Development and Validation of Mechanically Compliant Wearable Monitoring Systems for Swallowing Function and Disorders
Phase: EARLY_PHASE1
Conditions: Deglutition Disorders
Sponsor: Purdue University

 
 
 
Title of study 
Wearable Monitoring Systems for Swallowing Function and Disorders 
 
NCT # 
NCT04243577 
 
Latest Approval Date 
10/18/2023 
 
 
 
 
Study Protocol & Statistical Analysis Plan 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

STUDY PROTOCOL 
 
Objective 
Wearable tele-rehabilitation technology allows for the efficient provision of rehabilitation services 
from a distance, facilitating tele-management of many disorders. The proposed research aimed 
to develop and validate a mechanically compliant, easy-to-use, and inexpensive wearable tele-
monitoring system, for future use in the rehabilitation of swallowing disorders (dysphagia). The 
hypothesis was that the newly developed surface electromyographic (sEMG) wearable sensors 
would have equal or better performance than traditional wired sEMG sensors used today in 
clinical practice. Factors related to signal quality and patient reported outcomes (e.g., 
satisfaction/comfort level, adverse effects etc.) were examined. 
 
Design and Devices 
This study is a within subject randomized cross-over design study. Two iterations of a wearable 
surface EMG sensors patch we developed were tested against commercially available wired 
devices. The first iteration of the wearable sensor patch was an ultrathin patch with a 
honeycomb-inspired design that included sEMG and strain sensors in order to capture muscle 
activity and thyroid movement signals from the submental area during swallows and swallow 
maneuvers/exercises. The second iteration was a more durable slightly thicker flexible, non-
stretchable, and double-sided thin patch. The exact same methods were used to test both 
iterations against commercially available conventional sensors. For both iterations’ testing, the 
order of the experimental conditions differed across groups. Group A participants completed the 
experimental protocol with the conventional electrodes first, and Group B participants completed 
the protocol with the experimental patch first. There was a 10-min rest period between the two 
experimental conditions. 
The first iteration testing was completed in 40 healthy older adults. Results revealed technical 
improvements were needed and therefore a second improved version of the sensor was then 
developed. The second iteration testing was done in an additional sample of 30 healthy older 
adults. A total of 70 healthy older participants were included in the study. 
 
Methods 
Participants 
Healthy older adults 50-85 years old (the typical age range of our target clinical population for 
future studies) were recruited in this study. Inclusion criteria were: 1) no history of dysphagia, 2) 
no history of neurological disease, head/neck cancer, radiation or surgery, 3) a score in the 
normal/mild range on the Montreal Cognitive Assessment (MoCA), and 4) a score of <3 on the 
Eating Assessment Tool (EAT-10; a self-report screening for dysphagia). Exclusion criteria were: 
1) history of dysphagia; 2) history of neurological disease, head/neck cancer, radiation or 
surgery, 3) a score in moderate-severe range on MoCA, and 4) a score of >2 on the EAT-10.  
 
Instrumentation Validation – Data Collection 
For each iteration of the device, a group of participants was tested using the experimental 
device/sensors and the commercially available ones in counterbalanced order. Results were 
analyzed to allow design improvements before the next iteration was developed and tested.  
To validate each of the two iterations of the newly developed sEMG patch, we used wired 
electrodes (e.g., AED Brands, A snap-style pad) connected to a commercially available wireless 
amplifier (BioRadio, GLNeuroTech Inc.), as the comparison system. During this experiment, the 
electrodes were placed on the submental muscles (under the chin). The sEMG signals were 
sampled while subjects remained as still as possible and sat upright with the head in neutral 

position. Participants were asked to complete several types of swallows multiple times. Each set 
of tasks was tested with one type of device first (conventional or experimental) and was 
repeated 10 min after the first set with the other type of device. For both types of devices, 
swallows were confirmed via a nasal airflow cannula to detect the swallow apnea (nasal airflow 
cessation), and an observer’s button that was be pressed at swallow completion.  
 
Outcome Measures and Data Analysis 
Primary Outcome Variables – Signal Quality parameters 
Signal quality outcomes tested across both iterations’ tests included normalized task-related 
EMG amplitude (primary outcome), and signal to noise (S/N) ratio. Because task sEMG 
amplitudes vary among subjects (e.g., as a function of electrode impedance), we expressed 
amplitude in microvolts and normalized these values within subjects. For normalization, 
participants produce 3 trials of maximum lingual press, and we expressed the task-related EMG 
amplitudes as percentages of the amplitude of this criterion gesture. For analysis, research 
assistants blinded to sensor type conducted analyses using a custom MATLAB script. 
 
Secondary Outcome Variables – Preclinical parameters 
We examined adverse effects and safety by thoroughly inspecting participants’ submandibular 
skin before and after each experiment. Specifically, we documented the incidence of skin 
irritations in the subjects. A visual inspection form including a binary scale (YES/NO) was 
devised by the investigators (no formal name) and was used by a rater who thoroughly 
inspected the participants’ submandibular skin before and after each experiment. For any 
irritation or change in appearance YES was selected and the type of irritation was descriptively 
recorded (e.g., red skin). This form was completed by a rater who was not part of the data 
collection process and who was blinded to sensors type to avoid any bias. The number of YESs 
were used to calculate the incidence of these adverse effects in the sample. This inspection was 
completed immediately after removal of each sensor type and 5 minutes later as well. 
Ease-of-use/comfort was examined using a survey (using a positive centered 5-point 
Likert scale) with questions about ease-of-use/comfort after each experiment with each device. 
This survey included statements related to the participants’ ease-of-use/comfort during the 
experimental protocol (e.g., I was comfortable while the experimenter placed the sensors on my 
skin). The answers were rated on a 10-point scale (i.e., 1 = extremely uncomfortable, 10 = 
extremely comfortable). Higher values indicated better or higher satisfaction/ comfort scores. 
Total scores were compared across conditions/devices tested. 
 
 
STATISTICAL ANALYSIS PLAN 
 
The study was designed to have at least 80% power to detect a difference in the primary 
variables of interest, that is, SNR, and normalized mean amplitude of swallow trials. The sample 
size was determined via a power analysis based on pilot results. Alpha level was set to .025 to 
correct for multiple comparisons. Quantile–quantile plots and the Shapiro–Wilk test was also 
used to assess normality. For S/N ratio comparisons non-inferiority tests were used for both 
iterations’ testing. For the normalized amplitude data, equivalency testing was used for both 
iterations’ testing. Margins for these tests were calculated using our preliminary data acquired 
with the conventional electrodes, which were considered as the current gold standard. 
Descriptive statistics (frequency counts) were used to report adverse effects (skin related 
effects). Paired t tests were used to test for differences in satisfaction/comfort level.