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Cited by 209Non-Invasive Vital Sign MonitoringAdvanced Sensor and Energy Harvesting MaterialsSleep and related disorders

The DOI matches its Crossref record; 73 of the 75 references it cites were found in a registry or an index.

Recent advances in wearable sensors and portable electronics for sleep monitoring

Open access
Kwon, Shinjae, Kim, Hojoong, Yeo, Woon-Hong·2021·iScience
DOI 10.1016/j.isci.2021.102461PMC PMC8113882
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Abstract

Despite the increasing awareness of the importance of sleep, the number of people suffering from insufficient sleep has increased every year. The gold-standard sleep assessment uses polysomnography (PSG) with various sensors to identify sleep patterns and disorders. However, due to the high cost of PSG and limited availability, many people with sleep disorders are left undiagnosed. Recent wearable sensors and electronics enable portable, continuous monitoring of sleep at home, overcoming the limitations of PSG. This report reviews the advances in wearable sensors, miniaturized electronics, and system packaging for home sleep monitoring. New devices available in the market and systems are collectively summarized based on their overall structure, form factor, materials, and sleep assessment method. It is expected that this review provides a comprehensive view of newly developed technologies and broad insights on wearable sensors and portable electronics toward advanced sleep monitoring as well as at-home sleep assessment.

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Graphical abstract CC BY-NC-ND · PubMed Central
Figure 1 Overview of the existing polysomnography (PSG) setup (left) and recently developed wearable devices (right) for sleep monitoring (A) The conventional PSG setting that requires multiple wired sensors and transducers to measure sleep in a lab. (B) A newly proposed PSG setup with recently developed wearable sensors and electronics systems to measure sleep at home. Low-profile wearable sensors can measure brain activity, heart activity, blood oxygen saturation, respiration, and movement. Brain activity image: reproduced with permission, from ref (Norton et al., 2015), Copyright 2015, National Academy of Sciences. Heart activity image: reproduced with permission, from ref (Kim et al., 2019), Copyright 2019, WILEY-VCH. Pulse wave image: reproduced with permission, from ref (Yokota et al., 2016), Copyright 2016, American Association for the Advancement of Science. Respiration image: reproduced with permission, from ref (Wei et al., 2021), Copyright 2021, American Chemistry Society. Movement image: reproduced with permission, from ref (Kwon et al., 2020), Copyright 2020, Springer Nature.
Figure 1 Overview of the existing polysomnography (PSG) setup (left) and recently developed wearable devices (right) for sleep monitoring (A) The conventional PSG setting that requires multiple wired sensors and transducers to measure sleep in a lab. (B) A newly proposed PSG setup with recently developed wearable sensors and electronics systems to measure sleep at home. Low-profile wearable sensors can measure brain activity, heart activity, blood oxygen saturation, respiration, and movement. Brain activity image: reproduced with permission, from ref (Norton et al., 2015), Copyright 2015, National Academy of Sciences. Heart activity image: reproduced with permission, from ref (Kim et al., 2019), Copyright 2019, WILEY-VCH. Pulse wave image: reproduced with permission, from ref (Yokota et al., 2016), Copyright 2016, American Association for the Advancement of Science. Respiration image: reproduced with permission, from ref (Wei et al., 2021), Copyright 2021, American Chemistry Society. Movement image: reproduced with permission, from ref (Kwon et al., 2020), Copyright 2020, Springer Nature.CC BY-NC-ND · PubMed Central
Figure 2 Examples of brain-signal monitoring wearable devices for sleep analysis (A) Headband-integrated wearable electronics, including dry electrodes, silicone protrusion electrodes, accelerometer, and PPG sensor for measuring EEG, heart rate, and respiration rate during sleep. Confusion matrix showing an accuracy of automated sleep scoring algorithm. Reproduced with permission, from ref (Arnal et al., 2019), Copyright 2019, bioRxiv. (B) In-ear memory foam system with conductive fabric-based EEG electrodes. Plots showing comparable signal quality to scalp EEG and sleep latency detection accuracy. Reproduced with permission, from ref (Alqurashi et al., 2018), Copyright 2018, Dovepress. (C) Adhesive patch-type EEG system that attaches behind the ear. Hypnogram data compare the manually scored sleep stages from PSG and the patch system. Reproduced with permission, from ref (Sterr et al., 2018), Copyright 2018, Frontiers in Human Neuroscience. (D) In-ear-type EEG recording system with integrated dry electrodes. Confusion matrices showing automated scoring results with the proposed system and its agreement with stages from PSG. Reproduced with permission, from ref (Mikkelsen et al., 2019), Copyright 2019, Springer Nature.
Figure 2 Examples of brain-signal monitoring wearable devices for sleep analysis (A) Headband-integrated wearable electronics, including dry electrodes, silicone protrusion electrodes, accelerometer, and PPG sensor for measuring EEG, heart rate, and respiration rate during sleep. Confusion matrix showing an accuracy of automated sleep scoring algorithm. Reproduced with permission, from ref (Arnal et al., 2019), Copyright 2019, bioRxiv. (B) In-ear memory foam system with conductive fabric-based EEG electrodes. Plots showing comparable signal quality to scalp EEG and sleep latency detection accuracy. Reproduced with permission, from ref (Alqurashi et al., 2018), Copyright 2018, Dovepress. (C) Adhesive patch-type EEG system that attaches behind the ear. Hypnogram data compare the manually scored sleep stages from PSG and the patch system. Reproduced with permission, from ref (Sterr et al., 2018), Copyright 2018, Frontiers in Human Neuroscience. (D) In-ear-type EEG recording system with integrated dry electrodes. Confusion matrices showing automated scoring results with the proposed system and its agreement with stages from PSG. Reproduced with permission, from ref (Mikkelsen et al., 2019), Copyright 2019, Springer Nature.CC BY-NC-ND · PubMed Central
Figure 3 Examples of recent wearable heart-activity monitors used for sleep analysis (A) Integrated, portable chest patch device for cardiac function (ECG, ICG, and PCG) monitoring with wet electrodes and a digital stethoscope. Reproduced with permission, from ref (Klum et al., 2020), Copyright 2020, MDPI. (B) A baby pull-up pant, incorporating conductive fabric-based electrodes, accelerometer, and gyroscope to measure ECG and movements. (C) Representative ECG and movement data measured from the wearable device in (B) at awake, REM, and NREM sleep stages. Reproduced with permission, from ref (Ilen et al., 2019), Copyright 2019, Universiteit Gent.
Figure 3 Examples of recent wearable heart-activity monitors used for sleep analysis (A) Integrated, portable chest patch device for cardiac function (ECG, ICG, and PCG) monitoring with wet electrodes and a digital stethoscope. Reproduced with permission, from ref (Klum et al., 2020), Copyright 2020, MDPI. (B) A baby pull-up pant, incorporating conductive fabric-based electrodes, accelerometer, and gyroscope to measure ECG and movements. (C) Representative ECG and movement data measured from the wearable device in (B) at awake, REM, and NREM sleep stages. Reproduced with permission, from ref (Ilen et al., 2019), Copyright 2019, Universiteit Gent.CC BY-NC-ND · PubMed Central
Figure 4 Summary of pulse-wave-based wearable sensors and electronics for sleep monitoring (A) Nose-mountable device with integrated PPG sensor and accelerometer to detect apnea events during sleep while classifying five different sleep positions. (B) Plots showing characteristics of PPG signals during normal breathing and apnea events. (C) Graph (top) and table (bottom) showing sleep position profiles and their signal characteristics, measured by an accelerometer. Reproduced with permission, from ref (Manoni et al., 2020), Copyright 2020, MDPI. (D) In-ear wearable pulse oximeter that measures blood oxygen saturation (SpO2). (E) Plot showing SpO2 data from the in-ear device, compared with a standard finger-worn pulse oximeter. (F) Plot summarizing resting SpO2 data from both devices with multiple subjects to validate the device accuracy. Reproduced with permission, from ref (Davies et al., 2020), Copyright 2020, MDPI.
Figure 4 Summary of pulse-wave-based wearable sensors and electronics for sleep monitoring (A) Nose-mountable device with integrated PPG sensor and accelerometer to detect apnea events during sleep while classifying five different sleep positions. (B) Plots showing characteristics of PPG signals during normal breathing and apnea events. (C) Graph (top) and table (bottom) showing sleep position profiles and their signal characteristics, measured by an accelerometer. Reproduced with permission, from ref (Manoni et al., 2020), Copyright 2020, MDPI. (D) In-ear wearable pulse oximeter that measures blood oxygen saturation (SpO2). (E) Plot showing SpO2 data from the in-ear device, compared with a standard finger-worn pulse oximeter. (F) Plot summarizing resting SpO2 data from both devices with multiple subjects to validate the device accuracy. Reproduced with permission, from ref (Davies et al., 2020), Copyright 2020, MDPI.CC BY-NC-ND · PubMed Central
Figure 5 Summary of wearable sensor systems for monitoring respiration during sleep (A) TENG-based chest belt, made of CNT-doped porous PDMS, to monitor respiration during sleep. (B) Plots showing measured breath and heartbeat signals. Reproduced with permission, from ref (Ding et al., 2018), Copyright 2018, MDPI. (C) Tattoo-like piezoresistive strain sensor, made of a composite of graphene, palladium, and PEDOT:PSS, for enhanced sensitivity and mechanical stability. (D) Finite element analysis results of the strain sensor in (C) under deformation from respiration and heartbeat, showing its mechanical reliability. (E) Two plots showing heartbeat and respiration signals measured by the wearable strain sensor. Reproduced with permission, from ref (Ramírez et al., 2019), Copyright 2019, American Chemical Society.
Figure 5 Summary of wearable sensor systems for monitoring respiration during sleep (A) TENG-based chest belt, made of CNT-doped porous PDMS, to monitor respiration during sleep. (B) Plots showing measured breath and heartbeat signals. Reproduced with permission, from ref (Ding et al., 2018), Copyright 2018, MDPI. (C) Tattoo-like piezoresistive strain sensor, made of a composite of graphene, palladium, and PEDOT:PSS, for enhanced sensitivity and mechanical stability. (D) Finite element analysis results of the strain sensor in (C) under deformation from respiration and heartbeat, showing its mechanical reliability. (E) Two plots showing heartbeat and respiration signals measured by the wearable strain sensor. Reproduced with permission, from ref (Ramírez et al., 2019), Copyright 2019, American Chemical Society.CC BY-NC-ND · PubMed Central
Figure 6 Examples of wearable portable electronics for monitoring body movements (A) Flexible adhesive patch with integrated electrodes to measure leg-EMG during sleep. (B) Comparison of PLMS event detection between the patch in (A) and the conventional PSG for performance validation. Reproduced with permission, from ref (Jortberg et al., 2018), Copyright 2018, Dovepress. (C) Wrist wearable electronics incorporating accelerometer, ambient light sensor, and finger PPG sensor to monitor the user's activity, HR, and strength of ambient light for sleep-wake pattern identification. (D) Plots showing measured activity, ambient light level, and detected sleep interval throughout the seven days of use. Reproduced with permission, from ref (Liao et al., 2020), Copyright 2020, MDPI. (E) Low-power, flexible wearable device with an accelerometer to monitor infants' sleep posture and alert caregivers when a prone position is detected. (F) Schematic diagram showing the workflow of the proposed device from the detection of sleep posture and sending an alert message to the caregivers. Reproduced with permission, from ref (Yun et al., 2020), Copyright 2020, MDPI.
Figure 6 Examples of wearable portable electronics for monitoring body movements (A) Flexible adhesive patch with integrated electrodes to measure leg-EMG during sleep. (B) Comparison of PLMS event detection between the patch in (A) and the conventional PSG for performance validation. Reproduced with permission, from ref (Jortberg et al., 2018), Copyright 2018, Dovepress. (C) Wrist wearable electronics incorporating accelerometer, ambient light sensor, and finger PPG sensor to monitor the user's activity, HR, and strength of ambient light for sleep-wake pattern identification. (D) Plots showing measured activity, ambient light level, and detected sleep interval throughout the seven days of use. Reproduced with permission, from ref (Liao et al., 2020), Copyright 2020, MDPI. (E) Low-power, flexible wearable device with an accelerometer to monitor infants' sleep posture and alert caregivers when a prone position is detected. (F) Schematic diagram showing the workflow of the proposed device from the detection of sleep posture and sending an alert message to the caregivers. Reproduced with permission, from ref (Yun et al., 2020), Copyright 2020, MDPI.CC BY-NC-ND · PubMed Central

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Metadata

Authors
Kwon, S., Kim, H., & Yeo, W.-H.
Affiliations
Georgia Institute of Technology (US)
Corresponding author
Yeo, Woon-Hong
ORCID
Venue
iScience
Publisher
Elsevier BV
Published
2021-05
Volume
24
Issue
5
Pages
102461
ISSN
2589-0042 (ISSN-L)
DOI
10.1016/j.isci.2021.102461
PMC
PMC8113882
OpenAlex
W3156201172
Cited by
209
References
75
Citations by year
2026: 37 · 2025: 45 · 2024: 47 · 2023: 38 · 2022: 34 · 2021: 8
FWCI
2.69
Type
journal article
Language
en
Open access
Licence
Locations
  • iScience (publishedVersion, cc-by-nc-nd)
  • PubMed Central (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
National Institutes of Health
Topics
  • Physical Sciences › Engineering › Biomedical Engineering › Non-Invasive Vital Sign Monitoring
  • Physical Sciences › Engineering › Biomedical Engineering › Advanced Sensor and Energy Harvesting Materials
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Sleep and related disorders
Keywords
wearable sensors, portable electronics, sleep monitoring, home sleep testing, sleep disorders, polysomnography, miniaturized electronics, system packaging

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