We demonstrate mapping of three-dimensional (3D) structure to determine details of surface profiles of the ear canal and auricle. In order to measure the surface profile of the ear canal, we developed an optical scanner for inner surface profile measurement, and clarified the optical properties of the cone beam. When the standard deviation of 7-mm ring gauges made of high-density polyethylene was measured, the error of measurement was ±0.05mm. Then, we compared the three-dimensional mapping of the ear canal between our method and a contact three-dimensional surface profile measurement method. The difference between the two methods was －0.15mm, and the full width at half maximum was ±0.58mm. Moreover, we achieved three-dimensional mapping for not only the ear canal, but also the auricle using an articulated arm based on kinematics. Our research provides three-dimensional mapping to determine surface profiles from the eardrum to auricle, without using impression materials.
The study aimed to investigate factors related to the characteristics of the lower arch of the foot using the arch height ratio calculated from the dorsum height and foot length. A nonlinear regression analysis, SVM-RFE, was conducted using low arch as the dependent variable and patient attributes as explanatory variables to identify factors related to lower arch of the foot. This survey recruited 1,178 community-dwelling participants (485 men, 693 women) in Japan. A questionnaire was administered, and the foot arch ratio was measured. There were 207 participants in the low arch group and 971 in the non-low arch group. Age, height, weight, foot length, and body mass index were used as explanatory variables. From the classification of explanatory variables by SVM RFE, age, foot length, and weight were identified as factors related to the foot arch. Although there were few explanatory variables in the present study, SVM RFE was an effective method for analysis of factors associated with lower arch of the foot.
In recent years, the application of electrogastrogram (EGG) to functional gastric disorder evaluation has attracted attention. However, in the case of EGG measurement, gastric electrical activity signals included in the EGG are easily contaminated by artifacts and noise from other organs with the same frequency band. Therefore, it is necessary to apply signal processing techniques that can extract only gastric electroactive components. On the other hand, since gastric electrical activity is non-linear and non-stationary, it is impossible to have an absolute answer when we evaluate the performance of signal processing. In order to solve this problem, we propose a model generating EGG mathematically, which can be applied to evaluate signal processing. First of all, we prepared a mathematical model with a white Gaussian noise source and a mathematical model of gastric electrical activity as proposed in previous research. In the next step, various numerical solutions were generated by changing two control parameters. These numerical solutions were compared with measured EGGs. EGGs used for model evaluation were measured from 4 subjects. Evaluations were performed using amplitude distribution and frequency distribution. The results showed that some numerical solutions closely resembled the measured EGGs. These optimal numerical solutions may be used for the evaluation of analytical methods.
Gait festination (GF) is one of the representative locomotion disturbances associated with Parkinsonism, which induces pulsion caused by increased stepping velocity. Fear of falling over and involuntary symptoms caused by GF can have a significant impact on quality of life. Considering previous interventional strategies for GF and their utility in daily life, physical intervention using a wearable system to assist postural disorder and the hastening phenomenon is necessary for patients with GF. The purpose of this study was to develop a wearable system that can assist the patient in extending the trunk and generating internal rhythm. Another objective was to confirm the effectiveness of the system for preventing GF by conducting a gait experiment in a Parkinsonism patient. To design an assistive method, we simulated lateral swing in the standing position based on features of Parkinsonism, and defined the mechanism and power configurations for the system. A power unit at the back of the waist transmits a cyclic force to the chest by a link in the frontal plane. A gait experiment was performed in a Parkinsonism patient with GF to confirm that reduction of the gait cycle is prevented by using the system. The result showed that the linear trendline slope of reduction of the gait cycle decreased. In addition, the maximum stooping angle decreased by half, and the cyclic assistance of the system and gait cycle were harmonized. These results suggest that the system developed is effective in preventing GF by supporting posture and generating internal rhythm.
Early detection of muscle strain injury caused by excessive stress is important to prevent progression of injury. However, slight injuries are difficult to detect with current measurement technologies. Our study relates the electrical impedance to the injury-induced change in the tissue composition, and proposes a portable and reproducible detection system of injured muscle. The proposed system scans the exciting and sensing positions using multiple electrodes placed on the body surface, and obtains multi-dimensional potential data related to the impedance distribution. Any injury is then discriminated in the data. To ensure a robust discrimination without measurements of injured muscle, the discrimination parameters were optimized using the data computed by a potential simulation model representing the muscle strain injury together with the possible noise and measurement data obtained from normal samples. In the experiment, we applied an AC voltage of 10kHz in a circuit and scanned the surface potential with 16 electrodes. The injury-discrimination performance was then assessed using a phantom representing the electrical characteristics of the leg muscle. In phantoms representing normal tissues and three-stage injured samples, wefirst investigated the noise level of the electrode position that maximized the discrimination rate. The maximum discrimination rate of the proposed system was 88.3%for a Gaussian noise with a 0.24mm standard deviation. Applying the noise settings that maximized the discrimination rate, we then evaluated the discrimination rate of injured tissue at locations not included in the learning data. The system delivered similar discrimination performance at different injured locations compared with the small injured sample. Therefore, the proposed method is expected to detect slight muscle strain injuries using a simple hardware setup.
Manikin-type epidural insertion simulators for epidural anesthesia training have been evaluated by asking anesthesiologists’feeling compared with their personal experiences. In order to evaluate the epidural insertion simulators from the engineering point of view, the author inserted an endoscope into the epidural space for visualization of the ligamentum flavum model (LF) and the needle tip, and measured the reaction force as needle insertion resistance and the pressure inside the syringe for the loss of resistance technique (LOR) . According to the LOR, after the epidural needle was inserted into the epidural insertion simulator, the inner needle was withdrawn and a pressure sensor and a syringe were attached to the needle. Both the needle and a load cell were moved in the epidural insertion simulator at a speed of 0.8mm/s. From the endoscopic images, the author obtained the timing for both needle puncture of the LF and catheter insertion as entrance of the whole needle tip into the epidural space. Two needles were compared;a needle with tip angle of 25 degrees was designated needle A, and one of 38 degrees was designated needle B. Experimental results of seven insertions for both needles A and B were as follows. (1)Tenting of the LF was the largest when the needle tip punctured the LF. (2)The pressure inside the LOR syringe started to decrease at the location of 1.41±0.65mm in needle A and 1.74±1.01mm in needle B prior to the largest tenting of the LF. (3)Insertion length and force required from puncturing of the LF to insertion of the whole needle tip into the epidural space were 3.19±0.46m and 2.36±0.35N, respectively, for needle A, and 2.64±0.29m and 2.34±0.34N for needle B. The difference in insertion length was statistically significant (p＜0.01) due to the longer bevel of needle A. (4)Insertion of the dull needle B into the epidural space required 9.38±0.83N, which was greater than that of needle A (8.49±0.87N) (p＜0.05) . Epidural insertion simulator with an endoscope for visualization of the epidural space is useful for understanding the relation between tenting of the LF and pressure inside the LOR syringe. The LF of the current epidural insertion simulator should be improved for practicing catheter insertion.
We propose a method of non-contact oxygen saturation measurement, which is simpler and less expensive than conventional camera methods. We constructed a simple system using a camera lens and a phototransistor. We considered that measurement with this system is possible using pulse oximetry to calculate percutaneous oxygen saturation. In order to confirm whether change in oxygen saturation can be measured using the proposed system, we conducted a breath holding experiment and performed measurements simultaneously using the proposed system and a transmission pulse oximeter. The experiment was conducted in a lighted room with the subject sitting in a chair. The subject breathed for 2 minutes and then held the breath for as long as possible. Measurement was continued for 3 minutes after the subject resumed breathing. For the proposed system, the measurement target was the left-hand middle finger nail, and the distance from the camera lens to the pedestal on which the measurement target was placed was set at 100mm. The pulse oximeter was attached to the little finger of the left hand. From the results of the experiment, the proposed system showed a general response in which the oxygen saturation level decreased when a subject held the breath and gradually returned to normal level when breathing was resumed. These findings suggest that the proposed method is able to estimate oxygen saturation in a non-contact manner.