Magnetic Microrobots for Biomedical Applications

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "E:Engineering and Technology".

Deadline for manuscript submissions: closed (10 July 2023) | Viewed by 17266

Special Issue Editors

Department of Electronic Engineering, Ocean University of China, Qingdao 266000, China
Interests: micro-nano manufacturing; magnetic microrobotics; MEMS/NEMS devices
Department of Mechanical & Electrical Engineering, Xiamen University, Xiamen 361101, China
Interests: microrobotics; microfabrication; microsensors; microfluidics

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Guest Editor
Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
Interests: dynamic systems and control; robotics (AI, soft, bionic, medical, collaborative, and assistive); smart machinery and manufacturing; mechatronics; magnetic recording; data storage systems
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Guest Editor
Department of Mechanical Engineering, Vanderbilt University, Nashville, TN 37235, USA
Interests: Miniature robotics; soft robots; medical robotics; biomedical devices; and magnetic actuation.
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

With the rapid development of micro/nanofabrication technology, various multifunctional microrobots have recently emerged and hold great potential in the biomedical field. The term “microrobots” refers to a controllable agent with a size in the range of just micrometers. Because of their small scale, these miniature robots can access complex and narrow regions of the human body in a minimally invasive manner, for example in the vasculature, brain, eye, articular cavity, gastrointestinal tract, etc. However, owing to their small size, actuators that can be used for the in vivo propelling of microrobots at the micro scale are still lacking. Currently, a viable option for steering such a microrobot is through external energy transfer. In particular, using magnetic fields for microrobot actuation is the most versatile option for biomedical applications because of their advantages: insensitivity to biological substances, no direct contact, remote-control ability and precise positioning ability. In biomedical fields, magnetic microrobots have the potential to perform various tasks, such as minimally invasive surgery, targeted drug/cell delivery, cell manipulation, biopsy, imaging-guided surgery, intracellular measurement, and antibacterial applications. The aim of this Special Issue of Micromachines, is to present recent advances in magnetic microrobots for biomedical applications, including, but not limited to, microrobot design and development, control theories for microrobots, magnetic actuation system design and in vivo imaging of microrobots.

Dr. Junyang Li
Dr. Tao Luo
Prof. Dr. Jen-Yuan (James) Chang
Dr. Xiaoguang Dong
Guest Editors

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Keywords

  • microfabrication
  • microrobotics
  • magnetic actuation
  • biomedical applications

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Published Papers (9 papers)

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Research

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14 pages, 3113 KiB  
Article
Navigation and Control of Motion Modes with Soft Microrobots at Low Reynolds Numbers
by Gokhan Kararsiz, Yasin Cagatay Duygu, Zhengguang Wang, Louis William Rogowski, Sung Jea Park and Min Jun Kim
Micromachines 2023, 14(6), 1209; https://doi.org/10.3390/mi14061209 - 7 Jun 2023
Cited by 4 | Viewed by 1612
Abstract
This study investigates the motion characteristics of soft alginate microrobots in complex fluidic environments utilizing wireless magnetic fields for actuation. The aim is to explore the diverse motion modes that arise due to shear forces in viscoelastic fluids by employing snowman-shaped microrobots. Polyacrylamide [...] Read more.
This study investigates the motion characteristics of soft alginate microrobots in complex fluidic environments utilizing wireless magnetic fields for actuation. The aim is to explore the diverse motion modes that arise due to shear forces in viscoelastic fluids by employing snowman-shaped microrobots. Polyacrylamide (PAA), a water-soluble polymer, is used to create a dynamic environment with non-Newtonian fluid properties. Microrobots are fabricated via an extrusion-based microcentrifugal droplet method, successfully demonstrating the feasibility of both wiggling and tumbling motions. Specifically, the wiggling motion primarily results from the interplay between the viscoelastic fluid environment and the microrobots’ non-uniform magnetization. Furthermore, it is discovered that the viscoelasticity properties of the fluid influence the motion behavior of the microrobots, leading to non-uniform behavior in complex environments for microrobot swarms. Through velocity analysis, valuable insights into the relationship between applied magnetic fields and motion characteristics are obtained, facilitating a more realistic understanding of surface locomotion for targeted drug delivery purposes while accounting for swarm dynamics and non-uniform behavior. Full article
(This article belongs to the Special Issue Magnetic Microrobots for Biomedical Applications)
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15 pages, 15204 KiB  
Article
A Fast Soft Continuum Catheter Robot Manufacturing Strategy Based on Heterogeneous Modular Magnetic Units
by Tieshan Zhang, Gen Li, Xiong Yang, Hao Ren, Dong Guo, Hong Wang, Ki Chan, Zhou Ye, Tianshuo Zhao, Chengfei Zhang, Wanfeng Shang and Yajing Shen
Micromachines 2023, 14(5), 911; https://doi.org/10.3390/mi14050911 - 23 Apr 2023
Viewed by 1937
Abstract
Developing small-scale continuum catheter robots with inherent soft bodies and high adaptability to different environments holds great promise for biomedical engineering applications. However, current reports indicate that these robots meet challenges when it comes to quick and flexible fabrication with simpler processing components. [...] Read more.
Developing small-scale continuum catheter robots with inherent soft bodies and high adaptability to different environments holds great promise for biomedical engineering applications. However, current reports indicate that these robots meet challenges when it comes to quick and flexible fabrication with simpler processing components. Herein, we report a millimeter-scale magnetic-polymer-based modular continuum catheter robot (MMCCR) that is capable of performing multifarious bending through a fast and general modular fabrication strategy. By preprogramming the magnetization directions of two types of simple magnetic units, the assembled MMCCR with three discrete magnetic sections could be transformed from a single curvature pose with a large tender angle to a multicurvature S shape in the applied magnetic field. Through static and dynamic deformation analyses for MMCCRs, high adaptability to varied confined spaces can be predicted. By employing a bronchial tree phantom, the proposed MMCCRs demonstrated their capability to adaptively access different channels, even those with challenging geometries that require large bending angles and unique S-shaped contours. The proposed MMCCRs and the fabrication strategy shine new light on the design and development of magnetic continuum robots with versatile deformation styles, which would further enrich broad potential applications in biomedical engineering. Full article
(This article belongs to the Special Issue Magnetic Microrobots for Biomedical Applications)
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15 pages, 7400 KiB  
Article
Identification of the Position of a Tethered Delivery Catheter to Retrieve an Untethered Magnetic Robot in a Vascular Environment
by Serim Lee, Nahyun Kim, Junhyoung Kwon and Gunhee Jang
Micromachines 2023, 14(4), 724; https://doi.org/10.3390/mi14040724 - 24 Mar 2023
Viewed by 1306
Abstract
In this paper, we propose a method of identifying the position of a tethered delivery catheter in a vascular environment, recombining an untethered magnetic robot (UMR) to the tethered delivery catheter, and safely retrieving them from the vascular environment in an endovascular intervention [...] Read more.
In this paper, we propose a method of identifying the position of a tethered delivery catheter in a vascular environment, recombining an untethered magnetic robot (UMR) to the tethered delivery catheter, and safely retrieving them from the vascular environment in an endovascular intervention by utilizing a separable and recombinable magnetic robot (SRMR) and a magnetic navigation system (MNS). From images of a blood vessel and a tethered delivery catheter taken from two different angles, we developed a method of extracting the position of the delivery catheter in the blood vessel by introducing dimensionless cross-sectional coordinates. Then, we propose a retrieval method for the UMR by using the magnetic force considering the delivery catheter’s position, suction force, and rotating magnetic field. We used thane MNS and feeding robot to simultaneously apply magnetic force and suction force to the UMR. In this process, we determined a current solution for generating magnetic force by using a linear optimization method. Finally, we conducted in vitro and in vivo experiments to verify the proposed method. In the in vitro experiment, which was in a glass tube environment, by using an RGB camera, we confirmed that the location of the delivery catheter in the glass tube could be recognized within an average error of 0.05 mm in each of the X- and Z-coordinates and that the retrieval success rate was greatly improved in comparison with that in the case without the use of magnetic force. In an in vivo experiment, we successfully retrieved the UMR in the femoral arteries of pigs. Full article
(This article belongs to the Special Issue Magnetic Microrobots for Biomedical Applications)
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11 pages, 6550 KiB  
Article
Robot-Aided Magnetic Navigation System for Wireless Capsule Manipulation
by Seyeong Im, Sungjun Kim, Joongho Yun and Jaekwang Nam
Micromachines 2023, 14(2), 269; https://doi.org/10.3390/mi14020269 - 20 Jan 2023
Viewed by 1576
Abstract
Magnetic navigation systems (MNSs) have been developed to use in the diagnosis of gastrointestinal problems. However, most conventional magnetic navigation systems are expensive and have structural problems because of their large weights and volumes. Therefore, this paper proposes C-Mag, a novel compact MNS [...] Read more.
Magnetic navigation systems (MNSs) have been developed to use in the diagnosis of gastrointestinal problems. However, most conventional magnetic navigation systems are expensive and have structural problems because of their large weights and volumes. Therefore, this paper proposes C-Mag, a novel compact MNS composed of two electromagnets and a robotic arm. The two electromagnets generate a planar magnetic field, and the robotic arm rotates and translates the electromagnets to manipulate the magnetic capsule in a large 3-dimensional (3-D) space. The C-Mag design considers the payload of the robotic arm and the capacity of the power supply unit. Under these limited conditions, the C-Mag was optimized to generate the maximum magnetic field considering several major factors. Finally, the C-Mag was constructed, and the maximum magnetic field that could be generated in one direction was 18.65 mT in the downward direction. Additionally, the maximum rotating magnetic field was 13.21 mT, which was used to manipulate the capsule. The performance was verified by measuring the generated magnetic field, and it matched well with the simulated result. Additionally, the path-following experiment of the magnetic capsule showed that the proposed C-Mag can effectively manipulate the magnetic capsule in 3-D space using the robotic arm. This study is expected to contribute to the further development of magnetic navigation systems to treat gastrointestinal problems. Full article
(This article belongs to the Special Issue Magnetic Microrobots for Biomedical Applications)
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11 pages, 8443 KiB  
Article
Wireless Inchworm-like Compact Soft Robot by Induction Heating of Magnetic Composite
by Woojun Jung, Seonghyeon Lee and Yongha Hwang
Micromachines 2023, 14(1), 162; https://doi.org/10.3390/mi14010162 - 8 Jan 2023
Viewed by 2124
Abstract
Microrobots and nanorobots have been produced with various nature-inspired soft materials and operating mechanisms. However, freely operating a wirelessly miniaturized soft robot remains a challenge. In this study, a wireless crawling compact soft robot using induction heating was developed. The magnetic composite heater [...] Read more.
Microrobots and nanorobots have been produced with various nature-inspired soft materials and operating mechanisms. However, freely operating a wirelessly miniaturized soft robot remains a challenge. In this study, a wireless crawling compact soft robot using induction heating was developed. The magnetic composite heater built into the robot was heated wirelessly via induction heating, causing a phase change in the working fluid surrounding the heater. The pressure generated from the evaporated fluid induces the bending of the robot, which is composed of elastomers. During one cycle of bending by heating and shrinking by cooling, the difference in the frictional force between the two legs of the robot causes it to move forward. This robot moved 7240 μm, representing 103% of its body length, over nine repetitions. Because the robot’s surface is made of biocompatible materials, it offers new possibilities for a soft exploratory microrobot that can be used inside a living body or in a narrow pipe. Full article
(This article belongs to the Special Issue Magnetic Microrobots for Biomedical Applications)
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13 pages, 1861 KiB  
Article
Improving Swimming Performance of Photolithography-Based Microswimmers Using Curvature Structures
by Liyuan Tan, Zihan Wang, Zhi Chen, Xiangcheng Shi and U Kei Cheang
Micromachines 2022, 13(11), 1965; https://doi.org/10.3390/mi13111965 - 12 Nov 2022
Cited by 2 | Viewed by 1856
Abstract
The emergence of robotic microswimmers and their huge potential in biomedical applications such as drug delivery, non-invasive surgery, and bio-sensing facilitates studies to improve their effectiveness. Recently, achiral microswimmers that have neither flexible nor helical structures have garnered attention because of their simple [...] Read more.
The emergence of robotic microswimmers and their huge potential in biomedical applications such as drug delivery, non-invasive surgery, and bio-sensing facilitates studies to improve their effectiveness. Recently, achiral microswimmers that have neither flexible nor helical structures have garnered attention because of their simple structures and fabrication process while preserving adequate swimming velocity and controllability. In this paper, the crescent shape was utilized to create photolithography-fabricated crescent-shaped achiral microswimmers. The microswimmers were actuated using rotating magnetic fields at low Reynolds numbers. Compared with the previously reported achiral microswimmers, the crescent-shaped microswimmers showed significant improvement in forward swimming speed. The effects of different curvatures, arm angles, and procession angles on the velocities of microswimmers were investigated. Moreover, the optimal swimming motion was defined by adjusting the field strength of the magnetic field. Finally, the effect of the thickness of the microswimmers on their swimming velocity was investigated. Full article
(This article belongs to the Special Issue Magnetic Microrobots for Biomedical Applications)
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10 pages, 1288 KiB  
Article
Quantitative Investigation of the Link between Actin Cytoskeleton Dynamics and Cellular Behavior
by Ying Li, Xiaoru Zhuang and Fuzhou Niu
Micromachines 2022, 13(11), 1885; https://doi.org/10.3390/mi13111885 - 1 Nov 2022
Cited by 1 | Viewed by 1556
Abstract
Actin cytoskeleton reorganization, which is governed by actin-associated proteins, has a close relationship with the change of cell biological behavior. However, a perceived understanding of how actin mechanical property links to cell biological property remains unclear. This paper reports a label-free biomarker to [...] Read more.
Actin cytoskeleton reorganization, which is governed by actin-associated proteins, has a close relationship with the change of cell biological behavior. However, a perceived understanding of how actin mechanical property links to cell biological property remains unclear. This paper reports a label-free biomarker to indicate this interrelationship by using the actin cytoskeleton model and optical tweezers (OT) manipulation technology. Both biophysical and biochemical methods were employed, respectively, as stimuli for two case studies. By comparing the mechanical and biological experiment results of the leukemia cells under electrical field exposure and human mesenchymal stem cells (hMSC) under adipogenesis differentiation, we concluded that β-actin can function as an indicator in characterizing the alteration of cellular biological behavior during the change of actin cytoskeleton mechanical property. This study demonstrated an effective way to probe a quantitative understanding of how actin cytoskeleton reorganization reflects the interrelation between cell mechanical property and cell biological behavior. Full article
(This article belongs to the Special Issue Magnetic Microrobots for Biomedical Applications)
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Review

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37 pages, 8420 KiB  
Review
A Review of Single-Cell Microrobots: Classification, Driving Methods and Applications
by Yuhang Wang, Jun Chen, Guangfei Su, Jiaxi Mei and Junyang Li
Micromachines 2023, 14(9), 1710; https://doi.org/10.3390/mi14091710 - 31 Aug 2023
Cited by 4 | Viewed by 2044
Abstract
Single-cell microrobots are new microartificial devices that use a combination of single cells and artificial devices, with the advantages of small size, easy degradation and ease of manufacture. With externally driven strategies such as light fields, sound fields and magnetic fields, microrobots are [...] Read more.
Single-cell microrobots are new microartificial devices that use a combination of single cells and artificial devices, with the advantages of small size, easy degradation and ease of manufacture. With externally driven strategies such as light fields, sound fields and magnetic fields, microrobots are able to carry out precise micromanipulations and movements in complex microenvironments. Therefore, single-cell microrobots have received more and more attention and have been greatly developed in recent years. In this paper, we review the main classifications, control methods and recent advances in the field of single-cell microrobot applications. First, different types of robots, such as cell-based microrobots, bacteria-based microrobots, algae-based microrobots, etc., and their design strategies and fabrication processes are discussed separately. Next, three types of external field-driven technologies, optical, acoustic and magnetic, are presented and operations realized in vivo and in vitro by applying these three technologies are described. Subsequently, the results achieved by these robots in the fields of precise delivery, minimally invasive therapy are analyzed. Finally, a short summary is given and current challenges and future work on microbial-based robotics are discussed. Full article
(This article belongs to the Special Issue Magnetic Microrobots for Biomedical Applications)
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Other

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12 pages, 2214 KiB  
Perspective
3D-Printed Microrobots: Translational Challenges
by Misagh Rezapour Sarabi, Ahmet Agah Karagoz, Ali K. Yetisen and Savas Tasoglu
Micromachines 2023, 14(6), 1099; https://doi.org/10.3390/mi14061099 - 23 May 2023
Cited by 2 | Viewed by 1457
Abstract
The science of microrobots is accelerating towards the creation of new functionalities for biomedical applications such as targeted delivery of agents, surgical procedures, tracking and imaging, and sensing. Using magnetic properties to control the motion of microrobots for these applications is emerging. Here, [...] Read more.
The science of microrobots is accelerating towards the creation of new functionalities for biomedical applications such as targeted delivery of agents, surgical procedures, tracking and imaging, and sensing. Using magnetic properties to control the motion of microrobots for these applications is emerging. Here, 3D printing methods are introduced for the fabrication of microrobots and their future perspectives are discussed to elucidate the path for enabling their clinical translation. Full article
(This article belongs to the Special Issue Magnetic Microrobots for Biomedical Applications)
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