Textile-based Wearable to Monitor Heart Activity in Paediatric Population: A Pilot Study

Background

Cardiac monitoring for children with heart disease still employs common clinical techniques that require visits to hospital either in an ambulatory or inpatient setting. Frequent cardiac monitoring, such as heart rate monitoring, can limit children's physical activity and quality of life. The main objective of this study is to evaluate the performance of a textile-based device (SKIIN) in measuring heart rate (HR) in different tasks: lying down, sitting, standing, exercising, and cooling down.

Methods

Twenty participants including healthy children and children with heart disease were included in this study. The difference between the HRs recorded by the SKIIN was compared with a reference electrocardiogram collection by normalized root mean squared error. Participants completed a questionnaire on their experience wearing the textile device with additional parental feedback on the textile device collected.

Results

Participants had the median age of 14 years (range: 10-17 years), with body mass index 23.1 ± 3.8 kg/m2 and body surface area 1.70 ± 0.25 m2. The HR recorded by SKIIN and reference system significantly changes between tasks (P < 0.001), while not significantly different from each other (P > 0.05). The normalized root mean squared error was 3.8% ± 3.0% and 3.6% ± 3.7% for healthy and the heart disease groups, respectively. All participants found the textile device non-irritating and easy to wear.

Conclusions

This study provides proof of concept that HR can be robustly and conveniently monitored by smart textiles, with similar accuracy to standard-of-care devices.

Exploring textile-based electrode materials for electromyography smart garments

Introduction

In recent years, electromyography (EMG) has been increasingly studied for wearable applications. Conventional gel electrodes for electrophysiological recordings have limited use in everyday applications such as prosthetic control or muscular therapy at home. This study investigates the efficacy and feasibility of dry-contact electrode materials employed in smart textiles for EMG recordings.

Methods

Dry-contact electrode materials were selected and implemented on textile substrates. Using these electrodes, EMG was recorded from the forearm of able-bodied subjects. 25% and 50% isometric maximum voluntary contractions were captured. A comparative investigation was performed against gel electrodes, assessing the effect of material properties on signal fidelity and strength compared.

Results

When isolating for electrode surface area and pressure, 31 of the 40 materials demonstrated strong positive correlations in their mean PSD with gel electrodes (r > 95, p < 0.001). The inclusion of ionic liquids in the material composition, and using raised or flat electrodes, did not demonstrate a significant effect in signal quality.

Conclusions

For EMG dry-contact electrodes, comparing the performance against gel electrodes for the application with the selected material is important. Other factors recommended to be studied are electrodes’ durability and long-term stability.

Feasibility and significance of stimulating interscapular muscles using transcutaneous functional electrical stimulation in able-bodied individuals

OBJECTIVE

The study objective was to assess the feasibility of stimulating the lower trapezius (LT), the upper trapezius (UT) and serratus anterior (SA) muscles along with anterior or middle deltoid, using surface functional electrical stimulation (FES). The secondary aim was to understand the effects of LT, UT, and SA stimulation on maximum arm reach achieved in shoulder flexion and abduction.

DESIGN

Single arm interventional study.

SETTING

Inpatient Rehabilitation Hospital.

PARTICIPANTS

Ten healthy volunteers.

INTERVENTION

Participants completed 10 trials for each of the 3 conditions in flexion and abduction, i.e. (1) Active voluntary flexion or abduction, (2) FES for anterior deltoid for flexion or middle deltoid for abduction, and (3) FES for LT, UT, and SA along with anterior deltoid for flexion or middle deltoid for abduction.

OUTCOME MEASURES

Maximum arm reach and percent angle relative to the voluntary movement were computed from motion capture data for each condition. Wilcoxon signed-rank test was used to compare the maximum reach between two FES conditions.

RESULTS

The study results showed that all three interscapular muscles can be stimulated using surface FES. Maximum reach in abduction was greater for FES of middle deltoid along with the interscapular muscles (51.77° ± 17.54°) compared to FES for middle deltoid alone (43.76° ± 15.32°; Z = -2.701, P = 0.007). Maximum reach in flexion for FES of anterior deltoid, along with interscapular muscles, was similar to that during FES of anterior deltoid alone.

CONCLUSION

Interscapular muscles can be stimulated using surface FES devices and should be engaged during rehabilitation as appropriate.

Evaluation of dry textile electrodes for long-term electrocardiographic monitoring

Background

Continuous long-term electrocardiography monitoring has been increasingly recognized for early diagnosis and management of different types of cardiovascular diseases. To find an alternative to Ag/AgCl gel electrodes that are improper for this application scenario, many efforts have been undertaken to develop novel flexible dry textile electrodes integrated into the everyday garments. With significant progresses made to address the potential issues (e.g., low signal-to-noise ratio, high skin–electrode impedance, motion artifact, and low durability), the lack of standard evaluation procedure hinders the further development of dry electrodes (mainly the design and optimization).

Results

A standard testing procedure and framework for skin–electrode impedance measurement is demonstrated for the development of novel dry textile electrodes. Different representative electrode materials have been screen-printed on textile substrates. To verify the performance of dry textile electrodes, impedance measurements are conducted on an agar skin model using a universal setup with consistent frequency and pressure. In addition, they are demonstrated for ECG signals acquisition, in comparison to those obtained using conventional gel electrodes.

Conclusions

Dry textile electrodes demonstrated similar impedance when in raised or flat structures. The tested pressure variations had an insignificant impact on electrode impedance. Looking at the effect of impedance on ECG signals, a noticeable effect on ECG signal performance metrics was not observed. Therefore, it is suggested that impedance alone is possibly not the primary indicator of signal quality. As well, the developed methods can also serve as useful guidelines for future textile dry-electrode design and testing for practical ECG monitoring applications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12938-021-00905-4.

Functional Electrical Stimulation Therapy for Retraining Reaching and Grasping After Spinal Cord Injury and Stroke

Neurological conditions like hemiplegia following stroke or tetraplegia following spinal cord injury, result in a massive compromise in motor function. Each of the two conditions can leave individuals dependent on caregivers for the rest of their lives. Once medically stable, rehabilitation is the main stay of treatment. This article will address rehabilitation of upper extremity function. It is long known that moving the affected limb is crucial to recovery following any kind of injury. Overtime, it has also been established that just moving the affected extremities does not suffice, and that the movements have to involve patient’s participation, be as close to physiologic movements as possible, and should ideally stimulate the entire neuromuscular circuitry involved in producing the desired movement. For over four decades now, functional electrical stimulation (FES) is being used to either replace or retrain function. The FES therapy discussed in this article has been used to retrain upper extremity function for over 15 years. Published data of pilot studies and randomized control trials show that FES therapy produces significant changes in arm and hand function. There are specific principles of the FES therapy as applied in our studies: (i) stimulation is applied using surface stimulation electrodes, (ii) there is minimum to virtually no pain during application, (iii) each session lasts no more than 45–60 min, (iv) the technology is quite robust and can make up for specificity to a certain extent, and (v) fine motor function like two finger precision grip can be trained (i.e., thumb and index finger tip to tip pinch). The FES therapy protocols can be successfully applied to individuals with paralysis resulting from stroke or spinal cord injury.

Functional electrical stimulation of the facial muscles to improve symptoms in individuals with major depressive disorder: pilot feasibility study

Background

Currently, the mainstay of treatment in patients diagnosed with major depressive disorder (MDD) requiring medical attention is second generation anti-depressants. However, about 40% of patients treated with second-generation anti-depressants do not respond to initial treatment and approximately 70% do not achieve remission during the first-step treatment. There are a few non-pharmacological options available, but none have shown consistently positive results. There is a need for an intervention that is relatively easy to administer, produces consistently positive results and is associated with minimal side effects. In the current study, we assessed the feasibility of using transcutaneous Functional Electrical Stimulation Therapy (FEST) of the facial muscles, as a tool for improving depressive symptoms in individuals with MDD.

Results

Ten (10) individuals with moderate to severe MDD received three FEST sessions/week for a minimum of 10 to a maximum of 40 sessions. All study participants completed the required 10 therapy sessions, and 5 of the 10 participants completed additional 30 (totalling 40) FEST sessions. There were no adverse events or concerns regarding compliance to therapy. We found statistically significant improvements on Hamilton Rating Scale for Depression (HDS) and Inventory of Depressive Symptomatology (IDS) measures. However, no significant improvements were found on Positive and Negative Affect Scale and 10-point Visual Analogue Scale scales. Participants reported improvements in sleeping patterns, and this correlated with statistically significant improvements on sleep parameters of HDS and IDS measures.

Conclusion

This study indicates that facial FEST is an acceptable, practical, and safe treatment in individuals with MDD. We provide preliminary evidence to show improvements in depressive symptoms following a minimum of 10 FEST sessions.

End-user and clinician perspectives on the viability of wearable functional electrical stimulation garments after stroke and spinal cord injury

PURPOSE

Functional electrical stimulation (FES), through repetitive training (FES-therapy) or continuous assistance (neuro-prosthesis), can restore motor function after paralysis due to spinal cord injury or stroke. With current technology, patients are often incapable of independently applying FES, thereby limiting its use. Novel FES-garments with embedded stimulation electrodes were developed in collaboration with Myant, Canada, to address this problem. The purpose of this study was to collect the views of future end-users to inform the refinement of the device design and to obtain insights on subsequent commercialization of this rehabilitation and assistive technology.

METHODS

A qualitative study was undertaken to determine the needs of potential users (patients and clinicians; n = 19). Participant took part in interviews or focus groups after a presentation of the garments. An inductive content analysis was used to generate the themes from the data and identify data saturation.

RESULTS

The identified themes and sub-themes were: (1) User Perspectives: users' characteristics (needs, limitations), expected benefits (beliefs), and anticipated problems (fears); (2) Device Design: technical features, usability, and disadvantages of the garment, cables, stimulator, software, and interface; (3) Acquisition Process: organizational procedures (acquisition and adoption steps); and (4) Business Model: financial and strategic aspects to facilitate commercialization and support users.

CONCLUSIONS

The insights obtained from end-users and clinicians provide guidelines to optimize the development of novel FES-garments, and strategies for bringing the device to the market. The themes identified can serve to inform other rehabilitation and assistive technology developers with processes and ideas on how to meet these groups' needs.IMPLICATIONS FOR REHABILITATIONParticipants with neurological paralysis have interest and critical views on new rehabilitation and assistive technology, and the repercussions of using new technologies to address their function, health and wellbeing.The FES-garment design presented appeared acceptable to the end-users, pending resolution of certain shortcomings (wiring, operating duration, robustness, easiness to don and doff).End-users and clinicians had specific views regarding the acquisition process of new technologies (training, customization, and follow-up/support), which are important to take into consideration to ensure broad stakeholders uptake.

Lessons learned from the pilot study of an orthostatic hypotension intervention in the subacute phase following spinal cord injury

Context: Following spinal cord injury (SCI) at the cervical or upper-thoracic level, orthostatic hypotension (OH) is observed in 13-100% of patients. This study aimed to test the feasibility of conducting a randomized controlled trial combining a dynamic tilt-table (Erigo^®) and functional electrical stimulation (FES) to mitigate OH symptoms in the subacute phase after SCI. Design: Pilot study. Setting: A tertiary rehabilitation hospital. Participants: Inpatients who had a C4-T6 SCI (AIS A-D) less than 12 weeks before recruitment, and reported symptoms of OH in their medical chart. Interventions: Screening sit-up test to determine eligibility, then 1 assessment session and 3 intervention sessions with Erigo^® and FES for eligible participants. Outcome measures: Recruitment rate, duration of assessment and interventions, resources used, blood pressure, and Calgary Presyncope Form (OH symptoms). Results: Amongst the 232 admissions, 148 inpatient charts were reviewed, 11 inpatients met all inclusion criteria, 7 participated in a screening sit-up test, and 2 exhibited OH. Neither of the two participants recruited in the pilot study was able to fully complete the assessment and intervention sessions due to scheduling issues (i.e. limited available time). Conclusion: This pilot study evidenced the non-feasibility of the clinical trial as originally designed, due to the low recruitment rate and the lack of available time for research in participant's weekday schedule. OH in the subacute phase after SCI was less prevalent and less incapacitating than expected. Conventional management and spontaneous resolution of symptoms appeared sufficient to mitigate OH in most patients with subacute SCI.

Garments for functional electrical stimulation: Design and proofs of concept

Introduction

Repeated use of functional electrical stimulation can promote functional recovery in individuals with neurological paralysis. We designed garments able to deliver functional electrical stimulation.

Methods

Shirts and pants containing electrodes knitted with a conductive yarn were produced. Electrodes were moistened with water before use. Stimulation intensity at four thresholds levels (sensory, movement, full range of motion, and maximal), stimulation comfort, and electrical properties of the interface were tested in one able-bodied subject with garment electrodes and size-matched conventional gel electrodes. The pants and shirt were then used to explore usability and design limitations.

Results

Compared to gel electrodes, fabric electrodes had a lower sensory threshold (on forearm muscles) but they had a higher maximal stimulation threshold (for all tested muscles). The stimulation delivery was comfortable when the garment electrodes were recently moistened; however, as the electrodes dried (within 9 to 18 min) stimulation became unpleasant. Inconsistent water content in the fabric electrodes caused inconsistent intensity thresholds and inconsistent voltage necessary to apply a desired stimulation current. Garments’ tightness and impracticality of electrode lead necessitate further design improvement.

Conclusions

Fabric electrodes offer a promising alternative to gel electrodes. Further work involving people with paralysis is required to overcome the identified challenges.

A new method to assess temporal features of gait initiation with a single force plate

The aim of this study was to investigate whether time of toe-off and heel-contact during gait initiation could be assessed with a single force plate. Twenty subjects performed ten self-paced gait initiations and seven other subjects performed ten gait initiations in four new conditions (slow, fast, obstacle and splint). Several force-plate parameters were measured with a single force plate, and actual toe-off and heel-contact were assessed with a motion analysis system. Results showed strong temporal correlations and closeness (r=.86-.99, mean error=3-86 ms) between two force-plate parameters and the kinematics events (toe-off and heel-contact). These new parameters may be of interest to easily measure duration of anticipatory postural adjustments and swing phase during clinical assessments.

Does the new Helix 3D hip joint improve walking of hip disarticulated amputees?

PURPOSE

Testing the new hip joint Helix3D efficiency through clinical data and walking parameters.

METHOD

Three young hip-disarticulated patients (P1, P2 and P3) were assessed both with their previous prosthesis at first day, then four days and six months after being trained with a new prosthesis equipped with the Helix3D hip joint. Assessments comprised a satisfaction questionnaire, a two-minute walk test and a recording of main spatiotemporal gait parameters

RESULTS

After four days with the Helix3D, the satisfaction for the prosthesis was improved for P1, unchanged for P2 and reduced for P3. Distance walked during two minutes increased for P1, unchanged for P2 and slightly improved for P3. Gait pattern was improved in P1, only. P1 abandoned the Helix3D at six months due to an ischiatic wound. P2 and P3 chose not to use the Helix at the end of the four days training period because they could not adapt to the Helix3D characteristics (hydraulic control of hip extension and assistance to hip flexion) and because they did not gain enough benefits. Despite much effort to adjust the prosthesis, the three patients definitively abandoned the Helix3D because of comfort problems, and decided to walk with their previous prosthesis equipped with a monocentric hip joint or even with crutches only.

CONCLUSION

The Helix3D hip joint may need further developments to get clinically relevant for hip-disarticulated amputees who may also need a long training period to adapt to its technical characteristics.

Superimposed electrical stimulation comfortably improves the endurance of maximal voluntary contractions

AIM

Electrical stimulation has shown to improve muscle endurance in sub-maximal contractions but sessions were painful due to the electric stimuli parameters. Therefore, the present study tested the effects of the superimposed electrical stimulation technique using comfortable current on endurance in repetitions of maximal voluntary contraction.

METHODS

Seventeen young healthy subjects performed fifty maximal voluntary contractions of the triceps brachii in two conditions of contraction (voluntary vs. voluntary + superimposed electrical stimulation).

RESULTS

Peak force and force-time integral were consistently decreased in the voluntary muscular contraction condition after the 20th - 30th trials whereas they were maintained in the superimposed electrical stimulation condition (P<0.05) until the end of the fifty trials.

CONCLUSION

The superimposition of neuromuscular electrical stimulation extends the muscle ability to repeat maximal voluntary contractions. The present results also evidenced the ability of the superimposed electrical stimulation technique to make the mechanisms of muscle central fatigue inefficient.