MINIATURE ROBOTIC SYSTEM
Bioinspired Multilegged Soft Millirobot
In a study published in Nature Communications, the team of Prof. SHEN Yajing has developed a tiny, soft robot with caterpillar-like legs capable of carrying heavy loads and adapting to a variety of environments inside the body. Small, soft robots are gaining attention around the world for their potential uses in biomedicine. However, being able to control the robot’s movements inside the body can be challenging.
In the present study, researchers designed a miniature robot with multiple legs that can move efficiently on the inner surfaces of the body. Made of polydimethylsiloxane embedded with magnetic particles, the robot can be remotely controlled by applying an electromagnetic force. It can move in both a flap propulsion pattern—where it uses its front feet to flap forward—and in an inverted pendulum pattern, by swinging its body and standing on left and right feet alternately.
Magnetic Spray Transforms Inanimate Objects Into Millirobots
Millirobots that can adapt to unstructured environments, operate in confined spaces, and interact with a diverse range of objects would be desirable for exploration and biomedical applications. The continued development of millirobots, however, requires simple and scalable fabrication techniques. Here, the team of Prof. SHEN Yajing propose a minimalist approach to construct millirobots by coating inanimate objects with a composited agglutinate magnetic spray. Researchers enable a variety of one-dimensional (1D), 2D, or 3D objects to be covered with a thin magnetically drivable film (~100 to 250 micrometers in thickness). The film is thin enough to preserve the original size, morphology, and structure of the objects while providing actuation of up to hundreds of times its own weight. Under the actuation of a magnetic field, the designed millirobots are able to demonstrate a range of locomotive abilities: crawling, walking, and rolling. Moreover, researchers can reprogram and disintegrate the magnetic film on millirobots on demand. Finally, they leverage these abilities to demonstrate biomedical applications, including catheter navigation and drug delivery.
Soft Magnetic Skin For Super-resolution Tactile Sensing
Human skin can sense subtle changes of both normal and shear forces and perceive stimuli with finer resolution than the average spacing between mechanoreceptors. By contrast, existing tactile sensors for robotic applications are inferior, lacking accurate force decoupling and proper spatial resolution at the same time. Here, the team of Prof. SHEN Yajing presents a soft tactile sensor with self-decoupling and super-resolution abilities by designing a sinusoidally magnetized flexible film (with the thickness ~0.5 millimeters), whose deformation can be detected by a Hall sensor according to the change of magnetic flux densities under external forces. The sensor can accurately measure the normal force and the shear force (demonstrated in one dimension) with a single unit and achieve a 60-fold super-resolved accuracy enhanced by deep learning. By mounting our sensor at the fingertip of a robotic gripper, they show that robots can accomplish challenging tasks such as stably grasping fragile objects under external disturbance and threading a needle via teleoperation. This research provides new insight into tactile sensor design and could be beneficial to various applications in robotics field, such as adaptive grasping, dexterous manipulation, and human-robot interaction.
Self-adaptive Propulsion of Ray Sperms And Bioinspired Swimming Robot
It is generally agreed that sperms "swim" by beating or rotating their soft tails. However, the research team led by Prof. SHEN Yajing has discovered that ray sperms move by rotating both the tail and the head.
The team further investigated the motion pattern and demonstrated it with a robot. Their study has expanded the knowledge on the microorganisms' motion and provided inspiration for robot engineering design.
Reconfigurable Milli-scale Cellular Robots
Modular robot that can reconfigure architectures and functions has advantages in unpredicted environment and task. However, the construction of modular robot at small-scale remains a challenge since the lack of reliable docking and detaching strategies. Here, the research team led by Prof. SHEN Yajing report the concept of milli-scale cellular robot (mCEBOT) achieved by the heterogeneous assembly of two types of units (short and long units). Under the magnetic field, the proposed mCEBOT units can not only selectively assemble (e.g., end-by-end and side-by-side) into diverse morphologies corresponding to the unstructured environments, but also configure multi-modes motion behaviors (e.g., slipping, rolling, walking and climbing) based on the on-site task requirements. They demonstrate its adaptive mobility from narrow space to high barrier to wetting surface, and its potential applications in hanging target taking and environment exploration. The concept of mCEBOT offers new opportunities for robot design, and will broaden the field of modular robot in both miniaturization and functionalization.
Millirobot for Upstream Swimming in Blood Vessel
Untethered small robots with multiple functions show considerable potential as next-generation catheter-free systems for biomedical applications. However, owing to dynamic blood flow, even effective upstream swimming in blood vessels remains a challenge for the robot, let alone performing medical tasks. The team of Prof. SHEN Yajing presents an untethered millirobot with a streamlined shape that integrates the engine, delivery, and biopsy modules. Based on the proposed spiral-rolling strategy, this robot can move upstream at a record-breaking speed of ~14 mm/s against a blood phantom flow of 136 mm/s. Moreover, benefiting from the bioinspired self-sealing orifice and easy-open auto-closed biopsy needle sheath, this robot facilitates several biomedical tasks in blood vessels, such as in vivo drug delivery, tissue and liquid biopsy, and cell transportation in rabbit arteries. This study will benefit the development of wireless millirobots for controllable, minimally invasive, highly integrated, and multifunctional endovascular interventions and will inspire new designs of miniature devices for biomedical applications.