Journal of Biomechanical Science and Engineering
Online ISSN : 1880-9863
ISSN-L : 1880-9863
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Displaying 1-6 of 6 articles from this issue
Papers
  • Yuki KITAZAWA, Yoshiki SUGAWARA, Masakazu TAKEDA, Ryota IKEDA
    2025 Volume 20 Issue 1 Pages 24-00052
    Published: 2025
    Released on J-STAGE: January 15, 2025
    Advance online publication: June 16, 2024
    JOURNAL OPEN ACCESS

    This study proposes a motion analysis method for human-machine systems involving contact phenomena. When human skin comes into surface contact with objects, the flexibility of the skin and the friction between the epidermis and the object can result in different state distributions on the skin surface, such as stick/slip and contact/floating. We introduce a discretized model for motion analysis to express the state distributions and internal deformations. In the proposed method, contact phenomena, including friction, are formulated as a mathematical problem called the linear complementarity problem (LCP), and the flexibility of the skin is modeled using a mass-spring-damper model. We propose a hybrid integration method (Moreau’s midpoint method for epidermis motion analysis and the Runge-Kutta method for subcutaneous tissue motion analysis) to simultaneously address non-smooth phenomena such as friction and large deformations. In this method, the motion of the epidermis and subcutaneous tissue affect each other via virtual springs and dampers. As a preliminary investigation, real motion measurements are conducted for a fingertip sliding on a plane surface to verify the phenomena occurring on the skin. Subsequently, the analysis using the proposed method revealed trends similar to those observed in the motion measurements, demonstrating the effectiveness of the proposed method for analyzing the motion of skin in contact with objects.

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  • Akihiro KUROSAWA, Masahiro HIGUCHI, Hiroshi TACHIYA, Kaoru TADA, Atsur ...
    2025 Volume 20 Issue 1 Pages 24-00098
    Published: 2025
    Released on J-STAGE: January 15, 2025
    Advance online publication: June 16, 2024
    JOURNAL OPEN ACCESS

    Osteoarthritis (OA) of the thumb carpometacarpal (CMC) joint is a common disease in hand OA. Low joint congruity could increase articular stress in the CMC joint and is thus considered among the risk factors for CMC OA. However, this relationship has not been clarified. This study aimed to examine whether low joint congruity correlated with high stress on the articular surface of the CMC joint. CT images were obtained for 14 healthy subjects in eight static limb positions during flexion and extension, and 3D CMC joint models were created. First, cross-sectional images of the CMC joint in the dorsal–volar and radial–ulnar directions were acquired, and the curvature radius ratio between the trapezium and the first metacarpal was then calculated as the joint congruity from these images using image processing and curve fitting. Subsequently, a finite element (FE) model was created, and the maximum value of compressive stress was evaluated. Finally, the correlation coefficients between joint congruity and compressive stress were assessed. As a result, a negative correlation was found between the joint congruity in the volar–dorsal direction and the compressive stress in the trapezium (R = -0.648, p<0.001), showing that low congruity increases the compressive stress on the articular surface of the trapezium. This finding suggests that a low joint congruity contributes to the onset of CMC OA. This could help predict the risk of OA and improve treatments and prevention measures for CMC OA.

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  • Hiroki ISHIZUKA, Shoki KITAGUCHI, Masashi NAKATANI, Hidenori YOSHIMURA ...
    2025 Volume 20 Issue 1 Pages 24-00027
    Published: 2025
    Released on J-STAGE: January 15, 2025
    Advance online publication: June 19, 2024
    JOURNAL OPEN ACCESS

    This study presents a computational model that simulates the responses of tactile afferents, which are essential for designing tactile devices in addition to understanding the mechanism of tactile perception of vibrotactile stimuli. We employed finite element method analysis to simulate skin deformation accurately, and the leaky integrate-and-fire model to simulate the neural dynamics of tactile afferents. Previous studies using these models have failed to model the responses of tactile afferents to vibrotactile stimuli; therefore, we developed a computational model that can better reproduce the neural responses to vibrotactile stimuli, considering the appropriate filters. We subsequently validated this model by calculating the firing rates of tactile afferents in response to several vibrotactile stimuli. Our proposed computational model outperformed conventional models when evaluated using the averaged root mean square error. Overall, our results demonstrate the potential of our method to model the activities of tactile afferents and will provide insights into the development of not only computational neural models but also tactile devices.

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  • Kazuto TAKASHIMA, Hiroto HIDAKA, Akinori NAMBA, Yoichi HAGA, Makoto OH ...
    2025 Volume 20 Issue 1 Pages 24-00230
    Published: 2025
    Released on J-STAGE: January 15, 2025
    Advance online publication: September 27, 2024
    JOURNAL OPEN ACCESS

    Many guidewire penetration accidents occur during catheter introduction. Therefore, we have evaluated the behavior of medical devices such as guidewires and catheters during catheter introduction using numerical simulations. In our previous study, we evaluated the effects of the insertion velocity of the guidewire and the catheter and confirmed that during catheter introduction, the guidewire imparted a greater load on the vessel wall than that exerted by the guidewire alone. However, it was unclear whether the above phenomenon could also occur under other conditions. In the present study, in addition to these effects, we evaluate the effects of the blood vessel elastic modulus, device insertion length, blood vessel centerline curvature, and their interactions. Furthermore, we evaluate the behavior of the medical devices during guidewire removal after catheter introduction, which was not evaluated in our previous study. We determine the simulation conditions based on the design of experiments and investigate the dominant parameters that affect the contact force between the medical devices and the blood vessel wall using two methods (one that considers parameter interactions and one that does not). We confirm that during guidewire insertion and removal, the device velocity and the vessel centerline curvature have the largest effects, respectively. For the guidewire and the catheter during catheter introduction, the vessel elastic modulus and the insertion velocity have the largest effects, respectively, and the parameter interactions have large effects. These findings are clinically important because they are counterintuitive. During catheter introduction, the average contact forces are larger than those during both guidewire insertion and removal. Furthermore, during guidewire removal, the catheter tip moves in the distal direction.

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  • Yuji SHIMOGONYA, Juanfang RUAN, Takayuki KATO, Takuji ISHIKAWA,, Keiic ...
    2025 Volume 20 Issue 1 Pages 24-00284
    Published: 2025
    Released on J-STAGE: January 15, 2025
    Advance online publication: October 18, 2024
    JOURNAL OPEN ACCESS
    Supplementary material

    The magnetotactic bacterium MO-1 possesses a pair of unique flagellar apparatuses. Each apparatus comprises seven flagella and 24 thin fibrils enclosed in a sheath. Using these apparatuses, the cells swim at high speed through solutions, tracing helical trajectories. The mechanism by which MO-1 cells utilize their two flagellar apparatuses to propel the cell body remains unclear. Due to the short length of the flagellar apparatus, direct observation of individual movements under a microscope is technically challenging. In this study, we performed numerical simulations based on the boundary element method to investigate the swimming motility of MO-1 cells. Our cell models successfully reproduced the helical trajectories of active MO-1 cells. The two flagellar apparatuses were positioned at the front and back of the cell body relative to the direction of movement. The cell body was pulled by the anterior flagellar apparatus and pushed by the posterior apparatus. The swimming motion of the cell model exhibited minimal changes near a wall. This unique swimming behavior of MO-1 cells could only be achieved through the rotation of both flagellar apparatuses. Based on the revolution rate of active MO-1 cells, we estimated the rotational speed of the flagellar apparatus to be approximately 1200 s-1. This rapid rotation may result from the tight packing of flagellar filaments within the sheath. Our study elucidates the mechanism by which active MO-1 cells swim in helical trajectories.

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