Highly deformable and photoresponsive smart actuators are attracting increasing attention. Here, a high concentration of graphene is dispersed in polydimethylsiloxane (PDMS) by combining the advantages of various dispersion methods. The composite and pure PDMS layers are used to fabricate bilayer actuators with a high capacity for rapid deformation. The fabricated bilayer actuators exhibit novel and interesting properties. A bilayer actuator containing a 30 wt % graphene composite can be deflected by 7.9 mm in the horizontal direction under infrared laser irradiation. The graphene concentration in the composite influences actuator adjustment to deformation and its response speed, and the composite also exhibits superhydrophobicity. On the basis of its superhydrophobicity and large deformation capacity, the actuator made with 30 wt % graphene composite is used to construct a beluga whale soft robot. The robot can swim quickly in water at an average speed of 6 mm/s, and it can cover a distance of 30 mm in 5 s when irradiated just once with an infrared laser. Actuators fabricated with this method can be used in artificial muscle, bionic grippers, and various soft robots that require actuators with large deformation capacities.
Soft continuum robots (CRs) can be potentially applied in minimally invasive surgery due to their slender continuously deformable bodies. However, miniaturization, dexterity, and control accuracy remain as targets and challenges for medical soft CRs. In this article, we present a control strategy for a minimalist structured multisection magnetic continuum robot (MCR) to show its dexterous and accurate motion ability. The robot is embedded with two opposite axially polarized magnets. This makes it capable of deforming in a higher order curve under the influence of an external mobile magnet. This minimalist structure is suitable for submillimeter steerable microcatheters, and facilitates micromanipulation in hard-to-access region of the body. Using a Jacobian-based inverse kinematics method, the robot realizes tip position and orientation control, as well as multisection control in three dimensions with the accuracy of up to 1.30 ± 0.48 mm and 2.8 ± 1.0°. Furthermore, we showcase various medical applications of our proposed MCR for dexterous navigation, orthogonal motion, and pivoting motion. Our article aims to demonstrate dexterous and accurate motion capability of the proposed multisection magnetic soft microcatheter, which helps execute significant robotic tasks in real-world clinical applications.
Hydrogel microstructures that encapsulate cells can be assembled into tissues and have broad applications in biology and medicine. However, 3D posture control for a single arbitrary microstructure remains a challenge. A novel 3D manipulation and assembly technique based on optothermally generated bubble robots is proposed. The generation, rate of growth, and motion of a microbubble robot can be controlled by modulating the power of a laser focused on the interface between the substrate and a fluid. In addition to 2D operations, bubble robots are able to perform 3D manipulations. The 3D properties of hydrogel microstructures are adjusted arbitrarily, and convex and concave structures with different heights are designed. Furthermore, annular micromodules are assembled into 3D constructs, including tubular and concentric constructs. A variety of hydrogel microstructures of different sizes and shapes are operated and assembled in both 2D and 3D conformations by bubble robots. The manipulation and assembly methods are simple, rapid, versatile, and can be used for fabricating tissue constructs.
Flexible magnetic continuum robots (MCRs) can be fabricated in small dimensions with great manipulability as their tips can deflect under fields, without the need for complicated mechanical structures to govern control, and it helps improve operating conditions during retrograde intrarenal surgery (RIRS). However, the limited effective workspace of an electromagnet‐based magnetic navigation system (MNS) influences the practical applications. Herein, the method of steering a flexible MCR in the enlarged workspace of a common MNS for RIRS is presented. First, the field heterogeneity is parameterized to quantitatively analyze its influence on the motion of the MCR. Then, a kinematic model of the MCR is constructed, by coupling the heterogeneous‐field and Cosserat‐rod models, to predict its large deformation in the enlarged workspace with constraints. The model is validated with the maximum mean error of 0.53 ± 0.39 mm for the tip position in all the experiments. It is demonstrated that the effective workspace can be enlarged to 75% of the physical workspace. In addition, experiments in phantoms, which simulate two challenges during RIRS, are performed to prove its manipulability. This study enlarges the effective workspace of the MNS, which helps expand the practical application of the MCR.