Driving modes and characteristics of biomedical micro-robots

Micro-robots(MRs)are miniature machines with dimensions smaller than 1 mm and have semior fully-autonomous capabilities,including sensing,decision-making,and performing operations.These MRs have garnered significant attention in the precision medicine and personalized treatment field due to their ability to navigate narrow areas of the human body with non-desirable fluid flow.Specifically,MRs are actuated by a mechanism that generates propulsive force through the interaction between MRs’actuation modules and external energy sources in a specific direction.This driving mechanism enables the precise execution of medical treatment such as targeted drug delivery and minimally invasive surgeries.Nonetheless,MRs currently encounter certain challenges in clinical practice,including reliance on external energy sources,short lifespan,and difficulties in degradation or recovery within the human body.This article aims to review the common components and characteristics of driving mechanism for MRs’actuation modules,propose possible solutions to address current clinical challenges,and ultimately,explore the desirable structural and functional composition for the future development of MRs.Through these efforts,this review hopes to provide guidance for the future development of MRs in the field of precision medicine.

Noninvasive method to drive medical micro-robots

A noninvasive method to drive medical micro-robots into endocoeles has been proposed and a kind of medical micro robot driven by the method has been designed. The robot has a spirally grooved impeller. When the spirally grooved impeller rotates, a hydrodynamic film between the robot and endocoeles is formed because of mucus existence in endocoeles. The generated axial thrust force of the impeller can drive robots to move. Because the hydrodynamic film is formed when the robot moves in endocoeles, injury may be prevented, so it can alleviate or avoid pain of sufferers. The generated axial thrust force of the impeller has been estimated according to the hydrodynamic lubrication theory and has been confirmed by experiments.

Development of a non-cable whole tectorial membrane micro-robot for an endoscope

A novel non-cable whole tectorial membrane micro-robot for an endoscope is developed. The micro-robot we have fabricated and tested can propel itself in the intestine tract of a pig in an autonomous manner by earthworm-like locomotion. The silicone of bellow shape is laid over the outer surface of the micro-robot to reduce the affection of the viscoelastic properties of the intestine. Wireless power transfer and communication systems are employed to realize the non-cable locomotion of the mi-cro-robot. The prototype of the micro-robot is 13.5 mm in diameter and 108 mm in length. The experimental results show that the towing force for the micro-robot is about 0.8 N, which is much smaller than the maximum driving force 2.55 N of the linear actuator. The supplying power of the wireless power transfer system fulfills the needs of the micro-robot system and the mi-cro-robot can creep reliably in the large intestine of a pig and other contact environments.

Study of an inchworm-like micro-robot

A micro-robot with 4 DOFs is presented in this paper. An inchworm-like biped mechanical structure is selected with the advantages of small size and minimal weight. It can walk on wall as an inchworm with two different locomotion modes such as crawling and overturn. With rotation mode, this robot can change it＇ s motion direction. The robot can also transit between different surfaces. The kinematics model of the robot has been analyzed. A DSP based embedded controller is used for minimal power consumption and efficient control. The micro-robot can move flexibly and fit complicated un-structural environment well.

MICRO-ROBOT FOR MEASUREMENT AND THREE-DIMENSION RECONSTRUCTION OF MICROPIPES

The presented system consists of field devices, a control system and a host computer system. The field devices, which are composed of an in-pipe micro-robot, a displacement sensor, a curvature sensor, and an inner surface measurement unit, can go into the pipe to get the data of displace- ment and axis curvature, and the shape data of the inner surface. With the conic-shape laser beam shot by the inner surface measurement unit, the intersectional curve between the laser beam and the inner-surface of the tested pipe can be calculated in the local coordination system （LCS） of the inner surface measurement unit. The relation between the LCS and the global coordination system （GCS） can be deduced, too. After the robot reaches the end of the pipe, all measured intersectional curves can be translated into the same coordination system to become a point cloud of the inner surface of the pipe according to the relations between LCS and GCS. Depending on this points cloud, the CAD model of the inner surface of the pipe can be reconstructed easily with reverse engineering tools, and the feature of flaw of the pipe can be obtained with flaw analysis tools.

A Novel Dual Helical Magnetorheological Fluid Micro-Robot

To address the problem of flexible drive control of gastrointestinal(GI)tract micro-capsule robot posture,a novel dual helix magnetorheological fluid(MRF)micro-robot(DHMRFMR)is proposed and developed in this paper.Based on the mechanical properties of magnetorheological fluid,the relationship model of magnetic field force is obtained,and the thrust model is established.Double micro DC deceleration motor is used to drive the two ends of the helical actuator to make the DHMRFMR forward and backward,by changing the external magnetic field rotation speed,direction and distance,adjust the attitude direction of the robot.Numerical simulation software ANSYS is used to analyze the motion law of external fluid of DHMRFMR,and the visualization of fluid velocity and pressure distribution is realized.The front-end helix actuator can change the flow path of the fluid,and the middle and tail of the DHMRFMR bear less pressure,which improves the stability and flexibility of the robot.The novel DHMRFMR is suitable for internal drive in bending environment,and has a good application prospect in biomedical engineering field in human intestinal unstructured environment.

Analysis of Electromagnetic Exposure in Wireless Power Transfer System for Endoscopic Micro-robot

A wireless power transfer system for endoscopic micro-robot operating at 36 kHz is presented in this paper. The issue of patient＇ s health and safety regarding exposure to the electromagnetic field is addressed. The specific absorption rate and current density can be used to investigate the electromagnetic influences on the biological tissues surrounded by the wireless power launching coil. In view of this purpose, the limited close-ound solenoid electromagnetic model is built, the relationship between the electric intensity and the specific absorption rate and current density is deduced, and the simulation experiments are done. Experimental results show that the values of SAR and current density related to different tissue catalogs are all very small and do not exceed their own limits respectively when the resonance frequency of operation is 36 kHz.

基于学习生物体运动的一种人工筋驱动器的研究

本文从仿生学的观点，学习生物体的原理，研究微型机器人的机构和控制问题，是开发微型机电系统的一个关键技术。介绍了生物体运动的基本特征，并从学习生物体运动的设计原理出发，对一种具有与人体肌肉类似特性的空气压人工筋进行了实验研究，表明它有可能成为一种新颖的柔性进机器人的驱动器，在医疗及微小空间作业的特种机器人中获得应用。

Modeling and Configuration Design of Electromagnetic Actuation Coil for a Magnetically Controlled Microrobot

Non-contact actuated microbeads have attracted a lot of attention in recent years because of its enormous potential in medical, biological, and industrial applications. Researchers have proposed a multitude of electromagnetic actuation(EMA) systems consisting of a variety of coil pairs. However, a unified method to design and optimize a coil pair according to technical specifications still does not exist. Initially, this paper presented the modeling of an untethered ferromagnetic particle actuated by externally applied magnetic field. Based on the models, a simple method of designing and optimizing the EMA coil pair according to technical specifications, was proposed. A loop-shaped coil pair generating uniform magnetic and gradient fields was chosen to demonstrate this method clearly and practically. The results of the optimization showed that the best distance to radius ratio of a loop-shaped coil pair is 1.02 for a uniform magnetic field and 1.75 for a uniform gradient field. The applicability of the method to other shapes of coil configuration was also illustrated. The best width to distance ratio for a square-shaped coil pair is 0.558 and 0.958 for uniform magnetic and gradient fields, respectively. The best height to width ratio and distance to width ratio for a rectangle-shaped coil pair is h/w =[0.9,1.1], d/w =[0.5,0.6] for uniform magnetic field and h/w =[1.0,1.2], d/w =[0.9,1.1] for uniform gradient field. Furthermore, simulations of a microparticle tracking the targeted trajectory were conducted to analyze the performance of the newly designed coils. The simulations suggested the ability of manipulating microparticles via the coils designed by our proposed method. The research mainly proposed a unified design and optimization method for a coil pair, which can support researchers while designing a specific coil pair according to the technical requirements. This study is aimed at researchers who are interested in EMA system and microrobots.