BIBECHANA Vol. 20, No. 2, August 2023, 183–189 ISSN 2091-0762 (Print), 2382-5340 (Online) Journal homepage: http://nepjol.info/index.php/BIBECHANA Publisher:Dept. of Phys., Mahendra Morang A. M. Campus (Tribhuvan University)Biratnagar Structural analysis and material selection for biocompatible cantilever beam in soft robotic nanomanipulator Md. Shazib Uddin1, Md. Imran Khan2, Sadman Bin Shafiq3 Shahriar Sadik2, Md. Sohel Rana1,∗, Khaled Mohammad Shifullah Bhuiya1 Sabbir Ahmed Udoy1, Md. Khalid Hasan Rafi3 1Department of Mechanical Engineering, Rajshahi University of Engineering & Technology, Bangladesh 2College of Information Engineering, Yangzhou University, China 3School of Mechatronics, Mechanical Engineering, China University of Mining and Technology, China ∗Corresponding author. Email: sohel1702110@gmail.com Abstract This paper investigates the selection of appropriate materials for cantilever beams in sur- gical robotic nanomanipulators. Cantilever beams play a crucial role in soft robotic surgery. Biocompatible materials, which have minimal adverse effects on biological systems, are com- monly used for these beams. Using SOLIDWORKS software simulation, the study assesses the flexibility of cantilever beams made from different biocompatible materials. The analysis in- volves varying the applied force (0.001 µN to 0.004 µN), beam length (80 µm, 120 µm, and 160 µm), and beam thickness (0.4 µm, 0.6 µm, and 0.8 µm). Four materials—Alumina, Poly- Ether-Ether-Ketone (PEEK), Polyurethane (PUR), and Ti-6Al-4V—are evaluated. Simu- lation results highlight Polyurethane (PUR) as a suitable material for cantilever beams in nanomanipulators due to its favorable properties. These findings provide valuable insights for the design and advancement of efficient and reliable robotic nanomanipulators, advancing the field of soft robotic surgery. Keywords Cantilever beams, surgical robotic nano-manipulators, biocompatible materials, soft robotic surgery, simulation analysis. Article information Manuscript received: May 19, 2023; Accepted: June 20, 2023 DOI https://doi.org/10.3126/bibechana.v20i2.55037 This work is licensed under the Creative Commons CC BY-NC License. https://creativecommons. org/licenses/by-nc/4.0/ 183 http://nepjol.info/index.php/BIBECHANA sohel1702110@gmail.com https://doi.org/10.3126/bibechana.v20i2.55037 https://creativecommons.org/licenses/by-nc/4.0/ https://creativecommons.org/licenses/by-nc/4.0/ Md. S. Uddin et al./ BIBECHANA 20 (2023) 183-189 184 1 Introduction The term "mechatronics" refers to the coordinated use of physical systems, information technology (IT), and sophisticated decision-making through- out the design, production, and use of industrial goods and processes [1]. In the mechatronic field, the robot is a crucial term. The Robotic Institute of America defines a robot as "a reprogrammable, multifunctional manipulator designed to move ma- terials, parts, tools, or specialized devices through various programmed motions for the performance of a variety of tasks," which is the definition that is currently most frequently used [2]. Today, robotic nano-manipulators are used in surgery applications. Nanomanipulator is a device created to control items at the nanoscale or a microscope attached to a virtual reality (VR) interface that enables the user to virtually teleport to the sample surface. Due to the numerous biological and material sci- ence applications of nanomanipulator, it has re- cently attracted a lot of interest. Nanomanipu- lator is demonstrated by the definition of mate- rial qualities, creation of electronic chipsets, test- ing of microelectronic circuits, teleoperation of op- erations, micro-injection, and manipulation of chro- mosomes and genes [3]. Nanomanipulator involves a variety of scenarios, but the most common ones are those that use scanning tunneling microscopy (STM), atomic force microscopy (AFM), and nano- robotic manipulator (NRM) [4]. The cantilever beam is one of the important parts of a robotic nanomanipulator in the field of soft robotic surgery applications. Minimally invasive surgery (MIS), particularly for abdominal procedures, has estab- lished itself as the industry standard [5]. A can- tilever beam can be utilized as a part of the tool or instrument to manipulate tissues or carry out treatments at the microscopic level. Typically com- patible materials are used in soft robotic cantilever beams because of their flexibility. Biocompatible materials are those that can interact with biolog- ical systems without harming them or producing unfavorable effects. These materials are employed in a variety of medical and healthcare applications. In Neurosurgery, minimally invasive techniques are employed for the biopsy operation (Fig. 1) which required precisely placing a device into a brain le- sion. To access the tumor, the physician drills a hole in the skull and inserts a biopsy probe where a cantilever beam is used [6]. In Gynaecologic surgery, each Zeus system con- tains two physically separate subsystems known as "Surgeon-side" and "Patient-side" shown in (Fig. 2). The surgeon-side console consists of two han- dles for operating the robotic arms and a display for documenting the surgical operation. The sur- geon console controls three robotic arms that are mounted above the operating table as a compo- nent of the patient-side subsystem. The biocompat- ible material is used as a cantilever beam in these robotic arms [7]. In minimally invasive surgery, by replacing and increasing human skills, minimally in- vasive surgery (MIS) can increase patient safety and the effectiveness of medical interventions [8]. The development of surgical instrumentation that can access the surgical target through numerous small entrances (Fig. 3) which employed the cantilever beam. The aforementioned applications show that the cantilever beam is widely used in medical ap- plications. These cantilever beams are composed of biocompatible materials. There is a limited num- ber of studies that focused on single biocompatible material as a cantilever beam independently. But the response of the cantilever beam depends on the type of material, the width, length, and applied force. Hence, optimization of the material and the effect of the influential parameters is important and such studies seem not to exist in the available liter- ature. The objective of this study is to optimize the biocompatible materials and to investigate the ef- fect of influential parameters on the response of the biocompatible materials in cantilever beam under specific conditions using the SOLIDWORKS simu- lation software. 2 Methodology This section describes the selection of the material, assumption and boundary condition, and simula- tion setup for the cantilever beam. 2.1 Selection of the Materials The author has selected four types of biocompat- ible materials like Alumina, PUR (Polyurethane), PEEK (Poly-Ether-Ether-Ketone), and Ti-6Al-4V (titanium alloys). The basis of selection is dis- cussed as follows. Alumina-based bio-ceramic ma- terials are considered one of the best materials to use in biomedical engineering because of their ex- cellent biomechanical and biocompatibility proper- ties [9]. The three main subcategories of bioceram- ics are bioinert, bioactive, and bioresorbable ceram- ics [10]. Alumina and zirconia, two bio-inert ce- ramics with high mechanical and chemical stability, exhibit a "contact osteogenesis" pattern when in touch with bone tissue [11–14]. PUR is a versatile elastomer that exhibits exceptional flexibility and resilience. It has superior impact resistance, low friction, and vibration damping qualities. These qualities make it ideally suited for soft robotic appli- cations. PEEK is a high-performance thermoplas- tic that is renowned for its superior mechanical at- tributes, such as high strength, stiffness, and chemi- cal resistance. It is used in soft biomedical engineer- Md. S. Uddin et al./ BIBECHANA 20 (2023) 183-189 185 ing applications due to its advantageous mechani- cal properties [15] for soft robotic applications. Ti- 6Al-4V is the alloying system titanium-aluminum vanadium type VT-6 (6Al-4V, Grade5, SAT-64, T- A6V, Ti-Al-V) with an average aluminum content of 6% and vanadium - 4% are the most widely used titanium alloys in additive industries [16] and soft robotic applications. The mechanical properties of the materials are listed in Table 1. 2.2 Boundary Condition and Assumption The fixed end of the cantilever beam is fastened to hard support, which prevents motion in all direc- tions. The force is applied to the cantilever beam’s free end. The cantilever beam is unrestricted in its ability to bend and move in transitional directions means movements can include bending and deflec- tion, other than axially. The forces were varied from 0.001 µN to 0.004 µN. Then the thickness and length were set up at three different values for each material: 80 µm, 120 µm, and 160 µm for length, and 0.4 µm, 0.6 µm, and 0.8 µm for thickness. How- ever, the value of the width is kept fixed. It has been assumed that the materials will re- act linearly and elastically. The cantilever beam is said to be made of homogeneous materials, each of whose characteristics is thought to remain constant throughout. The cantilever beams will only expe- rience modest deflections, keeping the beam within its elastic range. 2.3 Simulation Setup At first, the static Structural analysis has been cho- sen. Then 3D geometry of the cantilever beam has been developed using the sketching module employ- ing the dimensions. After that, the material selec- tion and settings of the material attributes have been fixed from the software database using the drop-down menu. The assumption and boundary condition has been set using the simulation module. The load, length, and thickness of the cantilever beam have been selected as the variable parame- ters during the simulation. The mesh is generated for the computational domain to discretize the ge- ometry of the cantilever beam. Optimization of the mesh generation has been done using the trial and error method. The finite element analysis (FEA) was utilized to simulate the structural response of the beam under various loading scenarios. Table 1: Properties of different bio-compatible materials. Properties Alumina PUR PEEK Ti-6Al-4V Elastic Modulus(N/m2) 3.7×1011 2.41×109 3.9×109 1.02×1011 Poisson’s Ratio 0.22 0.3897 0.4 0.31 Mass Density(kg/m3) 3960 1260 1310 4428.784 Tensile Strength(N/m2) 3×108 4×107 9.5×107 1.01×109 Thermal Expansion Coefficient( / K ) 7.4×10−6 4×10−5 3.6×10−3 9×10−6 Thermal Conductivity(W/m. k) 30 0.2681 0.24 6.9 Specific Heat(J/ kg. k) 850 1900 1850 586.04 Sources: SolidWorks software 3 Results and Discussion This section describes the simulation results of the four types of materials obtained at different influ- ential parameters. 3.1 Optimization of the Materials Figure 4 shows the effect of applied force on the de- flection of the materials. Overall, from this graph, we can easily figure out the deflection of cantilever beams made of different materials. The applied force ranged from 0.001µN to 0.004 µN. It is evi- dent from the graph that deflection increases with increasing force. Polyurethane (PUR) exhibits the maximum deflection, while Alumina represents the minimum deflection. PEEK and Ti-6Al-4V show a moderate level of deflection. Thus, Polyurethane (PUR) demonstrates the greatest degree of flexibil- ity compared to the other three materials (Alumina, PEEK, and Ti-6Al-4V). As displacement is a mea- sure of material flexibility, it can be concluded that Polyurethane is the best material among the four. Md. S. Uddin et al./ BIBECHANA 20 (2023) 183-189 186 Figure 1: Application of surgical robot with Can- tilever beam biopsy [2]. Figure 2: (A) Zeus surgical telemanipulator system. (B) Robotic instrument arms and Aesop endoscope arm (not sterile-draped) at the operating table [ [17]]. Figure 3: Envisaged surgical scenario with a ma- nipulator [18]. Figure 4: (Effect of applied force on the deflection of the material [L=80 µm, Width=10 µm, thick=0.6 µm]. 3.2 Effect of Applied Force on PUR De- flection Figures 5, 6, and 7 show the displacement of a can- tilever beam made of Polyurethane material with three types of loads. The values of length, width, and thickness are kept fixed, while only the forces vary. It is observed that the beam deflection in- creases with increasing load. 3.3 Effect of Beam Length on PUR Deflec- tion Simulation results in Figures 8, 9, and 10 indicate that displacement/deflection increases with increas- ing beam length at the micrometer scale. The val- ues of force, width, and thickness are kept fixed. 3.4 Effect of Beam Thickness on PUR De- flection Figures 11, 12, and 13 depict the simulation of the cantilever beam with variable thickness. These fig- ures show that the displacement of the beam de- creases with increasing thickness. The values of force, length, and width are kept fixed. 3.5 Simulation Results in Terms of Mag- nitude Figure 14 illustrates how the deflection of the beam changes with the applied force corresponding to the length. It is observed from the graph that as the force increases, the cantilever beam shows maxi- mum deflection for the maximum length at 160µm, whereas for the minimum length at a length of 80µm, the cantilever beam shows the minimum de- flection. Moreover, Figure 15 is a line graph that illustrates how the beam deflection decreases with increasing width. In this figure, it can be observed that for the maximum thickness of 0.8µm, the min- imum deflection of the beam is observed, while for the minimum thickness of 0.4µm, the maxi- mum deflection is found. These two graphs indicate that polyurethane beams with maximum possible lengths and minimum thickness exhibit greater de- flection, indicating a higher level of flexibility that is expected for the surgical soft robotic application of a nanomanipulator. Md. S. Uddin et al./ BIBECHANA 20 (2023) 183-189 187 Figure 5: Graphical result of the cantilever beam made of Polyurethane (PUR); L= 80 µm, width= 10 µm, thickness = 0.6 µm [F=0.001µN]. Figure 6: Graphical result of the cantilever beam made of Polyurethane (PUR); L= 80 µm, width= 10 µm, thickness = 0.6 µm [F=0.003µN]. Figure 7: Graphical result of the cantilever beam made of Polyurethane (PUR); L= 80 µm, width= 10 µm, thickness = 0.6 µm [F=0.004µN]. Figure 8: Graphical result of the cantilever beam made of PUR at F=0.001µN, width=10 µm, thick- ness=0.6 µm [L=80 µm]. Figure 9: Graphical result of the cantilever beam made of PUR at F=0.001µN, width=10 µm, thickness=0.6 µm [L=120 µm]. Figure 10: Graphical result of the cantilever beam made of PUR at F=0.001µN, width=10 µm, thick- ness=0.6 µm [L=160 µm]. Md. S. Uddin et al./ BIBECHANA 20 (2023) 183-189 188 Figure 11: Graphical result of the cantilever beam made of PUR at F=0.001µN, L=80 µm, Width=10 µm [Thickness=0.4µm]. Figure 12: Graphical result of the cantilever beam made of PUR at F=0.001µN, L=80 µm, Width=10µm [Thickness=0.6µm]. Figure 13: Graphical result of the cantilever beam made of PUR at F=0.001µN, L=80 µm, Width=10 µm [Thickness=0.8µm]. Figure 14: PUR deflection as a function of applied force corresponding to the length. Figure 15: PUR deflection as a function of applied force corresponding to the thickness. 4 Conclusion Polyurethane cantilever beams show great poten- tial as a nanomanipulator in the fields of robotics and biology because it shows highest flexibility. Polyurethane is a flexible material with respect to biocompatibility and resilience to wear and tear. The polyurethane manipulator can provide the nec- essary dexterity and flexibility while working with biological systems at the molecular and cellular level. It could function more subtly inside the human body. A surgeon may work more pre- cisely with less tissue injury using a nanomanip- ulator utilizing its high level of precision control. Polyurethane lessens the likelihood of an adverse response when used with human body parts. As Md. S. Uddin et al./ BIBECHANA 20 (2023) 183-189 189 a biocompatible material complies with scientific standards, polyurethane can be utilized in surgical procedures involving delicate human body parts. References [1] M. Tomizuka. Mechatronics: From the 20th to 21st century. Control Engineering Practice, 10(9):877–886, 2002. [2] S. Najarian and et al. Advances in medical robotic systems with specific applications in surgery – a review. Journal of Medical En- gineering and Technology, 35(1):19–33, 2011. [3] R. Saeidpourazar and et al. 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Introduction Methodology Selection of the Materials Boundary Condition and Assumption Simulation setup Results and Discussion Optimization of the Materials Effect of Applied Force on PUR Deflection Effect of Beam Length on PUR Deflection Effect of Beam Thickness on PUR Deflection Simulation Results in Terms of Magnitude Conclusion