A Contactless and Biocompatible Approach for 3D Active Microrobotic Targeted Drug Delivery

As robotic tools are becoming a fundamental part of present day surgical interventions, microrobotic surgery is steadily approaching clinically-relevant scenarios. In particular, minimally invasive microrobotic targeted drug deliveries are reaching the grasp of the current state-of-the-art technology. However, clinically-relevant issues, such as lack of biocompatibility and dexterity, complicate the clinical application of the results obtained in controlled environments. Consequently, in this work we present a proof-of-concept fully contactless and biocompatible approach for active targeted delivery of a drug-model. In order to achieve full biocompatiblity and contacless actuation, magnetic fields are used for motion control, ultrasound is used for imaging, and induction heating is used for active drug-model release. The presented system is validated in a three-dimensional phantom of human vessels, performing ten trials that mimic targeted drug delivery using a drug-coated microrobot. The system is capable of closed-loop motion control with average velocity and positioning error of 0.3 mm/s and 0.4 mm, respectively. Overall, our findings suggest that the presented approach could augment the current capabilities of microrobotic tools, helping the development of clinically-relevant approaches for active in-vivo targeted drug delivery

Autonomous planning and control of soft untethered grippers in unstructured environments

The use of small, maneuverable, untethered and reconfigurable robots could provide numerous advantages in various micromanipulation tasks. Examples include microassembly, pick-and-place of fragile microobjects for lab-on-a-chip applications, assisted hatching for in-vitro fertilization and minimally invasive surgery. This study assesses the potential of soft untethered magnetic grippers as alternatives or complements to conventional tethered or rigid micromanipulators. We demonstrate closed-loop control of untethered grippers and automated pick-and-place of biological material on porcine tissue in an unstructured environment. We also demonstrate the ability of the soft grippers to recognize and sort non-biological micro-scale objects. The fully autonomous nature of the experiments is made possible by the integration of planning and decision-making algorithms, as well as by closed-loop temperature and electromagnetic motion control. The grippers are capable of completing pick-and-place tasks of biological material at an average velocity of 1.8±0.71 mm/s and a drop-off error of 0.62±0.22 mm. Color-sensitive sorting of three micro-scale objects is completed at a velocity of 1.21±0.68 mm/s and a drop-off error of 0.85±0.41 mm. Our findings suggest that improved autonomous un-tethered grippers could augment the capabilities of current soft-robotic instruments especially in advanced tasks involving manipulation

Design, characterization and control of thermally-responsive and magnetically-actuated micro-grippers at the air-water interface

The design and control of untethered microrobotic agents has drawn a lot of attention in recent years. This technology truly possesses the potential to revolutionize the field of minimally invasive surgery and microassembly. However, miniaturization and reliable actuation of micro-fabricated grippers are still challenging at sub-millimeter scale. In this study, we design, manufacture, characterize, and control four similarly-structured semi-rigid thermoresponsive micro-grippers. Furthermore, we develop a closed loop-control algorithm to demonstrate and compare the performance of the said grippers when moving in hard-to-reach and unpredictable environments. Finally, we analyze the grasping characteristics of three of the presented designs. Overall, not only does the study demonstrate motion control in unstructured dynamic environments-at velocities up to 3.4, 2.9, 3.3, and 1 body-lengths/s with 980, 750, 250, and 100 μm-sized grippers, respectively-but it also aims to provide quantitative data and considerations to help a targeted design of magnetically-controlled thin micro-grippers

Control of untethered soft grippers for pick-and-place tasks

In order to handle complex tasks in hard-toreach environments, small-scale robots have to possess suitable dexterous and untethered control capabilities. The fabrication and manipulation of soft small- scale grippers complying to these requirements is now made possible by advances in material science and robotics. In this paper, we use soft small-scale grippers to demonstrate pick-and-place tasks. The precise remote control is obtained by altering both the magnetic field gradient and the temperature in the workspace. This allows us to regulate the position and grasping configuration of the soft thermally-responsive hydrogel-nanoparticle composite magnetic grippers. The magnetic closed-loop control achieves precise localization with an average region-of-convergence of the gripper of 0.12±0.05 mm. The micro-sized payload can be placed with a positioning error of 0.57±0.33 mm. The soft grippers move with an average velocity of 0.72±0.13 mm/s without a micro-sized payload, and at 1.09±0.07 mm/s with a micro-sized payloa

The EU Center of Excellence for Exascale in Solid Earth (ChEESE): Implementation, results, and roadmap for the second phase

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Elastic wave dispersion in layered media with suture joints: influence of structural hierarchy and viscoelasticity

Suture joints contribute to the exceptional combination of stiffness, strength, toughness and efficient load bearing and transmission of many biological structures like the cranium or ammonite fossil shells. However, their role in the attenuation of vibrations and effect on dynamic loads is less clear. Moreover, the self-similar hierarchical geometry often associated with suture joints renders its treatment with standard numerical approaches computationally prohibitive. To address this problem, this paper investigates the dynamic response of periodic layered media with suture joints using an analytical approach based on material homogenization. A general trapezoidal suture geometry is considered together with the fundamental ingredients of hierarchy and viscoelasticity. The Spectral Element Method and Bloch theorem are used to derive the dispersion relation and band diagram of the system, including propagating and evanescent dispersion modes. A strong influence of the suture morphology and material properties emerges, and the analysis reveals an important advantage of adding hierarchy, i.e. the possibility of simultaneously obtaining wider bandgaps and their shift to higher frequencies. A synergy between hierarchy and structure is also observed, providing superior levels of wave attenuation. These findings suggest a possible design concept for bioinspired devices with efficient and tailorable wave attenuation properties

Precise Model-Free Spline-Based Approach for Magnetic Field Mapping

Untethered magnetic manipulation has found applications in a rapidly increasing number of fields, ranging from minimally invasive surgery to assembly of industrial microelectromechanical systems. Despite this relevance, present-day literature on precise magnetic mapping is sparse, especially for magnetic fields affected by external disturbances. In this letter, we address this deficiency by introducing a model-free mapping technique. Remarkably, the presented spline-based approach is capable of addressing the presence of inhomogeneous static disturbances and the mapping of nonazimuthally symmetric electromagnets. This work is validated with the mapping of nine metal-core electromagnets in the presence of inhomogeneous static disturbances. A grid of 5120 measurements is collected by a custom-programed robotic arm and used for mapping. The values predicted by the approach are compared against 3430 independent field measurements with an R-2 value of 0.9884 and maximum relative errors of 7%. Overall, this spline-based approach provides a flexible technique for the precise mapping of electromagnetic fields and gradients even when, for reasons regarding coil shape or disturbances, the electromagnetic field does not present any axial symmetry

Design of an Electromagnetic Setup for Independent Three-Dimensional Control of Pairs of Identical and Nonidentical Microrobots

Independent control ofmicrorobots is a cardinal challenge for manipulation at micro/nano scale. In this paper, we design and assemble an electromagnetic setup to overcome some of the major obstacles in the independent control of microrobots. The demanding magnetic requirements are met by the presented experimental testbed that is able to produce magnetic fields and gradients of, respectively, 160 mT and 3.6 T/m at the center of the workspace. Through the design process of this testbed, we analyze the importance of design parameters and derive a quantitative analysis of the requirements for the dissipation of the generated heat. Further, we present and develop the model and software infrastructure, capable of running at 25 Hz, necessary for independent control of multiple microrobots. We also introduce two novel techniques for current-minimizing mapping of the desired forces into currents at the electromagnet. Finally, the capabilities of the setup are demonstrated through independent control of two, both identical and nonidentical, soft-magnetic microspheres in three-dimensional space-with average root mean square errors of 102 mu m and peak velocities of up to 331 mu m/s

Evaluation of an electromagnetic system with haptic feedback for control of untethered, soft grippers affected by disturbances

Current wireless, small-scale robots have restricted manipulation capabilities, and limited intuitive tools to control their motion. This paper presents a novel teleoperation system with haptic feedback for the control of untethered soft grippers. The system is able to move and open/close the grippers by regulating the magnetic field and temperature in the workspace. Users can intuitively control the grippers using a grounded haptic interface, that is also capable of providing compelling force feedback information as the gripper interacts with the environment. The magnetic closed-loop control algorithm is designed starting from a Finite Element Model analysis. The electromagnetic model used is validated by a measurement of the magnetic field with a resolution of 0.1 mT and sampling rate of 6.8×106 samples/m2. The system shows an accuracy in positioning the gripper of 0.08 mm at a velocity of 0.81 mm/s. The robustness of the control and tracking algorithms are tested by spraying the workspace with water drops that cause glares and related disturbances of up to 0.41 mm

Steering and Control of Miniaturized Untethered Soft Magnetic Grippers With Haptic Assistance

International audienceUntethered miniature robotics have recently shown promising results in several scenarios at the microscale, such as targeted drug delivery, microassembly, and biopsy procedures. However, the vast majority of these small-scale robots have very limited manipulation capabilities, and none of the steering systems currently available enable humans to intuitively and effectively control dexterous miniaturized robots in a remote environment. In this paper, we present an innovative micro teleop-eration system with haptic assistance for the intuitive steering and control of miniaturized self-folding soft magnetic grippers in 2-dimensional space. The soft grippers can be wirelessly positioned using weak magnetic fields and opened/closed by changing their temperature. An image-guided algorithm tracks the position of the controlled miniaturized gripper in the remote environment. A haptic interface provides the human operator with compelling haptic sensations about the interaction between the gripper and the environment, as well as enabling the operator to intuitively control the target position and grasping configuration of the gripper. Finally, magnetic and thermal control systems regulate the position and grasping configuration of the gripper. The viability of the proposed approach is demonstrated through two experiments involving twenty-six human subjects. Providing haptic stimuli elicited statistically significant improvements in the performance of the considered navigation and micromanipulation tasks. Note to Practitioners—The ability to accurately and intuitively control the motion of miniaturized grippers in remote environments can open new exciting possibilities in the fields of minimally-invasive surgery, micromanipulation, biopsy, and drug delivery. This article presents a micro teleoperation system with haptic assistance through which a clinician can easily control the motion and open/close capability of miniaturized wireless soft grippers. It introduces the underlying autonomous magnetic and thermal control systems, their interconnection with the master haptic interface, and an extensive evaluation in two real-world C. Pacchierotti is affiliated with CNRS at Irisa and Inria Rennes, France. F. Ongaro, F. van den Brink, and S. Misra are affiliated with the Surgical The authors also thank Dr. Stefano Scheggi for his help in setting up the tracking system. scenarios: following of a predetermined trajectory, and pick-and-place of a microscopic object