Bio-Medical Materials and Engineering - Volume 24, issue 6

Authors: Yu, Chang Ho | Kang, Seung Rok | Kwon, Tae Kyu

Article Type: Research Article

Abstract: This research was performed to assess the effects of angled whole body vibration on muscle activity of the lower limbs, by examining adults in their twenties during squat exercises, taking into account two variables of exercise intensity (vibration frequency and gradient). Twenty healthy males in their twenties with previous experience of more than 6 month's weight training and no past medical history were included in this study. The experiment was performed by participating in squat exercises which consisted of 3 sets (1 set = 5 seconds x 3 repetitions of exercise), and the muscle activities of the Rectus Femoris, Vastus …Lateralis, Vastus Medialis were measured with variation in the gradients of 0°, 10°, and 20°, and vibration frequencies of 20, 30, and 40 Hz. At 30 and 40 Hz, the vastus lateralis showed the highest change in muscle activity, while activity of the vastus medialis also increased significantly. Analysis of muscle activity according to the gradient showed a significant increase of the vastus lateralis at 20°, while the highest muscle activity at 20° was observed for the vastus medialis. In comparison of the change in lower limb muscle activity according to simultaneous stimulation, at a gradient of 10°, high activity was shown in muscle, while at 20°, high muscle activities were produced at 40 Hz in the vastus lateralis, 40 Hz in the rectus femoris, and both 30 and 40 Hz in the vastus medialis Show more

Keywords: Lower limb, muscle activity, exercise instrument for whole body vibration

DOI: 10.3233/BME-141057

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 6, pp. 2437-2445, 2014

Authors: Son, Jongsang | Ryu, Jeseong | Kim, Jungyoon | Kim, Youngho

Article Type: Research Article

Abstract: In this study, a simple method based on the dynamic equation of motion was introduced to determine the moment of inertia using a commercial dynamometer, and an optimization technique was utilized to estimate inertial parameters with the determined moment of inertia. To evaluate the feasibility of the developed method, three different passive speeds (i.e. 240, 270 and 300°/s) were chosen to confirm whether the moment of inertia values are the same irrespective of angular speeds. Moreover, the estimated inertial parameters (i.e., the mass, center of mass and moment of inertia) of the elbow attachment and the disk-like 3 kg-weight were …compared with solutions of uniform square cube and solid disk, respectively. As a result, the values of moments of inertia of the elbow attachment were 0.216 ± 0.017, 0.215 ± 0.016 and 0.216 ± 0.017 kg·m2 at angular speeds of 240, 270 and 300°/s, respectively. The values of the moment of inertia of both the attachment and weight were 0.821 ± 0.054, 0.823 ± 0.058 and 0.824 ± 0.053 kg·m2 at angular speeds of 240, 270 and 300°/s, respectively. There were no significant differences among the speeds. The estimated inertial parameters of the attachment or the weight were very similar to the theoretical values. Therefore, it is expected that the developed method has the potential to estimate inertial parameters of a human body segment and to improve the accuracy and reliability of the studies on human dynamics. Show more

Keywords: Inertial parameters, mass, center of mass, radius of gyration, moment of inertia

DOI: 10.3233/BME-141058

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 6, pp. 2447-2455, 2014

Authors: He, Wenbo | Wang, Yuan | Gong, Xiaoyan

Article Type: Research Article

Abstract: Generating an artificial blood flow in a circle system is an important step in hemodynamic research; thus, the influence of circle system components on the pulsatile flow wave forms should be investigated. In this study, a circle system was built, in which two solenoid valves were controlled by a timer to transform a constant flow into a pulsatile one, and two customized compliances with five different aeration volumes were set up upstream and downstream of the test chamber, achieving twenty-five different wave forms. Then, the influence of the compliance settings on the flow rate wave form was investigated. From the …experimental data, it can be concluded that the absolute value of the maximum value and the minimum value of the wave forms increases along the aeration of the downstream compliance but decreases along the aeration of the upstream compliance. For the second maximum value and the offset between the maximum value and the minimum value, remarkable differences were obtained between runs with aeration of zero compliance and nonzero compliance. Finally, an emulational flow was achieved with the up- and downstream aeration volume equaling 360mL and 180mL, respectively, which fit the realistic wave form well. Show more

Keywords: Pulsatile flow, compliance, particle image velocimetry, circle system, abdominal aortic aneurysms

DOI: 10.3233/BME-141059

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 6, pp. 2457-2463, 2014

Authors: Zhu, Zhiwen | Zhang, Wendi | Xu, Jia

Article Type: Research Article

Abstract: A kind of shape memory alloy (SMA) hysteretic nonlinear model is developed, and the stochastic bifurcation characteristics of SMA intravascular stents subjected to radial and axial excitations are studied in this paper. A new nonlinear differential item is introduced to interpret the hysteretic phenomena of SMA strain-stress curves, and the dynamic model of SMA intravascular stent subjected to radial and axial stochastic excitations is established. The conditions of the system's stochastic stability are determined, and the probability density function of the system response is obtained. Finally, the stochastic Hopf bifurcation characteristics of the system are analyzed. Theoretical analysis and numerical …simulation show that the system stability varies with bifurcation parameters, and stochastic Hopf bifurcation occurs in the process; there are two limit cycles in the stationary probability density of the system response in some cases, which means that there are two vibration amplitudes whose probability are both very high; jumping phenomena between the two vibration amplitudes appears with the change of conditions, which may cause stent fracture or loss. The results of this paper are helpful for application of SMA intravascular stent in biomedical engineering fields. Show more

Keywords: Shape Memory Alloy (SMA), intravascular stent, stochastic load, global stability, stochastic bifurcation

DOI: 10.3233/BME-141060

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 6, pp. 2465-2473, 2014

Authors: Yu, Chang Ho | Kang, Seung Rok | Jeong, Ho Choon | Kim, Kyung | Kwon, Tae Kyu

Article Type: Research Article

Abstract: This study was performed to assess the improvement of muscle strength imbalance in the lower limbs using a four point weight bearing reduction system with a two-belt treadmill. Participants, each having differences in muscle function of the left and right legs of over 20%, were divided into two groups of ten. The participants were involved in experiments progressing 40 minutes per day, 3 days per week, during a period of 4 weeks. The maximal peak torque and average power were measured for testing joint torque in the hip, knee and ankle. The results showed the improvement of muscle imbalance as …assessed by the maximal muscle strength was the most effective in the hip joint, while the improvement of muscular reaction was the most effective in the knee joint. We suggest that the method of weight bearing reduction could be sufficient to reduce muscle imbalance in the lower limbs. Show more

Keywords: Reduction of weight bearing, joint torque, gait, muscle imbalance, two-belt treadmill

DOI: 10.3233/BME-141061

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 6, pp. 2475-2483, 2014

Authors: Seo, Jeong-Woo | Kang, Dong-Won | Kim, Ju-Young | Yang, Seung-Tae | Kim, Dae-Hyeok | Choi, Jin-Seung | Tack, Gye-Rae

Article Type: Research Article

Abstract: In this study, the accuracy of the inputs required for finite element analysis, which is mainly used for the biomechanical analysis of bones, was improved. To ensure a muscle force and joint contact force similar to the actual values, a musculoskeletal model that was based on the actual gait experiment was used. Gait data were obtained from a healthy male adult aged 29 who had no history of musculoskeletal disease and walked normally (171cm height and 72kg weight), and were used as inputs for the musculoskeletal model simulation to determine the muscle force and joint contact force. Among the phases …of gait, which is the most common activity in daily life, the stance phase is the most affected by the load. The results data were extracted from five events in the stance phase: heel contact (ST1), loading response (ST2), early mid-stance (ST2), late mid-stance (ST4), and terminal stance (ST5). The results were used as the inputs for the finite element model that was formed using 1.5mm intervals computed tomography (CT) images and the maximum Von-Mises stress and the maximum Von-Mises strain of the right femur were examined. The maximum stress and strain were lowest at the ST4. The maximum values for the femur occurred in the medial part and then in the lateral part after the mid-stance. In this study, the results of the musculoskeletal model simulation using the inverse-dynamic analysis were utilized to improve the accuracy of the inputs, which affected the finite element analysis results, and the possibility of the bone-specific analysis according to the lapse of time was examined. Show more

Keywords: Musculoskeletal modeling, finite element analysis, inverse dynamics

DOI: 10.3233/BME-141062

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 6, pp. 2485-2493, 2014

Authors: Chen, Duanduan | Zhong, Yi | Shinohara, Kyosuke | Nishida, Tomoki | Hasegawa, Toshiaki | Hamada, Hiroshi

Article Type: Research Article

Abstract: The cilia, presenting a rotational movement in the embryonic nodes, play a crucial role in the left-right specification during embryogenesis. The characteristic architecture of these cilia is based on a cylindrical arrangement of 9 doublet microtubules and the motion of the cilia is triggered by the dynein motors located between adjacent doublets by converting the chemical energy into mechanical work. Restricted by the inherent difficulties of experiments, the dynein activation patterns in moving cilia cannot be directly observed. Thus, the mechanism of nodal ciliary movement is still unclear. In this study, we present computational models of the nodal ciliary ultrastructure …based on tomographic images of the ciliary body. By employing time accurate three-dimensional solid mechanics analysis, we investigate the dynein-triggered sliding between adjacent doublet microtubules and simulate the induced ciliary bending. As an exploratory study, two dynein activation patterns are proposed and their rationality is discussed. The mathematical model presented by this paper provides a platform to investigate various assumptions of dynein activity, facilitating us to propose the most possible dynein activation pattern and therefore improving our understandings regarding the protein-beating problems of cilia. Show more

Keywords: Cilia, dynein, ultrastructure, embryonic node, finite element analysis

DOI: 10.3233/BME-141063

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 6, pp. 2495-2501, 2014

Authors: Shin, Dong Ho | Lim, Hyung-Gyu | Jung, Eui Sung | Wei, Qun | Seong, Ki Woong | Lee, Jyung Hyun | Lee, Seung-ha | Cho, Jin Ho

Article Type: Research Article

Abstract: Since the 1980's, various types of implantable hearing aids using unique means for delivering acoustic power to the inner ear have been developed. Recently, implantable hearing aids that stimulate the round window by the middle ear transducer have received great attention because it reduces loading effect at the ossicular chain. In this study, we have implemented a direct install 3-pole type EM transducer in round window niche for implantable middle ear hearing aid. The 3-pole type EM transducer consists of two permanent magnets and three coils and exhibit structural features that minimize leakage flux, thereby permitting high efficiency and low …magnetic field interference. The stapes velocity was measured using a laser Doppler vibrometer in response to the round window stimulation from the transducer. To verify the usefulness of the 3-pole type EM transducer, we compared the stapes vibration characteristics produced by the transducer and those from a sound source. The magnitude of stapes velocity due to the round window stimulation at 1 mArms was equivalent to that of stapes velocity at 94 dB SPL sound stimulation. Thus, the evaluation study shows that the 3-pole type EM transducer is suitable for implantable hearing devices. Show more

Keywords: 3-pole type EM transducer, round window, stapes velocity, implantable hearing aids

DOI: 10.3233/BME-141064

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 6, pp. 2503-2510, 2014

Authors: Wang, Tong | Xing, Zhongwen

Article Type: Research Article

Abstract: This paper presents a fluid-particle interaction algorithm using the distributed Lagrange multiplier based fictitious domain method. The application of this method to the numerical investigation of motion and aggregation of red blood cells in two-dimensional microvessels is discussed. The cells are modelled as rigid biconcave-shaped neutrally buoyant particles. The aggregating force between two cells is derived from a Morse type potential function. The cell-cell interaction is coupled with the fluid-cell interaction through a time splitting scheme. Simulation results of multiple red blood cells in Poiseuille flow are presented. Because of its modular nature, this algorithm is applicable to a large …class of problems involving the processes of particle aggregation and fluid-particle interaction. Show more

Keywords: Fluid-particle interaction, red blood cells, aggregation, mathematical modelling

DOI: 10.3233/BME-141065

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 6, pp. 2511-2517, 2014

Authors: Veshkina, Natalia | Zbicinski, Ireneusz | Stefańczyk, Ludomir

Article Type: Research Article

Abstract: In this study, a fluid-structure interaction analysis based on the application of patient-specific mechanical parameters of the aneurismal walls was carried out to predict the rupture side during an abdominal aortic aneurysm (AAA). Realistic geometry of the aneurysm was reconstructed from CT data acquired from the patient, and patient-specific flow conditions were applied as boundary conditions. A newly developed non-invasive methodology for determining the mechanical parameters of the patient-specific aortic wall was employed to simulate realistic aortic wall behaviors. Analysis of the results included time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and von Mises stress (VMS). Results of …the TAWSS, OSI, and VMS were compared to identify the most probable region of the AAA's rupture. High OSI, which identified the region of wall degradation, coincided with the location of maximum VMS, meaning that the anterior part of the aneurismal wall was a potential region of rupture. Show more

Keywords: Fluid-structure interaction, abdominal aortic aneurysm, mechanical parameters of the aortic wall, computed tomography, computational fluid dynamics

DOI: 10.3233/BME-141066

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 6, pp. 2519-2526, 2014