Wearable Fabric Loop Sensor Based on Magnetic-Field-Induced Conductivity for Simultaneous Detection of Cardiac Activity and Respiration Signals.

In this study, a noncontact fabric loop sensor based on magnetic-field-induced conductivity, which can simultaneously detect cardiac activity and respiration signals, was developed and the effects of the sensor's shape and measurement position on the sensing performance were analyzed. Fifteen male subjects in their twenties wore sleeveless shirts equipped with various types of fabric loop sensors (spiky, extrusion, and spiral), and the cardiac activity and respiratory signals were measured twice at positions P2, P4, and P6. The measurements were verified by comparing them against the reference electrocardiogram (ECG) and respiratory signals measured using BIOPAC® (MP150, ECG100B, RSP100C). The waveforms of the raw signal measured by the fabric loop sensor were filtered with a bandpass filter (1-20 Hz) and qualitatively compared with the ECG signal obtained from the Ag/AgCI electrode. Notwithstanding a slight difference in performance, the three fabric sensors could simultaneously detect cardiac activity and respiration signals at all measurement positions. In addition, it was verified through statistical analysis that the highest-quality signal was obtained at the measurement position of P4 or P6 using the spiral loop sensor.

Efficacy of tooth brushing via a three-dimensional motion tracking system for dental plaque control in school children: a randomized controlled clinical trial.

BACKGROUND: School children are in a developmental period in which permanent teeth replace primary dentition. It is also a period with a high incidence of gingivitis and caries, which can be improved with adequate tooth brushing. Advances in information technology have led to the development of smart health devices that assist in tooth brushing. We compared the effectiveness of computer-assisted toothbrushing using a toothbrushing instruction (TBI) method called the smart toothbrush and smart mirror (STM) system with that of conventional TBI (verbal instructions) for plaque control in school children. METHODS: This randomized controlled clinical trial analyzed and compared the reduction of the modified Quigley-Hein plaque index between the two methods in 42 school children. The participants were randomly assigned to the STM system group (n = 21) or conventional-TBI group (n = 21). The plaque indices were evaluated at baseline, immediately after TBI (day 0), and 1 week and 1 month after TBI. RESULTS: The STM system and conventional TBI led to an average reduction of 40.50% and 40.57%, respectively, in whole mouth plaque. Reductions in the plaque indices within each tested time period were observed in both groups (P < 0.001), and the mean plaque reduction did not differ between the two groups (P = 0.44). CONCLUSIONS: The present study tested a computer assisted system for TBI, more studies are needed to confirm its usefulness in different objectives. Clinical relevance The computer-assisted STM system may be an alternative of TBI for children. Trial registration ClinicalTrials.gov (NCT04627324) Registered 13/11/2020-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04627324 .

Conditions for CNT - Coated Textile Sensors Applied to Wearable Platforms to Monitor Limb Joint Motion.

Despite recent research on joint motion measurement to monitor human body movement, current measurement techniques and tools have significant limitations, including requiring large space for measurement and causing discomfort in test subjects wearing motion sensors. Our study aims, first, to develop carbon nanotube (CNT)-based textile joint motion sensors. Second, ours study aims to identify the most suitable CNT-based sensor structure and attachment method for use on a wearable platform during general exercise speeds. Lastly, we used these sensors on the human body, using sleeves and legs to find the most stable location, and we used the CNT-based sensor condition to monitor joint motions. We utilized our CNT-based sensor, which has proper elasticity as well as conductivity, and applied it to the elbow and knee joints. Based on the strain gauge principle, we monitored the variance of electric resistance that occurred when the CNT-based sensor was stretched due to limb motion. Our study tested 48 types of sensors. These sensors were applied to the CNT using different base knit textiles as well as different attachment methods, layers, sensor lengths, and sensor widths. The four most successful sensor types, which showed superior efficacy over the others in joint motion measurement, were selected for further study. These four sensors were then used to measure the elbow and knee joint motions of human subjects by placing them on different locations on sleeves and legs. The CNT knit textile sensors best suited to measuring joint motions are those with a double-layered CNT knit and 5 cm long × 0.5 cm or 1 cm wide sensors attached to a polyester¬-based knit using a welding method. The best position for the sensor to more stably monitor joint motions was the "below hinge position" from the elbow or knee hinge joint. Our study suggests an alternative strategy for joint-motion measurement that could contribute to the development of more comfortable and human-friendly methods of human limb motion measurement.

The Effect of Electrode Designs Based on the Anatomical Heart Location for the Non-Contact Heart Activity Measurement.

This research is an extension of a previous research [1] on the different effects of sensor location that is relatively suitable for heart rate sensing. This research aimed to elucidate the causes of wide variations in heart rate measurements from the same sensor position among subjects, as observed in previous research [1], and to enhance designs of the inductive textile electrode to overcome these variations. To achieve this, this study comprised two parts: In part 1, X-ray examinations were performed to determine the cause of the wide variations noted in the findings from previous research [1], and we found that at the same sensor position, the heart activity signal differed with slight differences in the positions of the heart of each subject owing to individual differences in the anatomical heart location. In part 2, three types of dual-loop-type textile electrodes were devised to overcome variations in heart location that were confirmed in part 1 of the study. The variations with three types of sensor designs were compared with that with a single-round type of electrode design, by using computer simulation and by performing a t-test on the data obtained from the experiments. We found that the oval-oval shaped, dual-loop-type textile electrode was more suitable than the single round type for determining morphological characteristics as well as for measuring appropriate heart activity signals. Based on these results, the oval-oval, dual-loop-type was a better inductive textile electrode that more effectively overcomes individual differences in heart location during heart activity sensing based on the magnetic-induced conductivity principle.

Removal of baseline wandering in ECG signal by improved detrending method.

The very first step to process electrocardiogram (ECG) signal is to eliminate baseline wandering interference that is usually caused by electrode-skin impedance mismatch, motion artifacts due to a patient's body moment or respiratory breathing. A new method is thus suggested to remove baseline wandering in ECG by improving the detrending method that was originally proposed for eliminating slow non-stationary trends from heart rate variability (HRV). In our proposed method, a global trend is estimated in terms of baseline wandering by merging the local trend based on an ECG segment that represents a part of the ECG signal. The experimental results show that the improved detrending method can efficiently resolve baseline wandering without distorting any morphological characteristic embedded in the ECG signal in no time delay manner.

Efficacy of computer-assisted, 3D motion-capture toothbrushing instruction.

OBJECTIVE: The objective of this study was to compare the efficacy of computer-assisted TBI using a smart toothbrush (ST) and smart mirror (SM) in plaque control to that of conventional TBI. MATERIALS AND METHODS: We evaluated the plaque removal efficacy of a ST comprising a computer-assisted, wirelessly linked, three-dimensional (3D) motion-capture, data-logging, and SM system in TBI. We also evaluated the efficacy of TBI with a ST and SM system by analyzing the reductions of the modified Quigley-Hein plaque index in 60 volunteers. These volunteers were separated randomly into two groups: conventional TBI (control group) and computer-assisted TBI (experimental group). The changes in the plaque indexes were recorded immediately, 1 week, 1 month, and 10 months after TBI. RESULTS: The patterns of decreases in the modified Quigley-Hein plaque indexes were similar in the two groups. Reductions of the plaque indexes of both groups in each time period were observed (P < 0.0001), and the effects of TBI did not differ between the two groups (P = 0.3803). All volunteers were sufficiently motivated in using this new system. CONCLUSION: The reported new, computer-assisted TBI system might be an alternative option in controlling dental plaque and maintaining oral hygiene. CLINICAL RELEVANCE: Individuals can be motivated by the new system; meanwhile, comparable effects of controlling dental plaque can be achieved.

A practical method for the detection of freezing of gait in patients with Parkinson's disease.

PURPOSE: Freezing of gait (FOG), increasing the fall risk and limiting the quality of life, is common at the advanced stage of Parkinson's disease, typically in old ages. A simple and unobtrusive FOG detection system with a small calculation load would make a fast presentation of on-demand cueing possible. The purpose of this study was to find a practical FOG detection system. PATIENTS AND METHODS: A sole-mounted sensor system was developed for an unobtrusive measurement of acceleration during gait. Twenty patients with Parkinson's disease participated in this study. A simple and fast time-domain method for the FOG detection was suggested and compared with the conventional frequency-domain method. The parameters used in the FOG detection were optimized for each patient. RESULTS: The calculation load was 1,154 times less in the time-domain method than the conventional method, and the FOG detection performance was comparable between the two domains (P=0.79) and depended on the window length (P<0.01) and dimension of sensor information (P=0.03). CONCLUSION: A minimally constraining sole-mounted sensor system was developed, and the suggested time-domain method showed comparable FOG detection performance to that of the conventional frequency-domain method. Three-dimensional sensor information and 3-4-second window length were desirable. The suggested system is expected to have more practical clinical applications.

The effect of textile-based inductive coil sensor positions for heart rate monitoring.

In the research related to heart rate measurement, few studies have been done using magnetic-induced conductivity sensing methods to measure the heart rate. The aim of this study was to analyze the effect of the position of a textile-based inductive coil sensor on the measurement of the heart rate. In order to assess the capability of the textile-based inductive coil sensor and the repeatability of measured cardiac muscle contractions, we proposed a new quality index based on the morphology of measured signals using a textile-based inductive coil sensor. We initially explored eight potential positions of the inductive sensor in a pilot experiment, followed by three sensor positions in the main experiment. A simultaneously measured electrocardiography (ECG) signal (Lead II) which was used as a reference signal for a comparison of the R-peak location with signals obtained from selected positions of the textile-based inductive coil sensor. The result of the main experiment indicated that the total quality index obtained from the sensor position 'P3', which was located 3 cm away from the left side from the center front line on the chest circumference line, was the highest (QI value = 1.30) among the three positions across all the subjects. This finding led us to conclude that (1) the position of the textile-based inductive coil sensor significantly affected the quality of the measurement results, and that (2) P3 would be the most appropriate position for the textile-based inductive coil sensor for heart rate measurements based on the magnetic-induced conductivity sensing principle.

Measurement of high-resolution mechanical contraction of cardiac muscle by induced eddy current.

There are many types of devices which help to manage a personal health conditions such as heartbeat chest belt, pedometer and smart watch. And the most common device has the relationship with heart rate or ECG data. However, users have to attach some electrode or fasten the belt on the bare skin to measure bio-signal information. Therefore, most of people want more convenient and short-ready-time and no-need to attach electrode. In this paper, we proposed the high-resolution measuring system of mechanical activity of cardiac muscle and thereby measure heartbeat. The principle of the proposed measuring method is that the alternating current generate alternating magnetic field around coil. This primary magnetic field induces eddy current which makes magnetic field against primary coil in the nearby objects. To measure high-resolution changes of the induced secondary magnetic fields, we used digital Phase-locked loop(PLL) circuit which provides more high-resolution traces of frequency changes than the previous studies based on digital frequency counter method. As a result of our preliminary experiment, peak-peak intervals of the proposed method showed high correlation with R-R intervals of clinical ECG signals(r=0.9249). Also, from signal traces of the proposed method, we might make a conjecture that the contraction of atrium or ventricle is reflected by changing conductivity of cardiac muscle which is beating ceaselessly.

Analysis of lower limb bradykinesia in Parkinson's disease patients.

AIM: Bradykinesia of the lower limb is an important limiting factor of the quality of life in parkinsonian patients. This study aims to develop quantitative measures of bradykinesia and to investigate the possible dissociation of amplitude and velocity measures and their dependence on movement direction during toe-tapping. METHODS: Subjects included 39 patients with PD, as well as 14 healthy control subjects. A gyrosensor on the dorsum of a foot was used to measure ankle joint movement during toe-tapping. Four representations (root-mean square, mean peak, coefficient of variation in peaks, peak in the last 5 s) for each of amplitude and velocity and for each of plantar flexion and dorsiflexion movement of toe-tapping were investigated. Outcome measures were compared between patients and controls, and their correlations with clinical scores were investigated. Category distributions of outcome measures in patients were analyzed. RESULTS: All outcome measures were smaller in patients than in controls (P < 0.001) and correlated well with clinical scores (P < 0.01). The mean peak of plantar-flexion velocity and variation of dorsiflexion velocity best represented the clinical toe-tapping score (r = 0.72-0.81). All clinical scores showed better correlation with velocity than with amplitude, and velocity was more affected (dispersed from the performance of controls) than amplitude. Movement directions had a slight effect on the results; specifically, the magnitude measures better correlated during plantar flexion and the variation measure better correlated during dorsiflexion. CONCLUSION: The suggested measures represented clinical scores well and are expected to be helpful in clinical diagnosis of lower limb bradykinesia. Possible dissociations of amplitude and speed impairments and of movement directions in PD deserve further investigation.

Toothbrushing region detection using three-axis accelerometer and magnetic sensor.

Due to the possible occurrence of periodontal disease at an early age, it is important to have proper toothbrushing habits as early as possible. With this aim, the feasibility and concept of a smart toothbrush (ST) capable of tracing toothbrushing motion and orientation information was suggested. In this study, we proposed the advanced ST system and brushing region classification algorithm. In order to trace the brushing region and the orientation of a toothbrush in the mouth, we required the absolute coordinate information of ST. By using tilt-compensated azimuth (heading) algorithm, we found the inclination and orientation information of the toothbrush, and the orientation information while brushing inner tooth surfaces showed specific heading features that could be reliably discriminated from other brushing patterns. In order to evaluate the feasibility of clinical usage of the proposed ST, 16 brushing regions were investigated by 15 individual healthy subjects. The proposed ST system demonstrated 97.1%(±0.91) of the region detection accuracy and 15 brushing regions could be classified. This study also showed that the proposed ST system may be helpful for dental care personnel in patient education and instruction for oral hygiene regarding brushing habits.

Heart monitoring garments using textile electrodes for healthcare applications.

We measured the electrical activity signals of the heart through vital signs monitoring garments that have textile electrodes in conductive yarns while the subject is in stable and dynamic motion conditions. To measure the electrical activity signals of the heart during daily activities, four types of monitoring garment were proposed. Two experiments were carried out as follows: the first experiment sought to discover which garment led to the least displacement of the textile electrode from its originally intended location on the wearer's body. In the second, we measured and compared the electrical activity signals of the heart between the wearer's stable and dynamic motion states. The results indicated that the most appropriate type of garment sensing-wise was the "cross-type", and it seems to stabilize the electrode's position more effectively. The value of SNR of ECG signals for the "cross-type" garment is the highest. Compared to the "chest-belt-type" garment, which has already been marketed commercially, the "cross-type" garment was more efficient and suitable for heart activity monitoring.

SPECT Reconstruction with Sub-Sinogram Acquisitions.

Described herein are the advantages of using sub-sinograms for single photon emission computed tomography image reconstruction. A sub-sinogram is a sinogram acquired with an entire data acquisition protocol, but in a fraction of the total acquisition time. A total-sinogram is the summation of all sub-sinograms. Images can be reconstructed from the total-sinogram or from sub-sinograms and then be summed to produce the final image. For a linear reconstruction method such as the filtered backprojection algorithm, there is no advantage of using sub-sinograms. However, for nonlinear methods such as the maximum likelihood (ML) expectation maximization algorithm, the use of sub-sinograms can produce better results. The ML estimator is a random variable, and one ML reconstruction is one realization of the random variable. The ML solution is better obtained via the mean value of the random variable of the ML estimator. Sub-sinograms can provide many realizations of the ML estimator. We show that the use of sub-sinograms can produce better estimations for the ML solution than can the total-sinogram and can also reduce the statistical noise within iteratively reconstructed images.

Prioritizing problem features in Korean patients with senile dementia for implementation of monitoring technologies.

The purpose of this study was to investigate the central problem features of Korean patients with senile dementia and to prioritize the features according to risk to the patient with a view to the implementation of remote monitoring technologies. Twenty central problem features were extracted using factorial analysis. The frequency of violent language and confabulation, gathering, and repetition was significantly greater in female than in male patients with senile dementia. All central features, with the exception of abnormal sexual behavior and audiovisual deficits, differed in frequency between the normal elderly and the senile dementia patients and between patients with dementias of different severity. Judgment disorder was the greatest differentiating factor between the normal elderly and the patients with senile dementia. For dementia severity, memory disorder was the greatest differentiating factor of severe versus mild dementia. When risk to the patient was analyzed, problems of perception were identified as the problem features of highest priority.

Portable activity monitoring system for temporal parameters of gait cycles.

A portable and wireless activity monitoring system was developed for the estimation of temporal gait parameters. The new system was built using three-axis accelerometers to automatically detect walking steps with various walking speeds. The accuracy of walking step-peak detection algorithm was assessed by using a running machine with variable speeds. To assess the consistency of gait parameter analysis system, estimated parameters, such as heel-contact and toe-off time based on accelerometers and footswitches were compared for consecutive 20 steps from 19 individual healthy subjects. Accelerometers and footswitches had high consistency in the temporal gait parameters. The stance, swing, single-limb support, and double-limb support time of gait cycle revealed ICCs values of 0.95, 0.93, 0.86, and 0.75 on the right and 0.96, 0.86, 0.93, 0.84 on the left, respectively. And the walking step-peak detection accuracy was 99.15% (±0.007) for the proposed method compared to 87.48% (±0.033) for a pedometer. Therefore, the proposed activity monitoring system proved to be a reliable and useful tool for identification of temporal gait parameters and walking pattern classification.

Real-time elderly activity monitoring system based on a tri-axial accelerometer.

PURPOSE: The purpose of this study is to develop an automatic human movement classification system for the elderly using single waist-mounted tri-axial accelerometer. METHODS: Real-time movement classification algorithm was developed using a hierarchical binary tree, which can classify activities of daily living into four general states: (1) resting state such as sitting, lying, and standing; (2) locomotion state such as walking and running; (3) emergency state such as fall and (4) transition state such as sit to stand, stand to sit, stand to lie, lie to stand, sit to lie, and lie to sit. To evaluate the proposed algorithm, experiments were performed on five healthy young subjects with several activities, such as falls, walking, running, etc. RESULTS: The results of experiment showed that successful detection rate of the system for all activities were about 96%. To evaluate long-term monitoring, 3 h experiment in home environment was performed on one healthy subject and 98% of the movement was successfully classified. CONCLUSIONS: The results of experiment showed a possible use of this system which can monitor and classify the activities of daily living. For further improvement of the system, it is necessary to include more detailed classification algorithm to distinguish several daily activities.

Interactive toothbrushing education by a smart toothbrush system via 3D visualization.

The very first step for keeping good dental hygiene is to employ the correct toothbrushing style. Due to the possible occurrence of periodontal disease at an early age, it is critical to begin correct toothbrushing patterns as early as possible. With this aim, we proposed a novel toothbrush monitoring and training system to interactively educate on toothbrushing behavior in terms of the correct brushing motion and grip axis orientation. Our intelligent toothbrush monitoring system first senses a user's brushing pattern by analyzing the waveforms acquired from a built-in accelerometer and magnetic sensor. To discern the inappropriate toothbrushing style, a real-time interactive three dimensional display system, based on an OpenGL 3D surface rendering scheme, is applied to visualize a subject's brushing patterns and subsequently advise on the correct brushing method.

Reusable electrical activity of the heart monitoring patch for mobile/ubiquitous healthcare.

In order to monitor electrical activity of the heart during daily life, we present an electrode of a medical instrument system which is able to measure the body surface potential difference by minimizing the electrode distance. The designed electrode is composed of concentric circles. It was made from the basis of the Laplacian equation, and implemented on PCB coated with gold. So that it does not cause the uncomfortable feeling of contact and possible skin troubles which are typical shortcoming of the conventional ECG measurement. The suggested method utilized three concentric circles on FR-4 substrate, so new amplifier design regarding measuring of small biological signal, is considered which has the characteristics of asymmetric input impedance since the area of concentric circular ring electrodes is not identical. Thereby, electrical activity of the heart was obtained successfully. However, its signal quality is a little bit degraded and the motion artifact still remains as a major problem as is in conventional electrocardiography measurement. Certainly stable measurement setup was needed to reduce the motion artifact originated from variation in static electricity between skin and electrode interfaces.

Application for the wearable heart activity monitoring system: analysis of the autonomic function of HRV.

The wearable patch-style heart activity monitoring system (HAMS) which was used for recording ECG signal in this study is self-developed. This electrode design helps the non-restricted, non-aware and non-invasive ECG measurement. The modified bipolar electrode is convenient in use because it is designed for easy attachment and detachment with ECG measuring module by snap button. Besides, it minimizes EMI by removing the cables. In the same subjects who were exposed under stress and non-stress, the questionnaire was given out, the amount of the stress hormone was measured by blood test and the ECG signal was recorded. Through the analysis of ECG signal which is measured with wearable patch-style HAMS, the parameter highly related with mental stress were extracted from frequency and time domain. These parameters were certified as the meaningful factor after correlation analysis on the results from questionnaire and stress hormone test. Also, it is proved that the availability of wearable patch-style heart monitoring system is efficient as health monitoring system in any places and occasion.

Wearable accelerometer system for measuring the temporal parameters of gait.

A small and wireless accelerometer system was developed for the estimation of temporal gait parameters. The new system was built using two 3-axis accelerometers. Measurement's accuracy was assessed using as a criterion standard provided by foot switches. To assess the consistency of this system, estimates of heel contact and toe off time based on accelerometers and those based on footswitches were compared for 20 steps from 8 individual healthy subjects. Accelerometers and footswitches had high consistency in the temporal gait parameters. The stance, swing, single support, and double support time of gait cycle revealed ICCs values of 0.95, 0.93, 0.86, and 0.75 on the right and 0.96, 0.86, 0.93, 0.84 on the left, respectively. Therefore, this system proved to be a reliable tool for identification of temporal gait parameters.