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

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

Tandem actuation of legged locomotion and grasping manipulation in soft robots using magnetic fields

Untethered soft robots have the potential to impact a variety of applications, particularly if they are capable of controllable locomotion and dexterous manipulation. Magnetic fields can provide humansafe, contactless actuation, opening the gates to applications in confined spaces - for example, in minimally invasive surgery. To translate these concepts into reality, soft robots are being developed with different capabilities, such as functional components to achieve motion and object manipulation. This paper investigates the tandem actuation of two separate functions (locomotion and grasping) through multi-legged soft robots with grippers, actuated by magnetic fields. The locomotion and grasping functions are activated separately by exploiting the difference in the response of the soft robots to the magnitude, frequency and direction of the actuating magnetic field. Two robots capable of performing controllable straight and turning motions are demonstrated: a millipede-inspired robot with legs moving in a rhythmic pattern, and a hexapod robot with six magnetic legs following an alternating tripod gait. Two types of grippers are developed: one inspired by prehensile tails and another similar to flowers or jellyfish. The various components are fabricated using a composite of silicone rubber with magnetic powder, and analyzed using quasi-static models and experimental results. Fully untethered locomotion of the robots and independent gripper actuation are illustrated through experiments. The maneuverability of the robots is proven through teleoperated steering experiments where the robots navigate through the workspace while avoiding obstacles. The ability of the robots to manipulate objects by operating in tandem with the grippers is demonstrated through multiple experiments, including pick-and-place tasks where the robots grasp and release cargo at specific locations when triggered using magnetic fields. (C) 2020 The Authors. Published by Elsevier Ltd

Advanced medical micro-robotics for early diagnosis and therapeutic interventions

Recent technological advances in micro-robotics have demonstrated their immense potential for biomedical applications. Emerging micro-robots have versatile sensing systems, flexible locomotion and dexterous manipulation capabilities that can significantly contribute to the healthcare system. Despite the appreciated and tangible benefits of medical micro-robotics, many challenges still remain. Here, we review the major challenges, current trends and significant achievements for developing versatile and intelligent micro-robotics with a focus on applications in early diagnosis and therapeutic interventions. We also consider some recent emerging micro-robotic technologies that employ synthetic biology to support a new generation of living micro-robots. We expect to inspire future development of micro-robots toward clinical translation by identifying the roadblocks that need to be overcome

Magnetic motion control and planning of untethered soft grippers using ultrasound image feedback

Soft miniaturized untethered grippers can be used to manipulate and transport biological material in unstructured and tortuous environments. Previous studies on control of soft miniaturized grippers employed cameras and optical images as a feedback modality. However, the use of cameras might be unsuitable for localizing miniaturized agents that navigate within the human body. In this paper, we demonstrate the wireless magnetic motion control and planning of soft untethered grippers using feedback extracted from B-mode ultrasound images. Results show that our system employing ultrasound images can be used to control the miniaturized grippers with an average tracking error of 0.4±0.13 mm without payload and 0.36±0.05 mm when the agent performs a transportation task with a payload. The proposed ultrasound feedback magnetic control system demonstrates the ability to control miniaturized grippers in situations where visual feedback cannot be provided via cameras

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

Advanced medical micro-robotics for early diagnosis and therapeutic interventions

Recent technological advances in micro-robotics have demonstrated their immense potential for biomedical applications. Emerging micro-robots have versatile sensing systems, flexible locomotion and dexterous manipulation capabilities that can significantly contribute to the healthcare system. Despite the appreciated and tangible benefits of medical micro-robotics, many challenges still remain. Here, we review the major challenges, current trends and significant achievements for developing versatile and intelligent micro-robotics with a focus on applications in early diagnosis and therapeutic interventions. We also consider some recent emerging micro-robotic technologies that employ synthetic biology to support a new generation of living micro-robots. We expect to inspire future development of micro-robots toward clinical translation by identifying the roadblocks that need to be overcome

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