Changes In Bioimpedance Research Articles

New derivation method and simulation of skin effect in biological tissue.

Based on the electrical properties of biological tissues, bioimpedance measurement technology can be employed to collect physiologic and pathologic information by measuring changes in human bioimpedance. When an alternating current (AC) is applied as a detection signal to a tissue, the current field distribution, which is affected by skin effect, is related to both the bioimpedance of the tissue and the AC frequency. These relations would possibly reduce the accuracy and reliability of the measurement. In this study, an electromagnetic theory-based method, in which cylindrical conductor were divided into layers, was used to obtain current field distribution models of human limbs. Model simulations were conducted in MATLAB. The skin effect phenomenon and its characteristics in human tissues at different frequencies were observed, thus providing essential data on skin effect, which are useful in the development of bioimpedance measurement technology.

A Temperature-Based Bioimpedance Correction for Water Loss Estimation During Sports.

The amount of total body water (TBW) can be estimated based on bioimpedance measurements of the human body. In sports, TBW estimations are of importance because mild water losses can impair muscular strength and aerobic endurance. Severe water losses can even be life threatening. TBW estimations based on bioimpedance, however, fail during sports because the increased body temperature corrupts bioimpedance measurements. Therefore, this paper proposes a machine learning method that eliminates the effects of increased temperature on bioimpedance and, consequently, reveals the changes in bioimpedance that are due to TBW loss. This is facilitated by utilizing changes in skin and core temperature. The method was evaluated in a study in which bioimpedance, temperature, and TBW loss were recorded every 15 min during a 2-h running workout. The evaluation demonstrated that the proposed method is able to reduce the error of TBW loss estimation by up to 71%, compared to the state of art. In the future, the proposed method in combination with portable bioimpedance devices might facilitate the development of wearable systems for continuous and noninvasive TBW loss monitoring during sports.

An intelligent control framework for robot-aided resistance training using hybrid system modeling and impedance estimation.

This study presents a novel therapy control method for robot-assisted resistance training using the hybrid system modeling technology and the estimated patient's bio-impedance changes. A new intelligent control framework based on hybrid system theory is developed, to automatically generate the desired resistive force and to make accommodating emergency behavior, when monitoring the changes of the impaired limb's muscle strength or the unpredictable safety-related occurrences during the execution of the training task. The impaired limb's muscle strength progress is online evaluated using its bio-damping and bio-stiffness estimation results. The proposed method is verified with a custom constructed therapeutic robot system featuring a Barrett WAM™ compliant manipulator. A typical inpatient stroke subject was recruited and enrolled in a ten-week resistance training program. Preliminary results show that the proposed therapeutic strategy can enhance the impaired limb's muscle strength and has practicability for robot-aided rehabilitation training.

The feasibility of using compression bioimpedance measurements to quantify peripheral edema

Abstract The accurate assessment of body fluid volume is important in many clinical situations, especially in the determination of “dry weight” in a dialysis setting. Currently, no clinically applicable diagnostic system exists to determine the mechanical properties that accurately characterize peripheral edema in an objective and quantitative manner. We have developed a method for quantifying the impact of compression on the electrical properties of tissue by measuring stress-induced changes in bioimpedance (BIS). Using this method, we simultaneously measured the impedance and mechanical response of a tissue mimicking material (tofu) under both quasi-static and dynamic loading conditions. Our results demonstrate a temporal quantification of viscoelastic properties using a viscoelastic phantom tissue model.

자세에 따른 생체임피던스 변화와 혈압 특성 분석

Bioelectrical Impedance Analysis(BIA) is a widely used method for estimating body composition changes which is a non-invasive, inexpensive, safety and reproductive method. We studied the bioimpedance change and the distinction of blood pressure according to body posture and conducted three kinds of experiments: the real-time bioimpedance measurement, the simulation using equivalent circuit model and the blood pressure measurement. Bioimpedance is measured during 4 minutes at the multi-frequency(1 kHz, 10 kHz, 20 kHz, 50 kHz, 70 kHz, 100 kHz). From the experiment results, the changes in body postures result in changes of resistance and reactance, with an average rapid increase of body impedance when going from standing, sitting to supine. Specially, the laying resistance on average was 16.49% higher than supine resistance at 50 kHz and the laying reactance measurement was also 26.05% higher than sitting reactance at 1 kHz. Blood pressure in standing posture was higher than those in other postures both in maximum() and in minimum(). The results of BIA and blood pressure in this study will be contributed to the research on acute illness, extreme fat, and body shape abnormalities.

Continuous noninvasive cardiac output in children: is this the next generation of operating room monitors? Initial experience in 402 pediatric patients.

Electrical Cardiometry(™) (EC) estimates cardiac parameters by measuring changes in thoracic electrical bioimpedance during the cardiac cycle. The ICON(®), using four electrocardiogram electrodes (EKG), estimates the maximum rate of change of impedance to peak aortic blood acceleration (based on the premise that red blood cells change from random orientation during diastole (high impedance) to an aligned state during systole (low impedance)). To determine whether continuous cardiac output (CO) data provide additional information to current anesthesia monitors that is useful to practitioners. After IRB approval and verbal consent, 402 children were enrolled. Data were uploaded to our anesthesia record at one-minute intervals. Ten-second measurements (averaged over the previous 20 heart beats) were downloaded to separate files for later comparison with routine OR monitors. Data from 374 were in the final cohort (loss of signal or improper lead placement); 292,012 measurements during 58,049 min of anesthesia were made in these children (1 day to 19 years and 1 to 107 kg). Four events had a ≥25% reduction in cardiac index at least 1 min before a clinically important change in other monitored parameters; 18 events in 14 children confirmed manifestations of other hemodynamic measures; eight events may have represented artifacts because the observed measurements did not seem to fit the clinical parameters of the other monitors; three other events documented decreased stroke index with extreme tachycardia. Electrical cardiometry provides real-time cardiovascular information regarding developing hemodynamic events and successfully tracked the rapid response to interventions in children of all sizes. Intervention decisions must be based on the combined data from all monitors and the clinical situation. Our experience suggests that this type of monitor may be an important addition to real-time hemodynamic monitoring.

Upper Extremity Vein Graft Monitoring Device after Surgery Procedure: A Preliminary Study

In most cases, surgical vein bypass or interposition vein grafting was used in both primary management of crush-avulsion amputations and on intervention for rehabilitating the patency of occluded arteries via microvascular surgery. However, surgical revascularization has significant shortcomings, principal among which is the high rate of accelerated thrombosis that develops in arterialised vein graft which renders the vein graft susceptible to acute occlusion and eventually give rise to graft failure. Evaluaion and detection of vein graft failure is essential as that will be the starting point for the clinician to make the diagnosis and safeguard patency of implanted vein graft which would otherwise fail. Unfortunately, most of the available diagnostic and monitoring tools available in the market are expensive, hence not all the hospital, private clinic and others medical centers that fully-equipped with these type of equipments. The objective of this study is to design and develop a low-cost and non-invasive vein graft monitoring prototype that able to provide high accuracy in predicting the vein graft patency and meanwhile providing the short-term monitoring on vein graft right after surgery procedure. Impedance plethysmography (IPG) was employed to measure pulsatile changes in longitudinal impedace to quantify arterial blood flow and pulsatile blood volume. Tetra-polar electrode measurement system was implemented by introduce a constant 1-mA AC current (I) at frequency of 100 kHz in the two outer electrodes. The voltage (V) is measured between the two inner electrodes, and the resulting impedance (Z) is calculated using Ohm’s Law. Arterial blood flow and pulsatile blood volume can then be estimated using impedance related volume conduction equation. By measuring the changes in electrical bioimpedance which can be used to derive important hemodynamic variables, it allows the postoperative graft surveillance and early detection atherosclerosis and thrombosis as well as estimate its severity that leads to the vein graft failure.

Comparison of the effects of the repetition rate between microsecond and nanosecond pulses: Electropermeabilization-induced electro-desensitization?

BackgroundApplications of cell electropermeabilization are rapidly growing but basic concepts are still unclear. In particular, the impact of electric pulse repetition rate in the efficiency of permeabilization has not yet been understood. MethodsThe impact of electric pulse repetition rate in the efficiency of permeabilization was analyzed in experiments performed on potato tissue and partially transposed on mice liver. On potato tissue, pulses with durations of 100μs or 10ns are applied. The intensity of permeabilization was quantified by means of bioimpedance changes and electric current measurements and a new index was defined. ResultsFor the two pulse durations tested, very low repetition rates (below 0.1Hz) are much more efficient to achieve cell permeabilization in potato tissue. In mice liver, using 100μs pulses, the influence of the repetition rate is more complex. Indeed, repetition rates of 1Hz and 10Hz are more efficient than 100Hz or 1kHz, but not the repetition rate of 0.1Hz for which there is an impact of the living mice organism response. ConclusionsWe propose that the effects reported here might be caused by an electroporation-induced cell membrane ‘electro-desensitization’ which requires seconds to dissipate due to membrane resealing. General significanceThis study not only reinforces previous observations, but moreover it sustains a new concept of ‘electro-desensitization’ which is the first unifying mechanism enabling to explain all the results obtained until now both in vitro and in vivo, with long and short pulses.

Bioimpedancemetry in the diagnostics of inflammatory process in the mammary gland.

The changes in mammary gland bioimpedance were examined in the dynamics of the inflammatory process. Bioimpedance of affected gland was 2-3-fold lower than that of the contralateral one; normally, this difference did not exceed 10%. The phases of inflammation development were paralleled by changes in bioimpedance. During wound epithelization, impedance increased and approximated the normal level. Further increase of bioimpedance by more than 30% and its stabilization at this level attested to recurrence of inflammation, while its irreversible drop indicated devitalization the tissues. The diagnostic criterion attesting to the development of local inflammatory reaction is deviation of bioimpedance in the impaired area by more than 15% from that of the adjacent intact site.

Prototype development of an electrical impedance based simultaneous respiratory and cardiac monitoring system for gated radiotherapy.

BackgroundIn radiotherapy, temporary translocations of the internal organs and tumor induced by respiratory and cardiac activities can undesirably lead to significantly lower radiation dose on the targeted tumor but more harmful radiation on surrounding healthy tissues. Respiratory and cardiac gated radiotherapy offers a potential solution for the treatment of tumors located in the upper thorax. The present study focuses on the design and development of simultaneous acquisition of respiratory and cardiac signal using electrical impedance technology for use in dual gated radiotherapy.MethodsAn electronic circuitry was developed for monitoring the bio-impedance change due to respiratory and cardiac motions and extracting the cardiogenic ECG signal. The system was analyzed in terms of reliability of signal acquisition, time delay, and functionality in a high energy radiation environment. The resulting signal of the system developed was also compared with the output of the commercially available Real-time Position Management™ (RPM) system in both time and frequency domains.ResultsThe results demonstrate that the bioimpedance-based method can potentially provide reliable tracking of respiratory and cardiac motion in humans, alternative to currently available methods. When compared with the RPM system, the impedance-based system developed in the present study shows similar output pattern but different sensitivities in monitoring different respiratory rates. The tracking of cardiac motion was more susceptible to interference from other sources than respiratory motion but also provided synchronous output compared with the ECG signal extracted. The proposed hardware-based implementation was observed to have a worst-case time delay of approximately 33 ms for respiratory monitoring and 45 ms for cardiac monitoring. No significant effect on the functionality of the system was observed when it was tested in a radiation environment with the electrode lead wires directly exposed to high-energy X-Rays.ConclusionThe developed system capable of rendering quality signals for tracking both respiratory and cardiac motions can potentially provide a solution for simultaneous dual-gated radiotherapy.

Abstract 18505: Determination of Non Invasive Cardiac Output by Electrical Cardiometry Technique in Acute Hemorrhagic Shock Model

Introduction: The non-invasive continuous determination of stroke volume (SV) in hypovolemic shock would be advantageous in pediatric intensive care. Electrical Cardiometry (EC) detects changes in thoracic bio-impedance and electrical conductivity of aortic blood flow allowing subsequent calculation of SV volumetric variables of preload, such as total end-diastolic volume index (TFC). The objective of this study was to evaluate the accuracy of EC when compared to trans esophageal echocardiogram (TEE) in hemorrhagic shock model. Hypothesis: SV calculated by EC would be similar to TEE in acute hemorrhagic shock model. Methods: Nine 3 month old pigglets (~25 Kg) were anesthetized and instrumented to measure heart rate, mean arterial pressure (MAP), SV. SV was measured using EC and TEE using Modified Simpson techniques. After baseline, celiac artery was transectected and ~ 50% of the blood volume was removed (hemorrhagic state), colloid infusion was administered at 10 mls/kg once MAP reached 35 mmHg (resuscitation state). TEE and EC was used to determine SV and TFC at baseline, hemorrhagic and resuscitation state. After evaluation of atrium and ventricular function the cardiologist also submitted a subjective score (0-50points) for pre-load (TPL) at the same time points. Where 0 is poor pre load and 50 is excessive pre load. SV and TPL vs TFC agreement was determined by Blant Altman. Results: Agreement was determined using Bland Altman analysis. 64 comparisons were made. SV correlation (r2= 0.74) was good between the 2 methods with a mean difference (bias) and precision of -0.8 and 0.85, respectively. TFC correlated well with TPL with bias 1.5 and limits of agreement -36 to 33%. Conclusions: EC technique is a viable method for measuring cardiac output in patients with acute hemorrhagic shock.

Gastric tissue damage analysis generated by ischemia: bioimpedance, confocal endomicroscopy, and light microscopy.

The gastric mucosa ischemic tissular damage plays an important role in critical care patients' outcome, because it is the first damaged tissue by compensatory mechanism during shock. The aim of the study is to relate bioimpedance changes with tissular damage level generated by ischemia by means of confocal endomicroscopy and light microscopy. Bioimpedance of the gastric mucosa and confocal images were obtained from Wistar male rats during basal and ischemia conditions. They were anesthetized, and stain was applied (fluorescein and/or acriflavine). The impedance spectroscopy catheter was inserted and then confocal endomicroscopy probe. After basal measurements and biopsy, hepatic and gastric arteries clamping induced ischemia. Finally, pyloric antrum tissue was preserved in buffered formaldehyde (10%) for histology processing using light microscopy. Confocal images were equalized, binarized, and boundary defined, and infiltrations were quantified. Impedance and infiltrations increased with ischemia showing significant changes between basal and ischemia conditions (P < 0.01). Light microscopy analysis allows detection of general alterations in cellular and tissular integrity, confirming gastric reactance and confocal images quantification increments obtained during ischemia.

Evaluation of different stimulation and measurement patterns based on internal electrode: Application in cardiac impedance tomography

The conductivity distribution around the thorax is altered during the cardiac cycle due to the blood perfusion, heart contraction and lung inflation. Previous studies showed that these bio-impedance changes are appropriate for non-invasive cardiac function imaging using Electrical Impedance Tomography (EIT) techniques. However, the spatial resolution is presently low. One of the main obstacles in cardiac imaging at the heart location is the large impedance variation of the lungs by respiration and muscles on the dorsal and posterior side of the body. In critical care units there is a potential to insert an internal electrode inside the esophagus directly behind the heart in the same plane of the external electrodes. The aim of the present study is to evaluate different current stimulation and measurement patterns with both external and internal electrodes. Analysis is performed with planar arrangement of 16 electrodes for a simulated 3D cylindrical tank and pig thorax model. In our study we evaluated current injection patterns consisting of adjacent, diagonal, trigonometric, and radial to the internal electrode. The performance of these arrangements was assessed using quantitative methods based on distinguishability, sensitivity and GREIT (Graz consensus Reconstruction algorithm for Electrical Impedance Tomography). Our evaluation shows that an internal electrode configuration based on the trigonometric injection patterns has better performance and improves pixel intensity of the small conductivity changes related to heart near 1.7 times in reconstructed images and also shows more stability with different levels of added noise. For the internal electrode, when we combined radial or adjacent injection with trigonometric injection pattern, we found an improvement in amplitude response. However, the combination of diagonal with trigonometric injection pattern deteriorated the shape deformation (correlation coefficient r=0.344) more than combination of radial and trigonometric injection (correlation coefficient r=0.836) for the perturbations in the area close to the center of the cylinder. We also find that trigonometric stimulation pattern performance is degraded in a realistic thorax model with anatomical asymmetry. For that reason we recommend using internal electrodes only for voltage measurements and as a reference electrode during trigonometric stimulation patterns in practical measurements.

Indices of malnutrition in patients admitted to general medical and chest medicine wards of an Iranian teaching hospital on admission and discharge

The nutritional status of hospitalised patients is generally poor on admission and in some cases declines during their stay in hospital. The aim of this study was to assess the nutritional status of a group of hospitalised patients on admission and at discharge from a large teaching hospital in Northwestern Iran. Male and female patients, who were anticipated to stay in hospital for more than 1 week on the general medical or chest medicine ward, gave informed consent to take part in the study. One hundred and fourteen patients (53.6 ± 17.2 years, body mass index (BMI) 21.0 ± 5.7 kg/m2 (mean ± standard error of the mean) were recruited to evaluate the nutritional status. Changes in bioimpedance and anthropometric markers of nutritional status were recorded. The NRS 2002 (nutritional risk screening) method was used to assess nutritional status in patients on admission and prior to discharge. Malnutrition, as assessed using NRS 2002 method, decreased during the stay of patients in hospital (2.8 ± 1.0 versus 1.8 ± 1.0, p < 0.001). This study showed that prevalence of malnutrition was as high as 63.1 % on admission to the general medical and chest wards. The nutritional status of patients was significantly changed over the period of their stay in hospital, as assessed using the NRS 2002 method, although patients lost weight due to the acute care situation.

Interference of silicone breast implants on bioimpedance measurement of body fat

No study targeting the impact of silicone breast implants on body composition measured by bioimpedance analysis was identified. Aiming to clarify this question a prospective clinical study was designed. Adult candidates were submitted to conventional analysis at baseline and two months after the surgical intervention. In addition, unwrapped prostheses were positioned in the axillary cavity before operation and bioimpedance was measured, both with and without application of ultrasound gel for improved conductivity (sham implantation). Patients (N = 20) were young and healthy (26.8 ± 3.6 years old, BMI 22.1 ± 3.7 kg/m(2)). In comparison with preoperative results, sham procedures pointed out increased body fat and body resistance (13.2 ± 5.6 vs 13.6 ± 5.4 kg, P = 0.017 and 523 ± 54 vs 569 ± 53 Ω, P = 0.003, respectively). Two-month follow-up confirmed the same pattern after surgical intervention, with minor discrepancies (13.2 ± 5.6 vs 13.8 ± 5.7 kg, P = 0.011 and 523 ± 54 vs 549 ± 62 Ω, P = 0.032, respectively). BMI remained stable and did not correlate with bioimpedance changes. Silicone was recognized as adipose tissue. Difference in total body fat (approximately 600 g) was consistent with used amount.

Comparison of Conductive Fabric Electrode With Electromyography to Evaluate Knee Joint Movement

This paper describes a conductive fabric electrode which includes much more surface area compared to an Ag/AgCl electrode using a bioimpedance measurement method and compares a conductive fabric electrode with electromyography to evaluate knee joint movement. Both bioimpedance changes and EMG from 15 subjects were reliable as their values exist within ±1.96 STD. The coefficient of variation from bioimpedance changes was 0.07 and the coefficient of variation from EMG was 0.33. As a result, for viewing in joint angles to estimate knee joint movements, a bioimpedance measurement method using a conductive fabric electrode was more sensitive than electromyography. In addition, a conductive fabric electrode is more effective to impedance changes than an Ag/AgCl electrode. Moreover, while an Ag/AgCl electrode cannot be used continuously, as the electrodes are designed to be disposable, a conductive fabric electrode is feasible for continuous use.

Monitoring Changes in Fluid Status With a Wireless Multisensor Monitor: Results From the Fluid Removal During Adherent Renal Monitoring (FARM) Study

Body fluid assessment is important for managing chronic kidney disease (CKD) and heart failure (HF). However, accurate detection of fluid retention remains elusive. The Fluid Removal During Adherent Renal Monitoring (FARM) study is a prospective, nonrandomized trial examining the performance of a wireless, noninvasive, multisensor fluid monitoring system, applied to the chest, to determine its performance and reliability during hemodialysis. Patients undergoing regular hemodialysis (n=25) were monitored continuously for 2 consecutive dialysis sessions and the interdialysis period. Physiologic variables, including tissue impedance, were recorded. The volume of fluid removed and weight change during dialysis were measured. An average of 3.4±1.2 L of fluid was removed during dialysis, which was associated with an increase in bioimpedance of 11.3±7.2 Ω. Change in bioimpedance was highly correlated with the amount of fluid removed but less so with weight loss. Normalized bioimpedance change (21.0%±12.1% increase from baseline, P<001) was larger than the normalized weight change (3.6%±1.1%, P<.01), suggesting a higher sensitivity and dynamic range than weight change for detecting fluid removal. The fluid monitoring system accurately tracked fluid and weight loss in patients during hemodialysis, supporting its use as a tool for the management of patient fluid status in disease states.

슬관절 운동 평가를 위한 생체 임피던스 측정용 전도성 섬유 센서의 여기 주파수별 특성 평가

This study describes a conductive fabric sensor and determines an optimum excitation frequency of the sensor to evaluate knee joint movements. Subjects were composed of 15 males (age: 30.7±5.3) with no known problems with their knee joints. The upper side of subjects’ lower limbs was divided into two areas and the lower side of subjects’ lower limbs was divided into three areas. The sensors were attached to 1 for 3 spot from a hip joint and to 3 for 4 spot from a knee joint which are the optimum conductive fabric sensor configuration to evaluate knee joint movements. As a result, the optimum excitation frequency for evaluating knee joint movements using conductive fabric sensors was 25 ㎑. Average and standard deviation of bio-impedance changes from 15 subjects were 92.1±137.2 Ω at 25 ㎑. The difference of bio-impedance changes between 25 ㎑ and 50 ㎑ was statistically significant (p＜0.05) and the difference of bio-impedance changes between 25 ㎑ and 100 ㎑ was also statistically significant (p＜0.001). These results showed that conductive fabric sensors are more sensitive to measure bio-impedance for evaluating knee joint movements as an excitation frequency decreases.

Bioimpedance Changes in Rats with CCl4-Induced Liver Fibrosis

To characterize the relationship between the stage of hepatic fibrosis and bioimpedance, several electric parameters were estimated in rats with <TEX>$CCl_4$</TEX>-induced liver fibrosis. Thirty three Sprague-Dawley rats were intraperitoneally injected with a <TEX>$CCl_4$</TEX>-mineral oil mixture (1:1, 0.2 mL/100 g) twice a week for 8 weeks. The resistance(R), reactance(X), impedance(Z), and dissipation factor(D) between 1 kHz and 100 kHz were then evaluated in the livers of the rats under pentobarbital anesthesia using an HP4294A Impedance Analyzer. The rats were killed 2, 4, 6, and 8 weeks later, and their livers were classified in accordance with Ishak's scoring system. R, X, and Z changed in accordance with the progression of hepatic fibrosis and the changes were greater at lower frequencies than at higher frequencies. In comparison, the D spectrum was biphasic; D increased initially then decreased with increasing frequency. All of the parameters(R, X, Z, and D) changed in accordance with the stage of fibrosis in the livers, but D changed specifically with the progression of fibrosis. These results indicate that hepatic fibrosis may be evaluated by determining the changes in D.

Optimum conductive fabric sensor sites for evaluating the status of knee joint movements using bio-impedance

BackgroundThere have been many studies that utilize the bio-impedance measurement method to analyze the movements of the upper and lower limbs. A fixed electrical current flows into the limbs through four standard disposable electrodes in this method. The current flows in the muscles and blood vessels, which have relatively low resistivity levels in the human body. This method is used to measure bio-impedance changes following volume changes of muscles and blood vessels around a knee joint. The result of the bio-impedance changes is used to evaluate the movements. However, the method using the standard disposable electrodes has a restriction related to its low bio-impedance changes: the standard disposable electrodes are only able to measure bio-impedance from a limited part of a muscle. Moreover, it is impossible to use continuously, as the electrodes are designed to be disposable. This paper describes a conductive fabric sensor (CFS) using a bio-impedance measurement method and determines the optimum configuration of the sensor for estimating knee joint movements.MethodsThe upper side of subjects' lower limbs was divided into two areas and the lower side of subjects' lower limbs was divided into three areas. The spots were matched and 6 pairs were selected. Subjects were composed of 15 males (age: 30.7 ± 5.3, weight: 69.8 ± 4.2 kg, and height: 173.5 ± 2.8 cm) with no known problems with their knee joints. Bio-impedance changes according to knee joint flexion/extension assessments were calculated and compared with bio-impedance changes by an ankle joint flexion/extension test (SNR I) and a hip joint flexion/extension test (SNR II).ResultsThe bio-impedance changes of the knee joint flexion/extension assessment were 35.4 ± 20.0 Ω on the (1, 5) pair. SNR I was 3.8 ± 8.4 and SNR II was 6.6 ± 7.9 on the (1, 5) pair.ConclusionsThe optimum conductive fabric sensor configuration for evaluating knee joint movements were represented by the (1, 5) pair.