Actuation Scheme Research Articles

Deep Reinforcement Learning for Flow Control Exploits Different Physics for Increasing Reynolds Number Regimes

The increase in emissions associated with aviation requires deeper research into novel sensing and flow-control strategies to obtain improved aerodynamic performances. In this context, data-driven methods are suitable for exploring new approaches to control the flow and develop more efficient strategies. Deep artificial neural networks (ANNs) used together with reinforcement learning, i.e., deep reinforcement learning (DRL), are receiving more attention due to their capabilities of controlling complex problems in multiple areas. In particular, these techniques have been recently used to solve problems related to flow control. In this work, an ANN trained through a DRL agent, coupled with the numerical solver Alya, is used to perform active flow control. The Tensorforce library was used to apply DRL to the simulated flow. Two-dimensional simulations of the flow around a cylinder were conducted and an active control based on two jets located on the walls of the cylinder was considered. By gathering information from the flow surrounding the cylinder, the ANN agent is able to learn through proximal policy optimization (PPO) effective control strategies for the jets, leading to a significant drag reduction. Furthermore, the agent needs to account for the coupled effects of the friction- and pressure-drag components, as well as the interaction between the two boundary layers on both sides of the cylinder and the wake. In the present work, a Reynolds number range beyond those previously considered was studied and compared with results obtained using classical flow-control methods. Significantly different forms of nature in the control strategies were identified by the DRL as the Reynolds number Re increased. On the one hand, for Re≤1000, the classical control strategy based on an opposition control relative to the wake oscillation was obtained. On the other hand, for Re=2000, the new strategy consisted of energization of the boundary layers and the separation area, which modulated the flow separation and reduced the drag in a fashion similar to that of the drag crisis, through a high-frequency actuation. A cross-application of agents was performed for a flow at Re=2000, obtaining similar results in terms of the drag reduction with the agents trained at Re=1000 and 2000. The fact that two different strategies yielded the same performance made us question whether this Reynolds number regime (Re=2000) belongs to a transition towards a nature-different flow, which would only admits a high-frequency actuation strategy to obtain the drag reduction. At the same time, this finding allows for the application of ANNs trained at lower Reynolds numbers, but are comparable in nature, saving computational resources.

Magnetic Actuation of a Dynamically Reconfigurable Microswarm for Enhanced Ultrasound Imaging Contrast

Microrobotic swarms offer great promise in performing targeted delivery tasks with environmental adaptability. One of the significant challenges to apply microswarm for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in vivo</i> applications is medical imaging-based localization. In this article, we propose an optimized actuation strategy to enhance the ultrasound imaging contrast of a reconfigurable colloidal microswarm. A dynamic ultrasound contrast of the microswarm is observed. It depends on the coordination between the frequency of applied magnetic field and the temporal resolution of ultrasound imaging. Taking advantage of the dynamic contrast, optimal driven frequency ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$f_{\text{op}}$</tex-math></inline-formula> ) is analyzed to obtain an enhanced ultrasound contrast of microswarms at different depths, which is experimentally validated at imaging depths of 3–7 cm. Based on the modeling and experimental results, pattern transformation of the microswarm is performed to further enhance the ultrasound contrast. The change of the imaging contrast during pattern transformation is experimentally investigated and analyzed, demonstrating a good agreement with the analytical results. Moreover, the microswarm is localized <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ex vivo</i> at depths of 3.4–6.5 cm, and the minimal dose of nanoparticles is reduced due to the pattern transformation-enhanced imaging contrast. The reversible pattern transformation also provides morphological adaptability. A microswarm can navigate and simultaneously exhibit reversible pattern transformation in a narrowed channel. The optimized strategy of enhancing the ultrasound contrast of the colloidal microswarm provides a potential approach for utilizing microrobotic swarms in medical-imaging-guided <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in vivo</i> tasks with a real-time localization capability.

Reconfigurable network structure with tunable multiple deformation modes: Mechanical designs, theoretical predictions, and experimental demonstrations

Reconfigurable network structure with tunable multiple deformation modes exhibits promising applications in functional electromagnetic devices, frequency-reconfigurable antennas, flexible electronic devices, and robots with multiple motion modes due to its capability to realize multiple working characteristics in one device or system. In most previous studies on reconfigurable network structures with large deformation, researchers focus on tuning the deformation and mechanical properties for a specific deformation mode of the network structure. Therefore, designs for reconfigurable network structures to achieve multiple deformation modes and large deformation still remain a challenge. The inverse design of the reconfigurable network structure with desired mechanical responses under some specific external actuations is difficult due to the lack of theoretical models to describe the finite deformation of network structures actuated by external fields. This paper introduces a mechanical design strategy for the reconfigurable network structure to achieve a large deformation (over 45%) and multiple mechanical responses under the electrothermal actuation, including the uniform or non-uniform shrinkage and expansion, shearing, and bending deformation modes. Theoretical models for this reconfigurable network structure are developed to predict these unique mechanical responses and inversely design the reconfigurable network structure for the desired deformation modes in a facilitating method. The accuracy of the designed reconfigurable network structure is validated by the corresponding finite element analyses (FEAs) and experiments qualitatively and quantitatively. In accordance with these theoretical models, the deformed configuration and analytic solutions for some critical mechanical quantities, such as the electrothermally actuated effective strain for shrinkage, expansion and shearing deformation modes, and the bending angle for bending deformation modes, are obtained. The electrothermally actuated deformation of network structures can be tuned by the value of the normalized geometrical parameter d/t1 and the electrothermal actuation strategy. Furthermore, demonstrative experiments and FE simulations illustrate that multiple deformation modes can be achieved in the same network structure through the individual actuation strategy. This work provides guidelines from the aspects of theoretical predictions, FEAs, and experiments for future designs of the reconfigurable network structures to achieve desired mechanical responses.

4D printing Light-Driven soft actuators based on Liquid-Vapor phase transition composites with inherent sensing capability

Soft robots capable of responding to different actuation schemes are flourishing due to the appealing advantages of being highly flexible and adaptive to complex environments. However, it remains challenging to produce untether soft actuators that can sense their own motions. Herein, a novel photo-responsive liquid–vapor phase transition composite with integrated actuating and sensing performances is proposed. The composite is operated based on the principle that piezocapacitive sensing and liquid–vapor phase transition are caused by the photothermal effect of the embedded graphene plate. The composite exhibits superior and tunable optically responsive and self-sensing properties. As a proof of concept, the muscle-like actuator with effective actuating and real-time sensing feedback functions is produced. Furthermore, several “Janus” bilayer untethered actuators are fabricated via 3D printing, which can achieve a variety of light-driven programmed locomotion, such as bending, grasping, and crawling. This work holds great promise for designing and fabricating soft robots with integrated self-sensing capacity.

Performance Analysis of 4-DOF RPRR Robot Manipulator Actuation Strategy for Pick and Place Application in Healthcare Environment

Direct and indirect physical contact of humans and objects become the main medium of transmissible diseases such as COVID-19. Some strategies have been proposed to mitigate the risks of infections by minimizing physical contact, such as using robotics technology. Tele-robotics is one of the sub-fields in robotics that aims to implement physical surrogates for monitoring and controlling robots from remote distances, either autonomous, semi-autonomous, or manually guided. This paper discusses experimental research for evaluating the performance of a 4-DOF robot manipulator for pick and place tasks on small medical objects, such as test tubes in table-top scenarios. The robot manipulator is designed as an RPRR manipulator and is equipped with a gripper attached to its end-effector. Inverse kinematics and trajectory planning methods have been successfully implemented in real-time. The inverse kinematic method utilizes a pseudo-inverse Jacobian solver, and the trajectory generation utilizes a sigmoid function. The performance analysis results show that pick and place missions have been demonstrated with minimum tolerable position error, which is not more than 3.5 mm. The robot manipulator can satisfy high precision during repetitive experiments and maintain its accuracy in picking and placing standard test tubes from one rack to another within its working space. The smooth trajectories of the end-effector are achieved by implementing the sigmoid function. Thus, it satisfies the requirement for handling objects with minimum vibrations even during the actuation process with maximum speed.

Laminar boundary layer forcing with active surface deformations

The use of active surface deformations as an actuation strategy has been largely overlooked in the flow control literature. In this work, we investigate how active surface deformations applied over a range of frequencies and amplitudes affect a laminar boundary layer. We find that the strategy is capable of producing both high- and low-speed motions. These motions appear well-suited for flow control, especially at the lowest actuation frequencies.

Cable-Driven Parallel Robot Actuators: State of the Art and Novel Servo-Winch Concept

Cable-Driven Parallel Robots (CDPRs) use cables arranged in a parallel fashion to manipulate an end-effector (EE). They are functionally similar to several cranes that automatically collaborate in handling a shared payload. Thus, CDPRs share several types of equipment with cranes, such as winches, hoists, and pulleys. On the other hand, since CDPRs rely on model-based automatic controllers for their operations, standard crane equipment may severely limit their performance. In particular, to achieve reasonably accurate feedback control of the EE pose during the process, the length of the cable inside the workspace of the robot should be known. Cable length is usually inferred by measuring winch angular displacement, but this operation is simple and accurate only if the winch transmission ratio is constant. This problem called for the design of novel actuation schemes for CDPRs; in this paper, we analyze the existing architectures of so-called servo-winches (i.e., servo-actuators which employ a rotational motor and have a constant transmission ratio), and we propose a novel servo-winch concept and compare the state-of-the-art architectures with our design in terms of pros and cons, design requirements, and applications.

A Review on the Development of Pneumatic Artificial Muscle Actuators: Force Model and Application

Pneumatic artificial muscles (PAMs) are soft and flexible linear pneumatic actuators which produce human muscle like actuation. Due to these properties, the muscle actuators have an adaptable compliance for various robotic platforms as well as medical applications. While a variety of possible actuation schemes are present, there is still a need for the development of a soft actuator that is very light-weight, compact, and flexible with high power-to-weight ratio. To achieve this, the development of the PAM actuators has become an interesting topic for many researchers. In this review, the development of the different kinds of PAM available to date are presented along with manufacturing process and the operating principle. The various force models for artificial muscle presented in the literature are broadly reviewed with the constraints. Furthermore, the applications of PAM are included and classified based on the fields of biorobotics, medicine, and industry, along with advanced medical instrumentation. Finally, the needful improvements in terms of the dynamics of the muscle are discussed for the precise control of the PAMs as per the requirements for the applications. This review will be helpful for researchers working in the field of robotics and for designers to develop new type of artificial muscle depending on the applications.

Soft Fluidic Actuator for Locomotion in Multi-Phase Environments

This letter presents the design, development, and experimental assessment of a soft fluidic actuator that can enable locomotion in a variety of aquatic and terrestrial environments. Most actuation strategies for amphibious locomotion rely on rigid, fast moving components to generate thrust and tractive forces. Our prototype, comprising soft materials, and relying on simple motion planning and control strategies, demonstrates two gaits, that we employ for locomotion in two vastly different scenarios, underwater swimming and moving on granular terrain with varying levels of water content. By adjusting its internal pressure, the actuator dynamically varies its stiffness and shape, and transitions between wheel and soft paddle form. Experimental results of locomotion in controlled laboratory conditions serve as proof-of-concept for the proposed actuator's efficacy. Using two different motion patterns and control schemes, we show that this prototype achieves both thrust and tractive forces.

The kinematics and design for isotropy of six-dof 3-CCC parallel mechanisms of general geometry and arbitrary actuation schemes

Parallel mechanisms (PMs) of the 3-CCC class exhibit many attractive features, such as decoupled motion, degenerated singularity, simple forward-kinematics relations and high dexterity, making them promising in many applications. However, in order to simplify the analysis, existing research mainly focuses on its several subclasses, leading to drawbacks such as limited choices of the architecture parameters, excessive link interference and limited orientation workspace. In this paper, a uniform formulation is proposed for the kinematics analysis of the whole class of 3-CCC PMs of general geometry and arbitrary actuation schemes; the geometric meanings of the relevant quantities are revealed, significantly simplifying the analysis of 3-CCC PMs. Next, the design for isotropy of the whole class of 3-CCC PMs is investigated, yielding a large set of isotropic designs, including a subset admitting a continuous isotropy locus; several typical layouts with attractive features are proposed thereafter, including designs admitting unlimited rotation about a fixed or an adjustable direction. The results above can also be applied to six-dof PMs with more sophisticated topologies, as long as they are kinematically equivalent to 3-CCC PMs.

A dynamically reprogrammable surface with self-evolving shape morphing.

Dynamic shape-morphing soft materials systems are ubiquitous in living organisms; they are also of rapidly increasing relevance to emerging technologies in soft machines1-3, flexible electronics4,5 and smart medicines6. Soft matter equipped with responsive components can switch between designed shapes or structures, but cannot support the types of dynamic morphing capabilities needed to reproduce natural, continuous processes of interest for many applications7-24. Challenges lie in the development of schemes to reprogram target shapes after fabrication, especially when complexities associated with the operating physics and disturbances from the environment can stop the use of deterministic theoretical models to guide inverse design and control strategies25-30. Here we present a mechanical metasurface constructed from a matrix of filamentary metal traces, driven by reprogrammable, distributed Lorentz forces that follow from the passage of electrical currents in the presence of a static magnetic field. The resulting system demonstrates complex, dynamic morphing capabilities with response times within 0.1 second. Implementing an in situ stereo-imaging feedback strategy with a digitally controlled actuation scheme guided by an optimization algorithm yields surfaces that can follow a self-evolving inverse design to morph into a wide range of three-dimensional target shapes with high precision, including an ability to morph against extrinsic or intrinsic perturbations. These concepts support a data-driven approach to the design of dynamic soft matter, with many unique characteristics.

Development of Two-Step Exhaust Rebreathing for a Low-NOx Light-Duty Gasoline Compression Ignition Engine

The global automotive industry is undergoing a significant transition as battery electric vehicles enter the market and diesel sales decline. It is widely recognized that internal combustion engines (ICE) will be needed for transport for years to come; however, demands on ICE fuel efficiency, emissions, cost, and performance are extremely challenging. Gasoline compression ignition (GCI) is one approach for achieving the demanding efficiency and emissions targets. A key technology enabler for GCI is partially-premixed, compression ignition (PPCI) combustion, which involves two high-pressure, late fuel injections during the compression stroke. Both NOx and smoke emissions are greatly reduced relative to diesel, and this reduces the aftertreatment (AT) requirements significantly. For robust low-load and cold operation, a two-step valvetrain system is used for exhaust rebreathing (RB). Exhaust rebreathing involves the reinduction of hot exhaust gases into the cylinder during a second exhaust lift event during the intake stroke to help promote autoignition. The amount of exhaust rebreathing is controlled by exhaust backpressure, created by the vanes on the variable nozzle turbine (VNT) turbocharger. Because of the higher cycle temperatures during rebreathing, exhaust HC and CO may be significantly reduced, while combustion robustness and stability also improve. Importantly, exhaust rebreathing significantly increases exhaust temperatures in order to maintain active catalysis in the AT system for ultra-low tailpipe emissions. To achieve these benefits, it is important to optimize the rebreathe valve lift profile and develop an RB ON→OFF (mode switch) strategy that is easy to implement and control, without engine torque fluctuation. In this study, an engine model was developed using GT-Suite to conduct steady-state and transient engine simulations of the rebreathing process, followed by engine tests. The investigation was conducted in four parts. In part 1, various rebreathe lift profiles were simulated. The system performance was evaluated based on in-cylinder temperature, exhaust temperature, and pumping work. The results were compared with alternative variable valve actuation (VVA) strategies such as early exhaust valve closing (EEVC), negative valve overlap (NVO), positive valve overlap (PVO). In part 2, steady-state simulations were conducted to determine an appropriate engine load range for mode switching (exhaust rebreathing ON/OFF and vice-versa). The limits for both in-cylinder temperature and exhaust gas temperature, as well as the external exhaust gas recirculation (EGR) delivery potential were set as the criteria for load selection. In part 3, transient simulations were conducted to evaluate various mode switch strategies. For RB OFF, the cooled external EGR was utilized with the goal to maintain exhaust gas dilution during mode switches for low NOx emissions. The most promising mode-switch strategies produced negligible torque fluctuation during the mode switch. Finally, in part 4, engine tests were conducted, using the developed RB valve lift profile, at various low-load operating conditions. The mode switch experiments correlated well with the simulation results. The tests demonstrated the simplicity and robustness of the exhaust rebreathing approach. A robust engine response, low CNL, high exhaust gas temperature, and low engine out emissions were achieved in the low load region.

Flow-reduced double valve actuation for improving the dynamic performance of electro-hydraulic servo drive

Due to the negative correlation between the frequency response and the rated flow of the servo valve, there remains challenge to achieve high dynamic response of large-flow servo valve-controlled hydraulic systems under extreme operating conditions. Although the effective bandwidth of such system can be extended via various control methods, the inherent performance limit of hardware limits further improvement of the system dynamic response. In this paper, a flow-reduced double valve actuation strategy is proposed to improve the performance of electro-hydraulic servo drives. By reducing the actually used flow, the frequency response of the servo valve is enhanced due to the decreased hydraulic spring force and transient flow force acting on the spool. Two flow-reduced servo valves are adopted in parallel to meet large flow along with the improved dynamic performance. Simulation research is conducted and a servo valve-controlled shaking table with a specially designed valve block is used for experimental validation. Simulation and experimental results prove that the proposed strategy possesses better dynamic performance than the conventional single valve actuation.

Nanobots-based advancement in targeted drug delivery and imaging: An update.

Manipulation and targeted navigation of nanobots in complex biological conditions can be achieved by chemical reactions, by applying external forces, and via motile cells. Several studies have applied fuel-based and fuel-free propulsion mechanisms for nanobots movements in environmental sciences and robotics. However, their applications in biomedical sciences are still in the budding phase. Therefore, the current review introduces the fundamentals of different propulsion strategies based on the advantageous features of applied nanomaterials or cellular components. Furthermore, the recent developments reported in various literatures on next-generation nanobots, such as Xenobots with applications of in-vitro and in-vivo drug delivery and imaging were also explored in detail. The challenges and the future prospects are also highlighted with corresponding advantages and limitations of nanobots in biomedical applications. This review concludes that with ever booming research enthusiasm in this field and increasing multidisciplinary cooperation, micro-/nanorobots with intelligence and multifunctions will emerge in the near future, which would have a profound impact on the treatment of diseases.

Ultrasound‐Controlled Swarmbots Under Physiological Flow Conditions

AbstractNavigation of microrobots in living vasculatures is essential in realizing targeted drug delivery and advancing non‐invasive surgeries. Acoustically‐controlled “swarmbots” are developed based on the self‐assembly of clinically‐approved microbubbles (MBs). Ultrasound is noninvasive, penetrates deeply into the human body, and is well‐developed in clinical settings. This propulsion strategy relies on two forces: the primary radiation force and the secondary Bjerknes force. Upon ultrasound activation, the MBs self‐assemble into microswarms, which migrate toward and anchor at the containing vessel's wall. A second transducer, which produces an acoustic field parallel to the channel, propels the swarms along the wall. Noting that human arteries have a blood flow 5–19 cm s−1, powerful features of cross‐ and upstream swarmbot navigation are demonstrated against physiologically‐relevant flow rates that reach 16.7 cm s−1. Additionally, controlled navigation of swarmbots is shown within mice blood and under pulsatile flow conditions of 100 beats per minute (bpm); an adult human heart at rest executes between 60 and 100 bpm. This capability represents a much‐needed pathway for advancing preclinical research.

Design and Fabrication of a Tunable Optofluidic Microlens Driven by an Encircled Thermo-Pneumatic Actuator.

This paper presents the design, simulation, fabrication, assembly, and testing of a miniature thermo-pneumatic optofluidic lens. The device comprises two separate zones for air heating and fluid pressing on a flexible membrane. A buried three-dimensional spiral microchannel connects the two zones without pumps or valves. The three-dimensional microfluidic structure is realized using a high-resolution three-dimensional printing technique. Multi-physics finite element simulations are introduced to assess the optimized air chamber design and the low-temperature gradient of the optical liquid. The tunable lens can be operated using a direct-current power supply. The temperature change with time is measured using an infrared thermal imager. The focal length ranges from 5 to 23 mm under a maximum voltage of 6 V. Because of the small size and robust actuation scheme, the device can potentially be integrated into miniature micro-optics devices for the fine-tuning of focal lengths.

Microrobotic swarms for selective embolization.

Inspired by the collective intelligence in natural swarms, microrobotic agents have been controlled to form artificial swarms for targeted drug delivery, enhanced imaging, and hyperthermia. Different from these well-investigated tasks, this work aims to develop microrobotic swarms for embolization, which is a clinical technique used to block blood vessels for treating tumors, fistulas, and arteriovenous malformations. Magnetic particle swarms were formed for selective embolization to address the low selectivity of the present embolization technique that is prone to cause complications such as stroke and blindness. We established an analytical model that describes the relationships between fluid viscosity, flow rate, branching angle, magnetic field strength, and swarm integrity, based on which an actuation strategy was developed to maintain the swarm integrity inside a targeted region under fluidic flow conditions. Experiments in microfluidic channels, ex vivo tissues, and in vivo porcine kidneys validated the efficacy of the proposed strategy for selective embolization.

Finite Element Modeling of Internally Actuated Triangular Lattice and Its Variants for Modular Active Cell Robots (MACROs)

Modular Active Cell Robots (MACROs) is an approach for modular robot hardware that leverages simple components such as actuators and compliant joints to make large deformable robotic structures. In this letter, we consider the planar triangular lattice and its sparser variants as the candidate mesh topologies for MACROs. Through Finite Element (FE) simulations, we quantify the deformations obtained for different choices of edges being actuated in the MACRO mesh. Further, we use this data to identify optimal actuation strategies for a target deformation. We demonstrate a trade-off between passive stiffness and actuation energy and thereafter, we refine the triangular lattice by removing edges to reduce the actuation energy without a significant reduction in stiffness. We also identify the refined meshes optimal for desired specifications.

Hydraulic Detrusor for Artificial Bladder Active Voiding.

The gold standard treatment for bladder cancer is radical cystectomy that implies bladder removal coupled to urinary diversions. Despite the serious complications and the impossibility of controlled active voiding, bladder substitution with artificial systems is a challenge and cannot represent a real option, yet. In this article, we present hydraulic artificial detrusor prototypes to control and drive the voiding of an artificial bladder (AB). These prototypes rely on two actuator designs (origami and bellows) based either on negative or positive operating pressure, to be combined with an AB structure. Based on the bladder geometry and size, we optimized the actuators in terms of contraction/expansion performances, minimizing the liquid volume required for actuation and exploring different actuator arrangements to maximize the voiding efficiency. To operate the actuators, an ad hoc electrohydraulic circuit was developed for transferring liquid between the actuators and a reservoir, both of them intended to be implanted. The AB, actuators, and reservoir were fabricated with biocompatible flexible thermoplastic materials by a heat-sealing process. We assessed the voiding efficiency with benchtop experiments by varying the actuator type and arrangement at different simulated patient positions (horizontal, 45° tilted, and vertical) to identify the optimal configuration and actuation strategy. The most efficient solution relies on two bellows actuators anchored to the AB. This artificial detrusor design resulted in a voiding efficiency of about 99%, 99%, and 89%, in the vertical, 45° tilted, and horizontal positions, respectively. The relative voiding time was reduced by about 17, 24, and 55 s compared with the unactuated bladder.

2D‐Material‐Integrated Micromachines: Competing Propulsion Strategy and Enhanced Bacterial Disinfection

2Dtransition-metal-dichalcogenidematerials, such as molybdenum disulfide (MoS2 ) have received immense interest owing to their remarkable structure-endowed electronic, catalytic, and mechanical properties for applications in optoelectronics, energy storage, and wearable devices. However, 2D materials have been rarely explored in the field of micro/nanomachines, motors, and robots. Here, MoS2 with anatase TiO2 is successfully integrated into an original one-side-open hollow micromachine, which demonstrates increased light absorption of TiO2 -based micromachines to the visible region and the first observed motion acceleration in response to ionic media. Both experimentation and theoretical analysis suggest the unique type-II bandgap alignment of MoS2 /TiO2 heterojunction that accounts for the observed unique locomotion owing to a competing propulsion mechanism. Furthermore, by leveraging the chemical properties of MoS2 /TiO2 , the micromachines achieve sunlight-powered water disinfection with 99.999%Escherichia colilysed in anhour. This research suggests abundant opportunities offered by 2D materials in the creation of a new class of micro/nanomachines and robots.