, Huayong Yang, Dong Han
Submitted to Sensors and Actuators: A. Physical
Recently, there has been active research in developing robotic catheter systems for treating cardiac arrhythmia. Nevertheless, state-of-the-art studies on ablation catheters typically exhibit a force-position coupling phenomenon and a low control accuracy without sensors. To solve these issues, a hybrid pneumatic and tendon-driven soft ablation catheter (R4.5×50 mm) using a sensor-free force-position decoupled control approach was proposed in this article. To realize decoupled control, the catheter’s force and position are actuated by air pressure and tendons, respectively. This allows the two operating modes, outputting force and moving tip position, to be controlled independently. To manipulate its force and position more precisely, this research suggested a neural network-based control methodology. The disparity between the theoretical model and the actual condition is eliminated by training the experiment data. Compared with the traditional model-based control technologies, the force and position mean error decreases from 0.02 N to 0.013 N and 1.43 mm to 0.59 mm, respectively. The bandwidth is approximately 0.33 Hz. This research has been demonstrated to decrease control errors without sensors. Future work will focus on perfecting the control framework to enable the catheter to be used in the cardiac ablation procedure.
Jingjia Zhu, Pengfei Han, Chao Qi, Guofang Gong, Huayong Yang, Tadahiko shinshi, Dong Han
Sensors and Actuators: A. Physical 2024
Electromagnetic mini valves have attracted great interest in medical devices for their excellent performance and high integration. In state-of-the-art research, most mini valves have only two working states, while certain ones featuring three to four working states necessitate multiple driving sources. To solve these problems, a novel tristable electromagnetic mini valve with three stable working states achieved by a single coil was proposed. The actuation mechanism of this mini valve mainly comprises a cylindrical magnet (CM) and a ring magnet (RM) coaxially arranged. In the absence of current through the coil, the stability of the magnets is upheld by their mutual repulsion and the attraction of the iron core. Upon modifying both the magnitude and orientation of the current, one of the magnets traverses from one terminus to another each time. The two magnets are either stationary at the start point or the endpoint. Thereby, four position relationships are formed, three of which are stable. The minimum response time and energy consumption are 3.75 ms and 0.013 J, respectively. The working pressure of the valve ranges from 0 to 200 kPa. The maximum flow rate and back pressure reach 10.5 L/min and 180 kPa, respectively. A tristable design contributes to lower energy consumption, and the three-working-state function actuated by a single coil facilitates a diminution in the size of the mini valve. Consequently, a diminished quantity of valves is realized for multiple degree-of-freedom pneumatic actuator control, which promotes the miniaturization of the whole system. The dimensions and performance of the proposed mini valve substantiate its potential in pneumatic medical devices.
Yuning Jiang, Pengfei Han, Jingjia Zhu, Guofang Gong, Huayong Yang, Dong Han
Submitted to Soft Robotics
The present research delves into the realm of multi-state mini valves, a subject of considerable intrigue due to their integrative capabilities within pneumatic actuator systems. Although it has been widely recognized that mini valves are used in numerous applications, the majority of current mini valves have three or fewer working states. Furthermore, those uncommon valves capable of operating in four working states exhibit limitations, including the necessity for multiple driving sources and elevated operational energy requirements. Addressing these impediments, our study introduces an innovative electromagnetic valve design (R7.5×30 mm) that facilitates the switching among four discrete operational states under the governance of a singular electrical power source. This valve attains four stable operational states by coordinating interactions between the upper and lower iron cores, a ring magnet, and a cylindrical magnet. The valve maintains a leakage rate that is nearly zero under pressures up to 250 kPa. Furthermore, rapid transitions between states are achievable by momentarily electrifying the valve's coils, with peak transition response time and energy expenditure being only 7.50 ms and 0.540 J, respectively. Leveraging this quad-state valve mechanism, the study unveils the precise control over the locomotion and directional maneuvers of a pneumatic soft inchworm-like walker, culminating in a propulsion velocity of 0.072 BL/s. This achievement underscores the latent potential of multi-state valves in the miniaturization of pneumatic systems.
Pengfei Han, Fang Lu, Guofang Gong, Huayong Yang, Dong Han
IEEE Transactions on Industrial Electronics 2023
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 3D-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 kPa to 30.0 kPa and 0.18 L/min 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.
Pengfei Han, Fang Lu, Guofang Gong, Huayong Yang, Dong Han
Smart Materials and Structures 2023
Electromagnetic mini valves for controlling pneumatic soft actuators are attracting widespread interest in recent years. However, it is known that the traditional electromagnetic valves on the millimeter scale generally have three or fewer working states, and their moving parts are usually permanent magnets with a special shape that needs expensive manufacturing. To overcome these problems, this study aims to develop a mini valve with four working states based on flexible magnets at a low fabrication cost. We take full advantage of low-cost 3D-printed magnets’ physical and magnetic properties and improve their performance through origami-inspired magnetization. A fixed-beam-structure flexible magnet is proposed to control this valve via deformation so that valve’s two sides can be driven independently, resulting in four working states. Compared with conventional sintered magnets, 3D printing magnets can be manufactured quickly and affordably. Due to the proposed valves’ more operating states than the state-of-art three-way ones, they are proven to reduce the number of small control elements in the pneumatic system. The maximum flow rate of the valve at 5 kPa air pressure was 0.81 L/min at the power consumption of 20 W. This mini valve has the potential in controlling multi-degree-of-freedom pneumatic soft actuators.