Tianlu Wang

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Wang

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Tianlu

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0000-0001-9972-7821

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Publications1 - 10 of 14

Wireless Miniature Magnetic Phase-Change Soft Actuators
Tang, Yichao; Li, Mingtong; Wang, Tianlu; et al. (2022)
Advanced Materials
Wireless miniature soft actuators are promising for various potential high-impact applications in medical, robotic grippers, and artificial muscles. However, these miniature soft actuators are currently constrained by a small output force and low work capacity. To address such challenges, a miniature magnetic phase-change soft composite actuator is reported. This soft actuator exhibits an expanding deformation and enables up to a 70 N output force and 175.2 J g(-1) work capacity under remote magnetic radio frequency heating, which are 10(6)-10(7) times that of traditional magnetic soft actuators. To demonstrate its capabilities, a wireless soft robotic device is first designed that can withstand 0.24 m s(-1) fluid flows in an artery phantom. By integrating it with a thermally-responsive shape-memory polymer and bistable metamaterial sleeve, a wireless reversible bistable stent is designed toward future potential angioplasty applications. Moreover, it can additionally locomote inside and jump out of granular media. At last, the phase-change actuator can realize programmable bending deformations when a specifically designed magnetization profile is encoded, enhancing its shape-programming capability. Such a miniature soft actuator provides an approach to enhance the mechanical output and versatility of magnetic soft robots and devices, extending their medical and other potential applications.
Advanced Miniature Soft Robotic Systems
Wang, Tianlu (2022)
Miniature soft robots have shown unprecedented safe access in the hard-to-reach complex regions of nature, given their small dimensions and compliance by design. These machines are thus promising for novel biomedical applications, environmental stewardship, and beyond. While various miniature soft robots have been demonstrated, high-performance miniature soft robotic systems for task-oriented locomotions and functions have not been properly achieved. Particularly, the development of systems for task-oriented locomotions and functions is insufficient. Moreover, the improvement of these systems for fast and energy-efficient locomotions and multiple functions is unavailable. These challenges restrain the potential real-world translations of this unique robotic group. To this end, task-oriented locomotions and functions were addressed by properly developing the miniature soft robotic systems, including robot bodies and relevant systems. First, we addressed the challenge of designing bistable anchoring devices in tubular structures and the corresponding reliable medical imaging-based control system. While the stable anchoring state enables the robot to withstand the peristaltic forces in tubular structures for local functions, the stable relaxation state allows the manipulation of robot locomotion. Moreover, effective robot tracking utilizing medical imaging is necessary to deploy medical devices safely. In this study, the magnetic soft millirobot and actuation system were chosen, given their wireless controllability and the realization of the bistable states. Moreover, ultrasound imaging, known for its non-ionization principle, portability, and real-time imaging capability, was integrated into the control system for the robot's robust tracking and closed-loop manipulation. The effectiveness of the system has been validated experimentally. The proposed tracking method could also be extrapolated to other miniature soft robots for potential medical functions. While focusing on tubular structures, we further explored the design of millirobotic structures and their accompanying spatial actuation system for the regions with dynamic flow. Such a new intervention paradigm is critical given the various devastating diseases around distal neural arteries and the difficult conventional catheter-based access. The wireless soft millirobot was designed to be stent-shaped for its adaptability, low fluidic drag feature, and maneuverability in the lumen with the flow. Supported by controlled interactions with the solid boundaries, various locomotion capabilities were enabled and evaluated, such as the retrievable shape-adaptive locomotion for varying lumen diameters, self-anchoring to withstand the flow, curved route, and branch traversing. On top of the design, two potential medical functions were incorporated, i.e., flow diversion and on-demand local drug delivery by the remote heating of the SMP-based foldable structures. This new distal intervention paradigm has been compared with the conventional approach in the phantoms emulating the distal arterial regions and showed advantages in accessibility, interaction forces, delivered drug dosage, and adjustability. Based on the knowledge of developing task-oriented miniature soft systems, we then investigated how to further improve the performances for fast and energy-efficient locomotions and multiple functions. Fast and energy-efficient undulatory propulsion, one of the most widely spread locomotion modes, is critical for long-term operations. Although numerous studies have focused on the inertial flow regime, the intermediate flow regime was not well studied due to the lack of effective robotic tools. Therefore, we designed a class of untethered undulatory milliswimmers and magnetic actuation systems with the advantage of wireless operation without the negative effect of driving cables on hydrodynamics. By experimentally optimizing the body stiffness distributions k and actuation signals, we have emulated critical features of morphology, body kinematics, and wake flow patterns as larval zebrafish at both dimension and time scales using the novel robotic platform. The effect of k was systematically studied, and results revealed that combining high frequency and uniform k is energy-beneficial. On top of the knowledge, the shape memory polymer (SMP)-integrated wireless swimmer capable of adjusting k on the fly was further evaluated and confirmed the conclusions. Besides its impact on the autonomous underwater robot, this study could inspire wireless medical devices for targeted cargo delivery. While maintaining the high-performance propulsion, we explored the mechanism for multi-functionalities, which could be beneficial for various real-world tasks, in the final part of this thesis. Inspired by jellyfish's energy-efficient locomotion and contactless object manipulation, we developed a jellyfish-like robotic platform via an optimized synergy of electrohydraulic actuators and a hybrid structure comprising both rigid and soft components. As a result, the robot could propel fast, efficiently, and silently, which could accomplish possible safe interactions with the underwater species. Moreover, multiple functions were realized, such as contact-based and contactless object manipulation, fluidic mixing, shape adaptation, and steering. On top of a single robot, multiple agents could be individually controlled and form a team to enhance object manipulation. Finally, a wireless prototype, with all control electronics and batteries onboard, was developed and tested outdoors, indicating the potential feasibility of such compact miniature robotic systems for future field operations.
Magnetically assisted soft milli-tools for occluded lumen morphology detection
Yan, Yingbo; Wang, Tianlu; Zhang, Rongjing; et al. (2023)
Science Advances
Methodologies based on intravascular imaging have revolutionized the diagnosis and treatment of endovascular diseases. However, current methods are limited in detecting, i.e., visualizing and crossing, complicated occluded vessels. Therefore, we propose a miniature soft tool comprising a magnet-assisted active deformation segment (ADS) and a fluid drag-driven segment (FDS) to visualize and cross the occlusions with various morphologies. First, via soft-bodied deformation and interaction, the ADS could visualize the structure details of partial occlusions with features as small as 0.5 millimeters. Then, by leveraging the fluidic drag from the pulsatile flow, the FDS could automatically detect an entry point selectively from severe occlusions with complicated microchannels whose diameters are down to 0.2 millimeters. The functions have been validated in both biologically relevant phantoms and organs ex vivo. This soft tool could help enhance the efficacy of minimally invasive medicine for the diagnosis and treatment of occlusions in various circulatory systems.
Synthetic Data-Assisted Miniature Medical Robot Navigation via Ultrasound Imaging
Wang, Chunxiang; Wang, Tianlu; Sitti, Metin (2025)
IEEE/ASME Transactions on Mechatronics
Wireless miniature robots are promising for minimally invasive biomedical applications. Effective tracking and navigation are essential for their safe deployment, but challenges persist in medical imaging and robot control, especially in localizing the robot in complex imaging scenes. Deep learning, though powerful for object identification, requires large supervised datasets, limiting its clinical applications due to the difficulty and cost of acquiring realistic data. Furthermore, miniature robots frequently exit the field of view of imaging systems, hindering continuous observation. Here, we present a framework for real-time magnetic navigation of wireless miniature robots using ultrasound imaging, leveraging synthetic data generation for deep learning-based detection. First, artificially generated synthetic data is combined with real data from synthetic materials to train a neural network capable of detecting versatile robots in real tissues. Then, a robotic system is developed to automatically track the robot with an ultrasound probe during magnetic actuation in tortuous lumens. With 85% less human-labeled data within synthetic materials, our approach effectively detects versatile robots in ex-vivo tissues, reducing data scarcity, imbalance, and manual labeling burdens. Demonstrations of automatic robot navigation through tortuous lumens in complex ultrasound scenes validate its effectiveness, enhancing the safe applicability of miniature medical robots in complex environments.
Heterogeneous multiple soft millirobots in three-dimensional lumens
Wang, Chunxiang; Wang, Tianlu; Li, Mingtong; et al. (2024)
Science Advances
Miniature soft robots offer opportunities for safe and physically adaptive medical interventions in hard-to-reach regions. Deploying multiple robots could further enhance the efficacy and multifunctionality of these operations. However, multirobot deployment in physiologically relevant three-dimensional (3D) tubular structures is limited by the lack of effective mechanisms for independent control of miniature magnetic soft robots. This work presents a framework leveraging the shape-adaptive robotic design and heterogeneous resistance from robot-lumen interactions to enable magnetic multirobot control. We first compute influence and actuation regions to quantify robot movement. Subsequently, a path planning algorithm generates the trajectory of a permanent magnet for multirobot navigation in 3D lumens. Last, robots are controlled individually in multilayer lumen networks under medical imaging. Demonstrations of multilocation cargo delivery and flow diversion manifest their potential to enhance biomedical functions. This framework offers a solution to multirobot actuation benefiting applications across different miniature robotic devices in complex environments.
Soft-robotic ciliated epidermis for reconfigurable coordinated fluid manipulation
Ren, Ziyu; Zhang, Mingchao; Song, Shanyuan; et al. (2022)
Science Advances
The fluid manipulation capabilities of current artificial cilia are severely handicapped by the inability to reconfigure near-surface flow on various static or dynamically deforming three-dimensional (3D) substrates. To overcome this challenge, we propose an electrically driven soft-robotic ciliated epidermis with multiple independently controlled polypyrrole bending actuators. The beating kinematics and the coordination of multiple actuators can be dynamically reconfigured to control the strength and direction of fluid transportation. We achieve fluid transportation along and perpendicular to the beating directions of the actuator arrays, and toward or away from the substrate. The ciliated epidermises are bendable and stretchable and can be deployed on various static or dynamically deforming 3D surfaces. They enable previously difficult to obtain fluid manipulation functionalities, such as transporting fluid in tubular structures or enhancing fluid transportation near dynamically bending and expanding surfaces.
The ART of LLM Refinement: Ask, Refine, and Trust
Shridhar, Kumar; Sinha, Koustuv; Cohen, Andrew; et al. (2023)
arXiv
In recent years, Large Language Models (LLMs) have demonstrated remarkable generative abilities, but can they judge the quality of their own generations? A popular concept, referred to as self-refinement, postulates that LLMs can detect and correct the errors in their generations when asked to do so. However, recent empirical evidence points in the opposite direction, suggesting that LLMs often struggle to accurately identify errors when reasoning is involved. To address this, we propose a reasoning with refinement objective called ART: Ask, Refine, and Trust, which asks necessary questions to decide when an LLM should refine its output, and either affirm or withhold trust in its refinement by ranking the refinement and the initial prediction. On two multistep reasoning tasks of mathematical word problems (GSM8K) and question answering (StrategyQA), ART achieves a performance gain of +5 points over self-refinement baselines, while using a much smaller model as the decision maker. We also demonstrate the benefit of using smaller models to make refinement decisions as a cost-effective alternative to fine-tuning a larger model.
A versatile jellyfish-like robotic platform for effective underwater propulsion and manipulation
Wang, Tianlu; Joo, Hyeong-Joon; Song, Shanyuan; et al. (2023)
Science Advances
Underwater devices are critical for environmental applications. However, existing prototypes typically use bulky, noisy actuators and limited configurations. Consequently, they struggle to ensure noise-free and gentle interactions with underwater species when realizing practical functions. Therefore, we developed a jellyfish-like robotic platform enabled by a synergy of electrohydraulic actuators and a hybrid structure of rigid and soft components. Our 16-cm-diameter noise-free prototype could control the fluid flow to propel while manipulating objects to be kept beneath its body without physical contact, thereby enabling safer interactions. Its against-gravity speed was up to 6.1 cm/s, substantially quicker than other examples in literature, while only requiring a low input power of around 100 mW. Moreover, using the platform, we demonstrated contact-based object manipulation, fluidic mixing, shape adaptation, steering, wireless swimming, and cooperation of two to three robots. This study introduces a versatile jellyfish-like robotic platform with a wide range of functions for diverse applications.
Ultrasound-Guided Wireless Tubular Robotic Anchoring System
Wang, Tianlu; Hu, Wenqi; Ren, Ziyu; et al. (2020)
IEEE Robotics and Automation Letters
Untethered miniature robots have significant potential and promise in diverse minimally invasive medical applications inside the human body. For drug delivery and physical contraception applications inside tubular structures, it is desirable to have a miniature anchoring robot with self-locking mechanism at a target tubular region. Moreover, the behavior of this robot should be tracked and feedback-controlled by a medical imaging-based system. While such a system is unavailable, we report a reversible untethered anchoring robot design based on remote magnetic actuation. The current robot prototype's dimension is 7.5 mm in diameter, 17.8 mm in length, and made of soft polyurethane elastomer, photopolymer, and two tiny permanent magnets. Its relaxation and anchoring states can be maintained in a stable manner without supplying any control and actuation input. To control the robot's locomotion, we implement a two-dimensional (2D) ultrasound imaging-based tracking and control system, which automatically sweeps locally and updates the robot's position. With such a system, we demonstrate that the robot can be controlled to follow a pre-defined 1D path with the maximal position error of 0.53 ± 0.05 mm inside a tubular phantom, where the reversible anchoring could be achieved under the monitoring of ultrasound imaging.
Hybrid Contact Detection and Force Estimation during Compliant Manipulation
Wang, Tianlu (2021)

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Tianlu Wang

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