Cortical potential imaging has been proposed as a method of imaging brain electrical activity with high spatial resolution. In cortical potential imaging, the potential on the brain surface is estimated using an electroencephalogram (EEG) of the scalp. In order to visualize the electrical activity of the brain, this study proposed the use of a spatial inverse filter with optimal filter property considering transfer matrix error. Moreover, the spatial inverse filter was expanded into a spatio-temporal filter to visualize changes in brain activity dynamically with time. The simulation results showed that the proposed method provided cortical potential mapping with higher accuracy than the conventional inverse imaging techniques. This method was applied to actual human EEGs of visually evoked potentials. We confirmed that the pathway toward generation of visual information could be visualized by estimated cortical potential mapping. Stabilization may be further improved by restricting filter parameters according to the spatio-temporal noise information from the EEG.

Commercially available above-knee prosthetic legs prescribed to above-knee amputees are composed of springs and dampers, which restrict the daily movements of transfemoral amputees, such as stair ascent. We propose a novel device that can be attached to multi- or single-axis prosthetic legs and maneuvered actively according to the user’s movements. The objective of this study was to develop an attachable cybernic unit and to confirm the basic capability of the system by evaluation with a stair ascent test. Using a four-linkage mechanism, the device can be operated without precise adjustment of the rotation axes of the prosthetic knee and the device. In addition, the dead point of the system can be avoided by designing a spring-operated dead point prevention mechanism and a thigh-fixing part with freedom of movement. In the stair ascent experiment, we confirmed that using the system, the subject ascended the steps as an able-bodied person. In conclusion, we developed an attachable cybernic unit that can be attached to multi- or single-axis prosthetic legs and maneuvered actively according to the user’s movements, and confirmed that the attachable cybernic unit facilitates difficult movements.

Frequently, by the time car drivers perceive the danger of a crash while driving, they may not be able to move to avoid it. This reaction is a protection reflex that occurs when danger is sensed. During this reaction period, it is difficult to take action in order to avoid danger by manually controlling a vehicle. If this emergency state could be detected by an electroencephalogram (EEG), it would be possible to avoid danger automatically. In this study, the possibility to detect emergency states during car driving from the phase-locking index (PLI) of EEG was investigated. Five healthy subjects drove in a virtual reality (VR) environment with obstacles suddenly appearing in front of the car. The subjects were requested to push down a switch to stop the car immediately when they found an obstacle, to avoid crashing. VR scenes were visually presented to subjects via head-mounted displays. Two kinds of distance conditions between the car and obstacle were tested:a“far”distance, with approximately 1 s between the appearance of and collision with the obstacle, in which it was relatively easy to avoid crashing by braking;and a “near” distance with approximately 0.3 s between obstacle appearance and collision, in which crashing was more difficult to avoid. A 50-channel EEG was measured, and both the PLI and averaged evoked potentials were calculated over the span of the trials. In four out of five subjects, the phase-locking EEG was observed during the negative evoked potential at 100ms after the obstacle appeared, and this occurred when the distance between the obstacle and the car was short, i. e. the near condition. As this phase-locking EEG response appeared immediately after the appearance of the obstacle, it is expected that the PLI of EEG can be used as an adequate indicator of an emergency state of the brain.

In this study, we proposed and developed a novel ultra-multijointed assistive mechanism for gripping, which can assist flexion and extension from the back of the hand. In addition, we confirmed the applicability of our mechanism to gripping of daily objects with assistance of flexion and extension by our mechanism. In the mechanism, many links are combined at the hinged joints, and a wire is inserted into the mechanism to transmit a bending force. To generate bending torque for the finger, the wire is pulled by the tip of the ultra-multijointed structure. When the wire is not pulled, no bending torque is generated for the finger, and the ultra-multijointed structure becomes flexible in the bending direction of the finger’s flexion and extension. By extruding this ultra-multijointed structure according to the finger surface length, which changes with flexion and extension, it is possible to adapt it to flex and extend for a wide range of finger postures for gripping daily objects. To confirm the applicability of the gripping assistant, we conducted experiments using a hand mockup and in a healthy volunteer. We have demonstrated the applicability of the assistive mechanism for providing assistive force to support fingers in gripping daily objects by assisting the flexion and extension of the fingers.

An increasing frequency of fall accidents associated with demographic aging in Japan has given rise to a need for effective fall prevention methods. Elderly people often use support devices such as canes and walking frames to reduce the risk of falling, but such measures may be inappropriate for certain environments. Previous research has shown that unsteadiness can be mitigated via light touch contact (LTC) with curtains or similar object at a force of up to around 1N, and the authors also previously proposed a virtual light touch contact (VLTC) approach based on LTC. VLTC supports standing stability based on a surrounding virtual partition connected to a vibrotactile fingertip stimulator. It is known that the posture retention effect is not achieved via simple continuous fingertip stimulation;rather, vibrotactile stimulation is required for control based on fingertip motion characteristics such as acceleration. However, with LTC the effect can be achieved via constant contact with a piece of paper or similar object without the need for fingertip movement. Assuming that reaction force from a fixed point fluctuates with body sway or psychological tremors in LTC, the LTC effect may be achievable by reproducing such fluctuations via vibrational stimulation. In this study, the authors proposed a novel VLTC method involving the use of vibration stimulation control to reproduce fluctuations in contact reaction force caused by the individual’s movement based on fingertip acceleration data. Verification of the method indicated a reduction of postural fluctuations similar to that achieved with LTC. This finding suggests that reduction of center-of-gravity sway achieved with LTC may be associated with slight changes in reaction force from a fixed point, which improves the position sense of the fingertip.

We developed a non-contact device that measures the volume of body fluids using microwave transmission. This device detects the phase difference between the radio waves that pass through the measurement target and the radio waves that do not pass through. When the radio waves pass through the water, the phase of the radio waves is delayed. The change in water volume cause phase differences, and our proposed device measures the relative temporal change of congestion without restraint. Deep vein thrombosis is caused by hypercoagulability, stagnation of blood flow, and vascular endothelial dysfunction. Remaining in a seated position for prolonged periods of time may cause deep vein thrombosis due to the stagnation of blood flow and may result in death. This device measures the volume of body fluids in the lower limbs. If venous congestion can be detected, we believe that the device will be developed as a new preventive measure for deep vein thrombosis. In this study, a subject’s lower leg was compressed with a cuff at a pressure of 60mmHg for 5 min to induce venous congestion. We simultaneously measured the changes in phase difference and the changes in the outer diameter of the calf by our proposed device and a strain gauge. The results showed a strong correlation between the change in the phase difference and the change in the outer diameter of the calf. These findings suggest that the proposed device is able to measure the volume of body fluids without contact. Future work may explore the application of the device for measuring fluids in the lower body of individuals who sit for prolonged periods of time, including in e-sports.

The present study aimed to validate a noncontact uroflowmeter developed by us. The noncontact uroflowmeter was compared to a medical uroflowmeter in terms of uroflowmetry variables. We used the uroflowmeters simultaneously to assess pseudourine and urine of healthy males, and compared the urinary flow pattern, voiding time, voided volume, and average and maximum urinary flow rates. Both uroflowmeters yielded similar urinary flow patterns. In the case of pseudourine, the two uroflowmeters differed significantly only in voiding time, which was significantly shorter with the noncontact uroflowmeter than with the medical uroflowmeter. However, with regard to urine, no significant differences were observed in the terms of uroflowmetry variables between the uroflowmeters. From these results, the possibility of using the noncontact uroflowmeter for medical use has increased.

Next-generation devices that allow continuous non-invasive blood pressure (cNIBP) monitoring are under development as alternatives to cuff-based sphygmomanometers. These include a volume-clamp method using transmural pressure control, a tonometer, and photoplethysmographic sensing based on either the pulse transit time or the second derivative signal. We have prepared a new standard for cuffless sphygmomanometer measurements. Here we report our efforts and discuss the current trends in regulation and approval of novel cNIBP monitoring devices.