In ultrasonography, the reproducibility of imaging is poor because ultrasound images change depending on factors such as the contact force or contact angle with the imaging target. This study developed a measurement module for the contact force on an imaging target for an ultrasound probe. The contact force measurement module consists of a set of probe-side parts, a set of hand-side parts, four 6-axis force sensors, and an inertial sensor. The two sets of the probe-side and hand-side parts are connected only by the 6-axis force sensors so that the reaction force of the contact force from the measurement object can be applied only to the sensors. In addition, the gravity effect of the probe mass depending on the probe angle can be compensated for by measuring the attitude of the module using the inertial sensor. In this study, a prototype contact force measurement module was fabricated. The contact force measurement characteristics of the prototype were evaluated by varying the angle of the probe. In the experiment, the contact force was measured by operating an ultrasound probe with the module to contact the target surface vertically as well as by a load cell placed under the target surface. The values measured by the module were compared to those measured by the load cell at the －30, 0, 15, and 30° angles. The values measured by the module increased linearly with an increase in the values measured by the load cell under all conditions. The slope of the approximate line between the value measured by the load cell and that measured by the module was 0.98 and the R² value was 0.9999 at an angle of 0°. The slopes and R² values of －30, 15, and 30°were comparable with those of 0°. This result suggests that the proposed module can be applied to the contact force measurement in ultrasonography without depending on the angle of the ultrasound probe to the horizontal plane.

In this study, we developed a tourniquet based on the EHD pump. A tourniquet is a medical device that pneumatically stops bleeding in limbs during orthopedic surgery, thereby securing the surgical site. Generally, the hemostatic pressure from a tourniquet is determined based on a rule of thumb, and there is no clear standard for this. As a result, the limbs are compressed at a constant high pressure, resulting in residual damage. In a previous study using rat models, we confirmed that the higher the pressure, the greater the damage to the body and the lower the tissue oxygen saturation (rSO₂) in the vicinity of the compression point. Additionally, we highlighted the possibility of reducing damage to living tissue by fine-tuning the stopping pressure based on rSO₂. However, fine adjustment of the pressure with a conventional pneumatic tourniquet is difficult to achieve because of the complexity of the system. Therefore, we considered using the EHD pump, which can adjust the pressure only by voltage. We developed a tourniquet equipped with an rSO₂ measurement unit that can fine-tune the pressure using the EHD pump as a driving source. We evaluated the time response and accuracy of pressure adjustment and conducted experiments to adjust the hemostatic pressure using rSO₂ as an index. The results confirmed that the proposed EHD tourniquet has superior controllability that enables more detailed pressure setting and adjustment. In addition, by incorporating a function that automatically adjusts the compression pressure according to changes in rSO₂ using in data from an on-board rSO₂ measurement device, we confirmed that the compression pressure is automatically adjusted according to the rSO₂ through actual clinical tests on humans.

Understanding the complex excitation dynamics within the atrium is crucial in catheter ablation treatment for persistent non-paroxysmal atrial fibrillation. Previously, the ExTRa Mapping^TM system was developed to measure the inside of an atrium using a 20-pole catheter and present images of excitation propagation in real time. However, this system generates excitation propagation images independently for each measurement position only in two dimensions. This study thus proposes a method that maps excitation propagation images generated by the ExTRa Mapping^TM system onto a three-dimensional (3D) atrial model, enabling 3D visualization of excitation propagation data at multiple positions. In particular, the heatmap mode, which visualizes the distribution of the rotors (phase singularities) as a heatmap, can serve as an effective indicator for catheter ablation. To illustrate the effectiveness of the proposed method, we visualized five actual cases. We also conducted a user study to confirm the feasibility and practicality of our proposed method, for which physicians and technicians generally provided positive feedback.

For health management purposes, a system has been developed to acquire electrocardiograms (ECGs) while bathing in a bathtub equipped with electrodes. The bathers were people who lived in the same house and personal identification is required to classify ECG data of each bather. As with the acquisition of bathtub ECGs, personal identification should be performed unconsciously and unconstrained. Bathing involves thermal and hydrostatic stresses. Bathtub ECG changes with increased heart rate and cardiac output due to bathing. In this study, a machine learning long short-term memory model was used to train an ECG of 100 beats immediately before and after bathing to identify individuals. The results showed a 100% identification rate. To evaluate the robustness of the training model to noise, white noise of 50% and 100% intensity relative to the amplitude of the R- to S-waves was added to the ECG of the training data. Subsequently, the average identification rates reduced to 94.6% and 45.1%, respectively. This suggests that the noise up to about 50% of the intensity relative to the amplitude of the R- to S-wave could maintain a high identification rate.

Stroke often causes asymmetry in gait parameters, such as step length and double support time, which negatively affects walking ability and quality of life. While slower walking speeds are associated with greater asymmetry, spatiotemporal symmetry in stroke survivors cannot be fully explained by walking speed alone. Neurological factors, including the lesion site and corticospinal function, must also be considered. This study aimed to elucidate the relationship between walking speed, spatiotemporal symmetry, and corticospinal drive in stroke survivors. A total of 22 chronic stroke survivors and 10 healthy older adults participated in the study. Gait analysis was performed using a double-belt treadmill and synchronized three-dimensional motion capture. Electromyography signals were collected from the bilateral tibialis anterior (TA), soleus, and gastrocnemius muscles. Coherence in the β-band was quantified as the area under the curve (AUC) to assess corticospinal connectivity. In healthy participants, AUC significantly increased during fast walking compared to normal walking (p＝0.001-0.02). Stroke survivors were divided into subgroups based on four symmetry indices, including step length and double support time. Only the subgroup with consistent double support time symmetry showed a significant increase in AUC of TA from normal to fast walking (p＝0.04). No significant differences in AUC were found in the other subgroups or in step length symmetry (p＝0.58). The findings suggest that maintaining double support time symmetry, regardless of walking speed, may reflect more efficient corticospinal control. Stroke survivors who achieved this symmetry exhibited gait dynamics similar to those of healthy individuals, with coordinated muscle activation across both lower limbs. These results underscore the importance of assessing spatiotemporal symmetry during gait interventions and highlight the need to consider neurological control alongside functional outcomes.

Cardiogenic shock (CS) is a circulatory failure with a poor prognosis. The intra-aortic balloon pump (IABP), one of the mechanical circulatory support devices, is the most widely used for treating CS. However, clinical trials have not demonstrated its efficacy in treating CS with IABP. In this study, we systematically examined the effects of IABP on perfusion of the central and peripheral organs, including the brain and kidneys, in addition to the systemic and coronary circulation, and explored the optimization and maximization of IABP’s effects. Using a normal canine model (N＝1), we measured blood pressure, ventricular pressure, left and right atrial pressures, cardiac output, and blood flow in the coronary, carotid, and renal arteries, comparing the presence and absence of IABP. To fit the diameter of the dog’s aorta, we custom-made two balloons with diameters of 6mm and 8mm. Diastolic augmentation and systolic unloading by the IABP were observed in the aortic pressure waveform, and both balloons increased coronary flow and decreased left ventricular systolic pressure. Still, the 8mm balloon had a greater effect than the 6mm balloon. The impact on aortic pressure and cardiac output was minimal. However, distal aortic pressure decreased, and renal blood flow was reduced with both balloons. This study revealed that balloon diameter significantly affects the efficacy of IABP and suggested that this model and experimental system are useful for optimizing IABP.

The use of electroencephalogram (EEG) in medicine has been established as an objective evaluation method of brain function as “electroencephalography.” Even today, when diagnostic imaging such as CT and MRI are widely used, the size, cost and temporal resolution of the equipment limits its use in the research of brain function, making research using EEG an essential method. In recent years, Brain Machin Interface (BMI) has attracted attention as an application of EEG in the biomedical engineering field, and its clinical use is also advancing in the rehabilitation field. EEG is also used in affective research and neurofeedback applications, and has potential for future development. This section describes the principles, methods, terminology, and techniques of EEG measurement for researchers who are interested in starting research using EEG.

To improve the quality of journal papers in the Advanced Biomedical Engineering as well as the Transactions of Japanese Society for Medical and Biological Engineering, the Editors-in-Chief held roundtable discussions on various issues including initial checks on submitted manuscripts (ethical issues, COI, and recommendations by the International Committee of Medical Journal Editors), improving the template files and the submission system, originality criteria, journal impact factor, article publishing charge (APC) and J-STAGE Data, etc. The editors also discussed future plans for educational seminars and articles. By publicizing editorial policies including the above issues to society members, the editorial committee aims to further improve the quality of journal papers and to enhance the journals’ presence.