Recently, in healthcare sectors, specifically for personalized health monitoring, motion sensing, and human–machine interactions, the rising demand for stretchable and soft electronic devices is significant. In particular, stretchable, skin mountable, breathable, wearable, light weight, and highly sensitive sensors are needed for detecting subtle deformation arising from human physiological signals and have potential applications in health diagnosis. In this review, we discuss flexible, noninvasive, and wearable sensors based on micro/nanofibers with unique sensing capabilities for detecting human vital signs such as body motion, temperature, heartbeat, respiration rate, and blood glucose level, which have applications in both fitness-monitoring and medical diagnosis. Here, the latest successful examples of micro/nanofiber based flexible and wearable human vital signs monitoring sensors in the form of film, mat, yarn, fabric, textiles, etc., are outlined and discussed in detail. Discussion includes the fiber fabrication technique, sensing mechanism, device structure, sensor performance, and data processing. Some of the latest fabricated self-powered devices with integrated sensing platforms are also reviewed. Finally, this article reveals the existing challenges that are still to be overcome associated with wearable technologies for applications in health monitoring, diagnosis, and rehabilitation.
References
1.
See https://www.mordorintelligence.com/industry-reports/wearable-technology-market for “
Wearable Technology Market: Growth, Trends, and Forecast, 2020–2025
.”2.
H.
Jin
, Y. S.
Abu-Raya
, and H.
Haick
, “Advanced materials for health monitoring with skin-based wearable devices
,” Adv. Healthcare Mater.
6
, 1700024
(2017
).3.
M.
Stoppa
and A.
Chiolerio
, “Wearable electronics and smart textiles: A critical review
,” Sensors
14
, 11957
–11992
(2014
).4.
S.
Yao
, P.
Swetha
, and Y.
Zhu
, “Nanomaterial-enabled wearable sensors for healthcare
,” Adv. Healthcare Mater.
7
, 1700889
(2018
).5.
W.
Zeng
et al, “Fiber-based wearable electronics: A review of materials, fabrication, devices, and applications
,” Adv. Mater.
26
, 5310
–5336
(2014
).6.
J. V.
Hoof
, G.
Demiris
, and E. J. M.
Wouters
, Handbook of Smart Homes, Health Care and Well-Being
(Springer
, Basel, Switzerland
, 2017
).7.
S.
Majumder
et al, “Smart homes for elderly healthcare—Recent advances and research challenges
,” Sensors
17
, 2496
(2017
).8.
World Health Organization (WHO)
, see https://www.who.int/world-health-day/2012/toolkit/background/en/ for “Are you ready? What you need to know about ageing
.”9.
C. D.
Mathers
and D.
Loncar
, “Projections of global mortality and burden of disease from 2002 to 2030
,” PLoS Med.
3
, e442
(2006
).10.
X.
Wang
, Z.
Liu
, and T.
Zhang
, “Flexible sensing electronics for wearable/attachable health monitoring
,” Small
13
, 1602790
(2017
).11.
M.
Ha
, S.
Lim
, and H.
Ko
, “Wearable and flexible sensors for user-interactive health-monitoring devices
,” J. Mater. Chem. B
6
, 4043
–4064
(2018
).12.
L.
Wang
, Z.
Lou
, K.
Jiang
, and G.
Shen
, “Bio-multifunctional smart wearable sensors for medical devices
,” Adv. Intell. Syst.
1
, 1900040
(2019
).13.
K.
Qi
et al, “A highly stretchable nanofiber-based electronic skin with pressure-, strain-, and flexion-sensitive properties for health and motion monitoring
,” ACS Appl. Mater. Interfaces
9
, 42951
–42960
(2017
).14.
S.
Wu
et al, “Novel electrically conductive porous PDMS/carbon nanofiber composites for deformable strain sensors and conductors
,” ACS Appl. Mater. Interfaces
9
, 14207
–14215
(2017
).15.
J. J.
Park
, W. J.
Hyun
, S. C.
Mun
, Y. T.
Park
, and O. O.
Park
, “Highly stretchable and wearable graphene strain sensors with controllable sensitivity for human motion monitoring
,” ACS Appl. Mater. Interfaces
7
, 6317
–6324
(2015
).16.
S. Y.
Hong
et al, “Stretchable active matrix temperature sensor array of polyaniline nanofibers for electronic skin
,” Adv. Mater.
28
, 930
–935
(2016
).17.
W.
He
et al, “Integrated textile sensor patch for real-time and multiplex sweat analysis
,” Sci. Adv.
5
, eaax0649
(2019
).18.
J.
Park
et al, “Soft, smart contact lenses with integrations of wireless circuits, glucose sensors, and displays
,” Sci. Adv.
4
, eaap9841
(2018
).19.
T.
Xu
et al, “Electrospun CuO-nanoparticles-modified polycaprolactone @ polypyrrole fibers: An application to sensing glucose in saliva
,” Nanomaterials
8
, 133
(2018
).20.
C.
Deng
, J.
Zhang
, X.
Yu
, W.
Zhang
, and X.
Zhang
, “Determination of acetone in human breath by gas chromatography–mass spectrometry and solid-phase microextraction with on-fiber derivatization
,” J. Chromatogr. B
810
, 269
–275
(2004
).21.
M.
Jian
et al, “Advanced carbon materials for flexible and wearable sensors
,” Sci. China Mater.
60
, 1026
–1062
(2017
).22.
W. A. D. M.
Jayathilaka
et al, “Significance of nanomaterials in wearables: A review on wearable actuators and sensors
,” Adv. Mater.
31
, 1805921
(2019
).23.
M.
Amjadi
, K.-U.
Kyung
, I.
Park
, and M.
Sitti
, “Stretchable, skin-mountable, and wearable strain sensors and their potential applications: A review
,” Adv. Funct. Mater.
26
, 1678
–1698
(2016
).24.
D.-H.
Kim
et al, “Epidermal electronics
,” Science
333
, 838
–843
(2011
).25.
R. C.
Webb
et al, “Ultrathin conformal devices for precise and continuous thermal characterization of human skin
,” Nat. Mater.
12
, 938
–944
(2013
).26.
J.
Yang
et al, “Wearable temperature sensor based on graphene nanowalls
,” RSC Adv.
5
, 25609
–25615
(2015
).27.
H.
Jin
, T.-P.
Huynh
, and H.
Haick
, “Self-healable sensors based nanoparticles for detecting physiological markers via skin and breath: Toward disease prevention via wearable devices
,” Nano Lett.
16
, 4194
–4202
(2016
).28.
S.
Gong
et al, “A wearable and highly sensitive pressure sensor with ultrathin gold nanowires
,” Nat. Commun.
5
, 3132
(2014
).29.
S.-J.
Park
, J.
Kim
, M.
Chu
, and M.
Khine
, “Highly flexible wrinkled carbon nanotube thin film strain sensor to monitor human movement
,” Adv. Mater. Technol.
1
, 1600053
(2016
).30.
J.
Jeon
, H.-B.-R.
Lee
, and Z.
Bao
, “Flexible wireless temperature sensors based on Ni microparticle-filled binary polymer composites
,” Adv. Mater.
25
, 850
–855
(2013
).31.
J.
Zhou
, X.
Xu
, H.
Yu
, and G.
Lubineau
, “Deformable and wearable carbon nanotube microwire-based sensors for ultrasensitive monitoring of strain, pressure and torsion
,” Nanoscale
9
, 604
–612
(2017
).32.
S.
Yan
et al, “An ultra-sensitive, rapidly responsive strain sensor based on silver microflakes by simple process
,” ChemistrySelect
4
, 4407
–4415
(2019
).33.
M.
Zhang
et al, “A hybrid fibers based wearable fabric piezoelectric nanogenerator for energy harvesting application
,” Nano Energy
13
, 298
–305
(2015
).34.
L.
Guan
et al, “Stretchable-fiber-confined wetting conductive liquids as wearable human health monitors
,” Adv. Funct. Mater.
26
, 4511
–4517
(2016
).35.
A.
Zucchelli
, M. L.
Focarete
, C.
Gualandi
, and S.
Ramakrishna
, “Electrospun nanofibers for enhancing structural performance of composite materials
,” Polym. Adv. Technol.
22
, 339
–349
(2011
).36.
Y.
Zhang
, “Electrospun nanofibers with tunable electrical conductivity
,” Ph.D. thesis (Massachusetts Institute of Technology
, 2013
).37.
A.
Chinnappan
, C.
Baskar
, S.
Baskar
, G.
Ratheesh
, and S.
Ramakrishna
, “An overview of electrospun nanofibers and their application in energy storage, sensors and wearable/flexible electronics
,” J. Mater. Chem. C
5
, 12657
–12673
(2017
).38.
N.
Hedin
, V.
Sobolev
, L.
Zhang
, Z.
Zhu
, and H.
Fong
, “Electrical properties of electrospun carbon nanofibers
,” J. Mater. Sci.
46
, 6453
–6456
(2011
).39.
S.
Ramakrishna
et al, “Electrospun nanofibers: Solving global issues
,” Mater. Today
9
, 40
–50
(2006
).40.
W. E.
Teo
and S.
Ramakrishna
, “A review on electrospinning design and nanofibre assemblies
,” Nanotechnology
17
, R89
–R106
(2006
).41.
T. Q.
Trung
and N.-E.
Lee
, “Flexible and stretchable physical sensor integrated platforms for wearable human-activity monitoring and personal healthcare
,” Adv. Mater.
28
, 4338
–4372
(2016
).42.
K.
Maity
and D.
Mandal
, “All-organic high-performance piezoelectric nanogenerator with multilayer assembled electrospun nanofiber mats for self-powered multifunctional sensors
,” ACS Appl. Mater. Interfaces
10
, 18257
–18269
(2018
).43.
G.
Zhao
et al, “Piezoelectric polyacrylonitrile nanofiber film-based dual-function self-powered flexible sensor
,” ACS Appl. Mater. Interfaces
10
, 15855
–15863
(2018
).44.
K.
Dong
et al, “A highly stretchable and washable all-yarn-based self-charging knitting power textile composed of fiber triboelectric nanogenerators and supercapacitors
,” ACS Nano
11
, 9490
–9499
(2017
).45.
S.
Jung
, J.
Lee
, T.
Hyeon
, M.
Lee
, and D.-H.
Kim
, “Fabric-based integrated energy devices for wearable activity monitors
,” Adv. Mater.
26
, 6329
–6334
(2014
).46.
S. H.
Ji
, Y. S.
Cho
, and J. S.
Yun
, “Wearable core-shell piezoelectric nanofiber yarns for body movement energy harvesting
,” Nanomaterials
9
, 555
–559
(2019
).47.
S. H.
Ji
, W.
Lee
, and J. S.
Yun
, “All-in-one piezo-triboelectric energy harvester module based on piezoceramic nanofibers for wearable devices
,” ACS Appl. Mater. Interfaces
12
, 18609
–18616
(2020
).48.
X.
Chen
, S.
Xu
, N.
Yao
, and Y.
Shi
, “1.6 V nanogenerator for mechanical energy harvesting using PZT nanofibers
,” Nano Lett.
10
, 2133
–2137
(2010
).49.
X.
Zhang
, L.
Ji
, O.
Toprakci
, Y.
Liang
, and M.
Alcoutlabi
, “Electrospun nanofiber-based anodes, cathodes, and separators for advanced lithium-ion batteries
,” Polym. Rev.
51
, 239
–264
(2011
).50.
K.
Bachtin
et al, “Activation and degradation of electrospun LiFePO4 battery cathodes
,” J. Power Sources
396
, 386
–394
(2018
).51.
S.-H.
Wang
, P.-L.
Kuo
, C.-T.
Hsieh
, and H.
Teng
, “Design of poly(acrylonitrile)-based gel electrolytes for high-performance lithium ion batteries
,” ACS Appl. Mater. Interfaces
6
, 19360
–19370
(2014
).52.
X.
Liu
et al, “Electrospun PU@GO separators for advanced lithium ion batteries
,” J. Membr. Sci.
555
, 1
–6
(2018
).53.
S.
Santangelo
, “Electrospun nanomaterials for energy applications: Recent advances
,” Appl. Sci.
9
, 1049
(2019
).54.
J.
Liang
et al, “MoS2-based all-purpose fibrous electrode and self-powering energy fiber for efficient energy harvesting and storage
,” Adv. Energy Mater.
7
, 1601208
(2017
).55.
Y.
Zhang
, M.
Xie
, V.
Adamaki
, H.
Khanbareh
, and C. R.
Bowen
, “Control of electro-chemical processes using energy harvesting materials and devices
,” Chem. Soc. Rev.
46
, 7757
–7786
(2017
).56.
J.
Xue
, T.
Wu
, Y.
Dai
, and Y.
Xia
, “Electrospinning and electrospun nanofibers: Methods, materials, and applications
,” Chem. Rev.
119
, 5298
–5415
(2019
).57.
N.
Ashammakhi
et al, “Minimally invasive and regenerative therapeutics
,” Adv. Mater.
31
, 1804041
(2019
).58.
R.
Ravichandran
et al, “Minimally invasive injectable short nanofibers of poly(glycerol sebacate) for cardiac tissue engineering
,” Nanotechnology
23
, 385102
(2012
).59.
Y.
Khan
, A. E.
Ostfeld
, C. M.
Lochner
, A.
Pierre
, and A. C.
Arias
, “Monitoring of vital signs with flexible and wearable medical devices
,” Adv. Mater.
28
, 4373
–4395
(2016
).60.
S.
Choi
, H.
Lee
, R.
Ghaffari
, T.
Hyeon
, and D. H.
Kim
, “Recent advances in flexible and stretchable bio-electronic devices integrated with nanomaterials
,” Adv. Mater.
28
, 4203
–4218
(2016
).61.
A.
Eatemadi
, H.
Daraee
, N.
Zarghami
, H.
Melat Yar
, and A.
Akbarzadeh
, “Nanofiber: Synthesis and biomedical applications
,” Artif. Cells Nanomed., Biotechnol.
44
, 111
–121
(2016
).62.
S.-H.
Park
, H. B.
Lee
, S. M.
Yeon
, J.
Park
, and N. K.
Lee
, “Flexible and stretchable piezoelectric sensor with thickness-tunable configuration of electrospun nanofiber mat and elastomeric substrates
,” ACS Appl. Mater. Interfaces
8
, 24773
–24781
(2016
).63.
S. J.
Kim
et al, “High durability and waterproofing rGO/SWCNT-fabric-based multifunctional sensors for human-motion detection
,” ACS Appl. Mater. Interfaces
10
, 3921
–3928
(2018
).64.
Z.
Wei
, M.
Wan
, T.
Lin
, and L.
Dai
, “Polyaniline nanotubes doped with sulfonated carbon nanotubes made via a self-assembly process
,” Adv. Mater.
15
, 136
–139
(2003
).65.
J.
Wang
et al, “Self-assembled peptide nanofibers on graphene oxide as a novel nanohybrid for biomimetic mineralization of hydroxyapatite
,” Carbon
89
, 20
–30
(2015
).66.
Z.
Wang
, S.
Wu
, J.
Wang
, A.
Yu
, and G.
Wei
, “Carbon nanofiber-based functional nanomaterials for sensor applications
,” Nanomaterials
9
, 1045
(2019
).67.
J.
He
et al, “Continuous twisted nanofiber yarns fabricated by double conjugate electrospinning
,” Fibers Polym.
14
, 1857
–1863
(2013
).68.
A.
Ghorbani-Choghamarani
and Z.
Taherinia
, “Synthesis of peptide nanofibers decorated with palladium nanoparticles and its application as an efficient catalyst for the synthesis of sulfides via reaction of aryl halides with thiourea or 2-mercaptobenzothiazole
,” RSC Adv.
6
, 59410
–59421
(2016
).69.
Z.
Ma
, M.
Kotaki
, R.
Inai
, and S.
Ramakrishna
, “Potential of nanofiber matrix as tissue-engineering scaffolds
,” Tissue Eng.
11
, 101
–109
(2005
).70.
I.
Alghoraibi
and S.
Alomari
, “Different methods for nanofiber design and fabrication
,” Handbook of Nanofibers
(Springer International Publishing
, 2019
), pp. 79
–124
.71.
S. K.
Ghosh
et al, “Electrospun gelatin nanofiber based self-powered bio-e-skin for health care monitoring
,” Nano Energy
36
, 166
–175
(2017
).72.
H.
Wu
et al, “Electrospun metal nanofiber webs as high-performance transparent electrode
,” Nano Lett.
10
, 4242
–4248
(2010
).73.
Z. H.
Liu
, C. T.
Pan
, L. W.
Lin
, and H. W.
Lai
, “Piezoelectric properties of PVDF/MWCNT nanofiber using near-field electrospinning
,” Sens. Actuators, A
193
, 13
–24
(2013
).74.
A.
Aziz
et al, “Core–shell electrospun polycrystalline ZnO nanofibers for ultra-sensitive NO2 gas sensing
,” ACS Appl. Mater. Interfaces
10
, 43817
–43823
(2018
).75.
J.
Yoon
, H.-S.
Yang
, B.-S.
Lee
, and W.-R.
Yu
, “Recent progress in coaxial electrospinning: New parameters, various structures, and wide applications
,” Adv. Mater.
30
, 1704765
(2018
).76.
A.
Khalf
, K.
Singarapu
, and S. V.
Madihally
, “Cellulose acetate core–shell structured electrospun fiber: Fabrication and characterization
,” Cellulose
22
, 1389
–1400
(2015
).77.
M.-F.
Lin
, J.
Xiong
, J.
Wang
, K.
Parida
, and P. S.
Lee
, “Core-shell nanofiber mats for tactile pressure sensor and nanogenerator applications
,” Nano Energy
44
, 248
–255
(2018
).78.
N. G.
Rim
, C. S.
Shin
, and H.
Shin
, “Current approaches to electrospun nanofibers for tissue engineering
,” Biomed. Mater.
8
, 014102
(2013
).79.
S. K.
Tiwari
and S. S.
Venkatraman
, “Importance of viscosity parameters in electrospinning: Of monolithic and core–shell fibers
,” Mater. Sci. Eng. C
32
, 1037
–1042
(2012
).80.
D.
Sun
, C.
Chang
, S.
Li
, and L.
Lin
, “Near-field electrospinning
,” Nano Lett.
6
, 839
–842
(2006
).81.
Y. K.
Fuh
, B. S.
Wang
, and C.-Y.
Tsai
, “Self-powered pressure sensor with fully encapsulated 3D printed wavy substrate and highly-aligned piezoelectric fibers array
,” Sci. Rep.
7
, 6759
(2017
).82.
X.
Shi
et al, “Electrospinning of nanofibers and their applications for energy devices
,” J. Nanomater.
2015
, 1
–20
.83.
A. R.
Nagle
et al, “A direct 3D suspension near-field electrospinning technique for the fabrication of polymer nanoarrays
,” Nanotechnology
30
, 195301
(2019
).84.
Y.
Zhou
et al, “Carbon nanofiber yarns fabricated from co-electrospun nanofibers
,” Mater. Des.
95
, 591
–598
(2016
).85.
J.-X.
He
, K.
Qi
, Y.-M.
Zhou
, and S.-Z.
Cui
, “Fabrication of continuous nanofiber yarn using novel multi-nozzle bubble electrospinning
,” Polym. Int.
63
, 1288
–1294
(2014
).86.
S.
Chawla
, M.
Naraghi
, and A.
Davoudi
, “Effect of twist and porosity on the electrical conductivity of carbon nanofiber yarns
,” Nanotechnology
24
, 255708
(2013
).87.
W.
Li
et al, “A self-template strategy for the synthesis of mesoporous carbon nanofibers as advanced supercapacitor electrodes
,” Adv. Energy Mater.
1
, 382
–386
(2011
).88.
C.
Yan
, G.
Chen
, X.
Zhou
, J.
Sun
, and C.
Lv
, “Template-based engineering of carbon-doped Co3O4 hollow nanofibers as anode materials for lithium-ion batteries
,” Adv. Funct. Mater.
26
, 1428
–1436
(2016
).89.
H.-W.
Liang
et al, “Macroscopic-scale template synthesis of robust carbonaceous nanofiber hydrogels and aerogels and their applications
,” Angew. Chem., Int. Ed.
51
, 5101
–5105
(2012
).90.
G.
Che
, B. B.
Lakshmi
, C. R.
Martin
, E. R.
Fisher
, and R. S.
Ruoff
, “Chemical vapor deposition based synthesis of carbon nanotubes and nanofibers using a template method
,” Chem. Mater.
10
, 260
–267
(1998
).91.
W.
Zhang
et al, “Supramolecular self-assembly bioinspired synthesis of luminescent gold nanocluster-embedded peptide nanofibers for temperature sensing and cellular imaging
,” Bioconjugate Chem.
28
, 2224
–2229
(2017
).92.
C.
Li
et al, “Amyloid-hydroxyapatite bone biomimetic composites
,” Adv. Mater.
26
, 3207
–3212
(2014
).93.
S. C. B.
Mannsfeld
et al, “Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers
,” Nat. Mater.
9
, 859
–864
(2010
).94.
W.
Zhong
et al, “A nanofiber based artificial electronic skin with high pressure sensitivity and 3D conformability
,” Nanoscale
8
, 12105
–12112
(2016
).95.
J.
Park
et al, “Tactile-direction-sensitive and stretchable electronic skins based on human-skin-inspired interlocked microstructures
,” ACS Nano
8
, 12020
–12029
(2014
).96.
J.
Park
et al, “Giant tunneling piezoresistance of composite elastomers with interlocked microdome arrays for ultrasensitive and multimodal electronic skins
,” ACS Nano
8
, 4689
–4697
(2014
).97.
M.
Ha
et al, “Bioinspired interlocked and hierarchical design of ZnO nanowire arrays for static and dynamic pressure-sensitive electronic skins
,” Adv. Funct. Mater.
25
, 2841
–2849
(2015
).98.
M.-J.
Yin
, Z.
Yin
, Y.
Zhang
, Q.
Zheng
, and A. P.
Zhang
, “Micropatterned elastic ionic polyacrylamide hydrogel for low-voltage capacitive and organic thin-film transistor pressure sensors
,” Nano Energy
58
, 96
–104
(2019
).99.
H.-J.
Kim
et al, “Silk nanofiber-networked bio-triboelectric generator: Silk bio-TEG
,” Adv. Energy Mater.
6
, 1502329
(2016
).100.
R. S.
Timsit
, “Electrical contact resistance: Properties of stationary interfaces
,” IEEE Trans. Compon. Package Technol.
22
, 85
–98
(1999
).101.
N.
Liu
et al, “Electrospun PEDOT:PSS-PVA nanofiber based ultrahigh-strain sensors with controllable electrical conductivity
,” J. Mater. Chem.
21
, 18962
–18966
(2011
).102.
X.
Xiao
et al, “High-strain sensors based on ZnO nanowire/polystyrene hybridized flexible films
,” Adv. Mater.
23
, 5440
–5444
(2011
).103.
C. L.
Choong
et al, “Highly stretchable resistive pressure sensors using a conductive elastomeric composite on a micropyramid array
,” Adv. Mater.
26
, 3451
–3458
(2014
).104.
J.
Cai
, S.
Chawla
, and M.
Naraghi
, “Piezoresistive effect of individual electrospun carbon nanofibers for strain sensing
,” Carbon
77
, 738
–746
(2014
).105.
S.
Beeby
, G.
Ensell
, M.
Kraft
, and N.
White
, MEMS Mechanical Sensors
(Cambridge University Press
, 2004
).106.
X.
Li
et al, “Ultracomfortable hierarchical nanonetwork for highly sensitive pressure sensor
,” ACS Nano
14
, 9605
(2020
).107.
X.
Liao
et al, “Flexible and highly sensitive strain sensors fabricated by pencil drawn for wearable monitor
,” Adv. Funct. Mater.
25
, 2395
–2401
(2015
).108.
Q.
Wang
, M.
Jian
, C.
Wang
, and Y.
Zhang
, “Carbonized silk nanofiber membrane for transparent and sensitive electronic skin
,” Adv. Funct. Mater.
27
, 1605657
(2017
).109.
H. A. K.
Toprakci
, S. K.
Kalanadhabhatla
, R. J.
Spontak
, and T. K.
Ghosh
, “Polymer nanocomposites containing carbon nanofibers as soft printable sensors exhibiting strain-reversible piezoresistivity
,” Adv. Funct. Mater.
23
, 5536
–5542
(2013
).110.
O. Y.
Kweon
, S. J.
Lee
, and J. H.
Oh
, “Wearable high-performance pressure sensors based on three-dimensional electrospun conductive nanofibers
,” NPG Asia Mater.
10
, 540
–551
(2018
).111.
H.
Park
et al, “Stretchable array of highly sensitive pressure sensors consisting of polyaniline nanofibers and Au-coated polydimethylsiloxane micropillars
,” ACS Nano
9
, 9974
–9985
(2015
).112.
Y.
Zhou
et al, “Highly sensitive, self-powered and wearable electronic skin based on pressure-sensitive nanofiber woven fabric sensor
,” Sci. Rep.
7
, 12949
(2017
).113.
H.
Ren
et al, “Transfer-medium-free nanofiber-reinforced graphene film and applications in wearable transparent pressure sensors
,” ACS Nano
13
, 5541
–5548
(2019
).114.
A.
Chiolerio
et al, “Inkjet-printed PEDOT:PSS electrodes on plasma-modified PDMS nanocomposites: Quantifying plasma treatment hardness
,” RSC Adv.
4
, 51477
–51485
(2014
).115.
W.
Zhong
et al, “Ultrasensitive wearable pressure sensors assembled by surface-patterned polyolefin elastomer nanofiber membrane interpenetrated with silver nanowires
,” ACS Appl. Mater. Interfaces
10
, 42706
–42714
(2018
).116.
Y.
Cheng
, R.
Wang
, J.
Sun
, and L.
Gao
, “A stretchable and highly sensitive graphene-based fiber for sensing tensile strain, bending, and torsion
,” Adv. Mater.
27
, 7365
–7371
(2015
).117.
Q.
Zheng
, B.
Shi
, Z.
Li
, and Z. L.
Wang
, “Recent progress on piezoelectric and triboelectric energy harvesters in biomedical systems
,” Adv. Sci.
4
, 1700029
(2017
).118.
K.
Roy
et al, “A self-powered wearable pressure sensor and pyroelectric breathing sensor based on GO interfaced PVDF nanofibers
,” ACS Appl. Nano Mater.
2
, 2013
–2025
(2019
).119.
Y.
Kuang
and M.
Zhu
, “Evaluation and validation of equivalent properties of macro fibre composites for piezoelectric transducer modelling
,” Compos. Part B: Eng.
158
, 189
–197
(2019
).120.
X.
Lu
, H.
Qu
, and M.
Skorobogatiy
, “Piezoelectric microstructured fibers via drawing of multimaterial preforms
,” Sci. Rep.
7
, 2907
(2017
).121.
X.
Wang
et al, “Recent progress in electronic skin
,” Adv. Sci.
2
, 1500169
(2015
).122.
A.
Chiolerio
et al, “Effect of the fabrication method on the functional properties of BaTiO3: PVDF nanocomposites
,” J. Mater. Sci.
48
, 6943
–6951
(2013
).123.
M.
Laurenti
et al, “Lead-free piezoelectrics: V3+ to V5+ ion conversion promoting the performances of V-doped zinc oxide
,” Sci. Rep.
7
, 41957
(2017
).124.
M. M.
Alam
, A.
Sultana
, and D.
Mandal
, “Biomechanical and acoustic energy harvesting from TiO2 nanoparticle modulated PVDF nanofiber made high performance nanogenerator
,” ACS Appl. Energy Mater.
1
, 3103
–3112
(2018
).125.
W.
Deng
et al, “Cowpea-structured PVDF/ZnO nanofibers based flexible self-powered piezoelectric bending motion sensor towards remote control of gestures
,” Nano Energy
55
, 516
–525
(2019
).126.
Z.
Li
and Z. L.
Wang
, “Air/liquid-pressure and heartbeat-driven flexible fiber nanogenerators as a micro/nano-power source or diagnostic sensor
,” Adv. Mater.
23
, 84
–89
(2011
).127.
Y. K.
Fuh
and B. S.
Wang
, “Near field sequentially electrospun three-dimensional piezoelectric fibers arrays for self-powered sensors of human gesture recognition
,” Nano Energy
30
, 677
–683
(2016
).128.
Y.-K.
Fuh
, P.-C.
Chen
, Z.-M.
Huang
, and H.-C.
Ho
, “Self-powered sensing elements based on direct-write, highly flexible piezoelectric polymeric nano/microfibers
,” Nano Energy
11
, 671
–677
(2015
).129.
T.
Huang
et al, “Phase-separation-induced PVDF/graphene coating on fabrics toward flexible piezoelectric sensors
,” ACS Appl. Mater. Interfaces
10
, 30732
–30740
(2018
).130.
A.
Damilano
et al, “A robust capacitive digital read-out circuit for a scalable tactile skin
,” IEEE Sens. J.
17
, 2682
–2695
(2017
).131.
W.
Yang
et al, “A breathable and screen-printed pressure sensor based on nanofiber membranes for electronic skins
,” Adv. Mater. Technol.
3
, 1700241
(2018
).132.
P.
Cataldi
et al, “Carbon nanofiber versus graphene-based stretchable capacitive touch sensors for artificial electronic skin
,” Adv. Sci.
5
, 1700587
(2018
).133.
Y.
Ai
et al, “All rGO-on-PVDF-nanofibers based self-powered electronic skins
,” Nano Energy
35
, 121
–127
(2017
).134.
J.
Wang
, R.
Suzuki
, M.
Shao
, F.
Gillot
, and S.
Shiratori
, “Capacitive pressure sensor with wide-range, bendable, and high sensitivity based on the bionic komochi konbu structure and Cu/Ni nanofiber network
,” ACS Appl. Mater. Interfaces
11
, 11928
–11935
(2019
).135.
Z.
Wang
et al, “Flexible and washable poly(ionic liquid) nanofibrous membrane with moisture proof pressure sensing for real-life wearable electronics
,” ACS Appl. Mater. Interfaces
11
, 27200
–27209
(2019
).136.
X.
You
et al, “Stretchable capacitive fabric electronic skin woven by electrospun nanofiber coated yarns for detecting tactile and multimodal mechanical stimuli
,” J. Mater. Chem. C
6
, 12981
–12991
(2018
).137.
G.
Zhu
et al, “Triboelectric-generator-driven pulse electrodeposition for micropatterning
,” Nano Lett.
12
, 4960
–4965
(2012
).138.
F.-R.
Fan
et al, “Transparent triboelectric nanogenerators and self-powered pressure sensors based on micropatterned plastic films
,” Nano Lett.
12
, 3109
–3114
(2012
).139.
H.-Y.
Mi
et al, “High-performance flexible triboelectric nanogenerator based on porous aerogels and electrospun nanofibers for energy harvesting and sensitive self-powered sensing
,” Nano Energy
48
, 327
–336
(2018
).140.
S.
Zhao
et al, “All-nanofiber-based ultralight stretchable triboelectric nanogenerator for self-powered wearable electronics
,” ACS Appl. Energy Mater.
1
, 2326
–2332
(2018
).141.
R.
Cao
et al, “Self-powered nanofiber-based screen-print triboelectric sensors for respiratory monitoring
,” Nano Res.
11
, 3771
–3779
(2018
).142.
B.
Zhang
et al, “Self-powered acceleration sensor based on liquid metal triboelectric nanogenerator for vibration monitoring
,” ACS Nano
11
, 7440
–7446
(2017
).143.
X.
Wang
et al, “A highly stretchable transparent self-powered triboelectric tactile sensor with metallized nanofibers for wearable electronics
,” Adv. Mater.
30
, 1706738
(2018
).144.
X.
Li
et al, “3D fiber-based hybrid nanogenerator for energy harvesting and as a self-powered pressure sensor
,” ACS Nano
8
, 10674
–10681
(2014
).145.
X.
Wang
et al, “A flexible triboelectric-piezoelectric hybrid nanogenerator based on P(VDF-TrFE) nanofibers and PDMS/MWCNT for wearable devices
,” Sci. Rep.
6
, 36409
(2016
).146.
X.
Chen
et al, “Flexible fiber-based hybrid nanogenerator for biomechanical energy harvesting and physiological monitoring
,” Nano Energy
38
, 43
–50
(2017
).147.
W.
Seung
et al, “Nanopatterned textile-based wearable triboelectric nanogenerator
,” ACS Nano
9
, 3501
–3509
(2015
).148.
K. N.
Kim
et al, “Highly stretchable 2D fabrics for wearable triboelectric nanogenerator under harsh environments
,” ACS Nano
9
, 6394
–6400
(2015
).149.
Y.-C.
Lai
et al, “Single-thread-based wearable and highly stretchable triboelectric nanogenerators and their applications in cloth-based self-powered human-interactive and biomedical sensing
,” Adv. Funct. Mater.
27
, 1604462
(2017
).150.
Y.
Wang
et al, “Flexible electrically resistive-type strain sensors based on reduced graphene oxide-decorated electrospun polymer fibrous mats for human motion monitoring
,” Carbon
126
, 360
–371
(2018
).151.
X.
Liao
et al, “A highly stretchable ZnO@fiber-based multifunctional nanosensor for strain/temperature/UV detection
,” Adv. Funct. Mater.
26
, 3074
–3081
(2016
).152.
A.
Ostadfar
, Biofluid Mechanics: Principles and Applications
(Elsevier/Academic Press
, 2016
), pp. 113
–116
.153.
A.
Taebi
, B.
Solar
, A.
Bomar
, R.
Sandler
, and H.
Mansy
, “Recent advances in seismocardiography
,” Vibration
2
, 64
–86
(2019
).154.
S.
Rolfe
, “The importance of respiratory rate monitoring
,” Br. J. Nurs.
28
, 504
–508
(2019
).155.
E.
Getnet Tsega
, V. K.
Katiyar
, and P.
Gupta
, “Breathing patterns of healthy human response to different levels of physical activity
,” J. Biomed. Eng. Technol.
7
, 1
–4
(2019
).156.
M.
Seiffert
, F.
Holstein
, R.
Schlosser
, and J.
Schiller
, “Next generation cooperative wearables: generalized activity assessment computed fully distributed within a wireless body area network
,” IEEE Access
5
, 16793
–16807
(2017
).157.
N.
Gueugneau
, T.
Pozzo
, C.
Darlot
, and C.
Papaxanthis
, “Daily modulation of the speed–accuracy trade-off
,” Neuroscience
356
, 142
–150
(2017
).158.
J.
Suckale
and M.
Solimena
, “Pancreas islets in metabolic signaling-focus on the beta-cell
,” Front. Biosci.
13
, 7156
(2008
).159.
M.
Alsahli
and J. E.
Gerich
, “Glucose physiology, normal
,” Encyclopedia of Endocrine Diseases
(Elsevier
, 2014
), Vol. 2
, pp. 72
–86
.160.
H. C.
Koydemir
and A.
Ozcan
, “Wearable and implantable sensors for biomedical applications
,” Annu. Rev. Anal. Chem.
11
, 127
–146
(2018
).161.
Y.
Gao
, L.
Zhang
, M.
Du
, and M. I.
Vai
, “Design of human motion detection based on the human body communication
,” in TENCON 2015-2015 IEEE Region 10 Conference
(IEEE
, 2015
), pp. 1
–4
.162.
P. L.
Sheridan
, J.
Solomont
, N.
Kowall
, and J. M.
Hausdorff
, “Influence of executive function on locomotor function: Divided attention increases gait variability in Alzheimer's disease
,” J. Am. Geriatr. Soc.
51
, 1633
–1637
(2003
).163.
P. R.
Cavanagh
, B. A.
Lipsky
, A. W.
Bradbury
, and G.
Botek
, “Treatment for diabetic foot ulcers
,” Lancet
366
, 1725
–1735
(2005
).164.
N.
Nazmi
, M.
Azizi
, A.
Rahman
, S.
Yamamoto
, and S.
Anom
, “Walking gait event detection based on electromyography signals using artificial neural network
,” Biomed. Signal Process. Control
47
, 334
–343
(2019
).165.
R. G.
Scalisi
et al, “Inkjet printed flexible electrodes for surface electromyography
,” Org. Electron.
18
, 89
–94
(2015
).166.
S.
Ryu
et al, “Extremely elastic wearable carbon nanotube fiber strain sensor for monitoring of human motion
,” ACS Nano
9
, 5929
–5936
(2015
).167.
H. H.
Shi
, N.
Khalili
, T.
Morrison
, and H. E.
Naguib
, “Self-assembled nanorod structures on nanofibers for textile electrochemical capacitor electrodes with intrinsic tactile sensing capabilities
,” ACS Appl. Mater. Interfaces
10
, 19037
–19046
(2018
).168.
J.
Lee
et al, “Conductive fiber-based ultrasensitive textile pressure sensor for wearable electronics
,” Adv. Mater.
27
, 2433
–2439
(2015
).169.
Y.
Ding
, J.
Yang
, C. R.
Tolle
, and Z.
Zhu
, “A highly stretchable strain sensor based on electrospun carbon nanofibers for human motion monitoring
,” RSC Adv.
6
, 79114
–79120
(2016
).170.
Y.
Lu
, M. C.
Biswas
, Z.
Guo
, J.-W.
Jeon
, and E. K.
Wujcik
, “Recent developments in bio-monitoring via advanced polymer nanocomposite-based wearable strain sensors
,” Biosens. Bioelectron.
123
, 167
–177
(2019
).171.
F.
Ramsteiner
and T.
Armbrust
, “Fatigue crack growth in polymers
,” Polym. Test.
20
, 321
–327
(2001
).172.
A. K.
Yetisen
, J. L.
Martinez-Hurtado
, B.
Ünal
, A.
Khademhosseini
, and H.
Butt
, “Wearables in medicine
,” Adv. Mater.
30
, 1706910
(2018
).173.
A. J.
Bandodkar
, W.
Jia
, and J.
Wang
, “Tattoo-based wearable electrochemical devices: A review
,” Electroanalysis
27
, 562
–572
(2015
).174.
A. J.
Bandodkar
and J.
Wang
, “Non-invasive wearable electrochemical sensors: A review
,” Trends Biotechnol.
32
, 363
–371
(2014
).175.
S.
Zhao
et al, “Recent advancements in flexible and stretchable electrodes for electromechanical sensors: Strategies, materials, and features
,” ACS Appl. Mater. Interfaces
9
, 12147
–12164
(2017
).176.
Kenry
, J. C.
Yeo
, and C. T.
Lim
, “Emerging flexible and wearable physical sensing platforms for healthcare and biomedical applications
,” Microsyst. Nanoeng.
2
, 16043
(2016
).177.
W. B.
White
et al, “Average daily blood pressure, not office blood pressure, is associated with progression of cerebrovascular disease and cognitive decline in older people
,” Circulation
124
, 2312
–2319
(2011
).178.
J. N.
Cohn
et al, “Noninvasive pulse wave analysis for the early detection of vascular disease
,” Hypertension
26
, 503
–508
(1995
).179.
J. B.
Borges
et al, “Reversibility of lung collapse and hypoxemia in early acute respiratory distress syndrome
,” Am. J. Respir. Crit. Care Med.
174
, 268
–278
(2006
).180.
D. E.
O'Donnell
, “Hyperinflation, dyspnea, and exercise intolerance in chronic obstructive pulmonary disease
,” Proc. Am. Thorac. Soc.
3
, 180
–184
(2006
).181.
L.-G.
Larsson
, A.
Lindberg
, K. A.
Franklin
, and B.
Lundback
, “Symptoms related to obstructive sleep apnoea are common in subjects with asthma, chronic bronchitis and rhinitis in a general population
,” Respir. Med.
95
, 423
–429
(2001
).182.
K.
Malinauskas
, P.
Palevicius
, M.
Ragulskis
, V.
Ostasevicius
, and R.
Dauksevicius
, “Validation of noninvasive MOEMS-assisted measurement system based on CCD sensor for radial pulse analysis
,” Sensors
13
, 5368
–5380
(2013
).183.
K.
Mohri
, T.
Kondo
, H.
Sugino
, J.
Yamasaki
, and K.
Yoshino
, “Non-contact linear displacement sensors using amorphous-core multivibrators for mechanocardiography
,” IEEE Trans. Magn.
21
, 2071
–2073
(1985
).184.
A.
Tricoli
, N.
Nasiri
, and S.
De
, “Wearable and miniaturized sensor technologies for personalized and preventive medicine
,” Adv. Funct. Mater.
27
, 1605271
(2017
).185.
K.
Takei
, W.
Honda
, S.
Harada
, T.
Arie
, and S.
Akita
, “Toward flexible and wearable human-interactive health-monitoring devices
,” Adv. Healthcare Mater.
4
, 487
–500
(2015
).186.
S. S.
Evans
, E. A.
Repasky
, and D. T.
Fisher
, “Fever and the thermal regulation of immunity: The immune system feels the heat
,” Nat. Rev. Immunol.
15
, 335
–349
(2015
).187.
C. L.
Lim
, C.
Byrne
, and J. K. W.
Lee
, “Human thermoregulation and measurement of body temperature in exercise and clinical settings
,” Ann. Acad. Med. Singapore
37
, 347
–353
(2008
).188.
H.
Barcroft
and O. G.
Edholm
, “The effect of temperature on blood flow and deep temperature in the human forearm
,” J. Physiol.
102
, 5
–20
(1943
).189.
C.
Wang
, K.
Xia
, M.
Zhang
, M.
Jian
, and Y.
Zhang
, “An all-silk-derived dual-mode e-skin for simultaneous temperature–pressure detection
,” ACS Appl. Mater. Interfaces
9
, 39484
–39492
(2017
).190.
M.-H.
You
et al, “A self-powered flexible hybrid piezoelectric–pyroelectric nanogenerator based on non-woven nanofiber membranes
,” J. Mater. Chem. A
6
, 3500
–3509
(2018
).191.
H. S.
Jo
et al, “Wearable transparent thermal sensors and heaters based on metal-plated fibers and nanowires
,” Nanoscale
10
, 19825
–19834
(2018
).192.
Y.
Yang
and W.
Gao
, “Wearable and flexible electronics for continuous molecular monitoring
,” Chem. Soc. Rev.
48
, 1465
–1491
(2019
).193.
H.
Jiyong
, Z.
Yinda
, Z.
Hele
, G.
Yuanyuan
, and Y.
Xudong
, “Mixed effect of main electrospinning parameters on the β-phase crystallinity of electrospun PVDF nanofibers
,” Smart Mater. Struct.
26
, 085019
(2017
).194.
J.
Zhong
et al, “Fiber-based generator for wearable electronics and mobile medication
,” ACS Nano
8
, 6273
–6280
(2014
).195.
See https://apps.who.int/iris/bitstream/handle/10665/204871/9789241565257_eng.pdf;jsessionid=B40BB7F3A78C73FF8CE3E84E6817F112?sequence=1 for “
WHO Global Report,
Global Report on Diabetes, World Health Organization, 2016
.”196.
Z.
Jiang
et al, “Highly sensitive acetone sensor based on Eu-doped SnO2 electrospun nanofibers
,” Ceram. Int.
42
, 15881
–15888
(2016
).197.
S.-J.
Choi
et al, “Selective detection of acetone and hydrogen sulfide for the diagnosis of diabetes and halitosis using SnO2 nanofibers functionalized with reduced graphene oxide nanosheets
,” ACS Appl. Mater. Interfaces
6
, 2588
–2597
(2014
).198.
W.
Liu
et al, “A highly sensitive and moisture-resistant gas sensor for diabetes diagnosis with Pt@In2O3 nanowires and a molecular sieve for protection
,” NPG Asia Mater.
10
, 293
–308
(2018
).199.
L.
Wang
, A.
Teleki
, S. E.
Pratsinis
, and P. I.
Gouma
, “Ferroelectric WO3 nanoparticles for acetone selective detection
,” Chem. Mater.
20
, 4794
–4796
(2008
).200.
A. M.
Diskin
, P.
Španěl
, and D.
Smith
, “Time variation of ammonia, acetone, isoprene and ethanol in breath: A quantitative SIFT-MS study over 30 days
,” Physiol. Meas.
24
, 107
–119
(2003
).201.
Y. M.
Sabri
et al, “Soot template TiO2 fractals as a photoactive gas sensor for acetone detection
,” Sens. Actuators, B
275
, 215
–222
(2018
).202.
S.
Malik
, R.
Khadgawat
, S.
Anand
, and S.
Gupta
, “Non-invasive detection of fasting blood glucose level via electrochemical measurement of saliva
,” Springerplus
5
, 701
(2016
).203.
V. E.
Coyle
et al, “Co3O4 needles on Au honeycomb as a non-invasive electrochemical biosensor for glucose in saliva
,” Biosens. Bioelectron.
141
, 111479
(2019
).204.
Y.
Du
, W.
Zhang
, and M.
Wang
, “Sensing of salivary glucose using nano-structured biosensors
,” Biosensors
6
, 10
(2016
).205.
A.
Soni
and S. K.
Jha
, “A paper strip based non-invasive glucose biosensor for salivary analysis
,” Biosens. Bioelectron.
67
, 763
–768
(2015
).206.
M. X.
Chu
et al, “Soft contact lens biosensor for in situ monitoring of tear glucose as non-invasive blood sugar assessment
,” Talanta
83
, 960
–965
(2011
).207.
D. K.
Sen
and G. S.
Sarin
, “Tear glucose levels in normal people and in diabetic patients
,” Br. J. Ophthalmol.
64
, 693
–695
(1980
).208.
J. D.
Lane
, D. M.
Krumholz
, R. A.
Sack
, and C.
Morris
, “Tear glucose dynamics in diabetes mellitus
,” Curr. Eye Res.
31
, 895
–901
(2006
).209.
G.-Z.
Chen
, I.-S.
Chan
, and D. C. C.
Lam
, “Capacitive contact lens sensor for continuous non-invasive intraocular pressure monitoring
,” Sens. Actuators, A
203
, 112
–118
(2013
).210.
Y.-T.
Liao
, H.
Yao
, A.
Lingley
, B.
Parviz
, and B. P.
Otis
, “A 3-μW CMOS glucose sensor for wireless contact-lens tear glucose monitoring
,” IEEE J. Solid-State Circuits
47
, 335
–344
(2012
).211.
J.
Kim
et al, “Wearable smart sensor systems integrated on soft contact lenses for wireless ocular diagnostics
,” Nat. Commun.
8
, 14997
(2017
).212.
Z.
Sonner
et al, “The microfluidics of the eccrine sweat gland, including biomarker partitioning, transport, and biosensing implications
,” Biomicrofluidics
9
, 031301
(2015
).213.
J.
Moyer
, D.
Wilson
, I.
Finkelshtein
, B.
Wong
, and R.
Potts
, “Correlation between sweat glucose and blood glucose in subjects with diabetes
,” Diabetes Technol. Ther.
14
, 398
–402
(2012
).214.
A.
Mena-Bravo
and M. D.
Luque de Castro
, “Sweat: A sample with limited present applications and promising future in metabolomics
,” J. Pharm. Biomed. Anal.
90
, 139
–147
(2014
).215.
Y.
Chen
et al, “Skin-like biosensor system via electrochemical channels for noninvasive blood glucose monitoring
,” Sci. Adv.
3
, e1701629
(2017
).216.
Y.-L.
Liu
et al, “A stretchable electrochemical sensor for inducing and monitoring cell mechanotransduction in real time
,” Angew. Chem., Int. Ed.
56
, 9454
–9458
(2017
).217.
J.
Kim
, R.
Kumar
, A. J.
Bandodkar
, and J.
Wang
, “Advanced materials for printed wearable electrochemical devices: A review
,” Adv. Electron. Mater.
3
, 1600260
(2017
).218.
Z.-H.
Jin
et al, “Conductive polymer-coated carbon nanotubes to construct stretchable and transparent electrochemical sensors
,” Anal. Chem.
89
, 2032
–2038
(2017
).219.
K. J.
Kubota
, J. A.
Chen
, and M. A.
Little
, “Machine learning for large-scale wearable sensor data in Parkinson's disease: Concepts, promises, pitfalls, and futures
,” Mov. Disord.
31
, 1314
–1326
(2016
).220.
K.
Rajan
, E.
Garofalo
, and A.
Chiolerio
, “Wearable intrinsically soft, stretchable, flexible devices for memories and computing
,” Sensors
18
, 367
–316
(2018
).221.
L.
Persano
et al, “High performance piezoelectric devices based on aligned arrays of nanofibers of poly(vinylidenefluoride-co-trifluoroethylene)
,” Nat. Commun.
4
, 1633
(2013
).222.
T.
Yilmaz
, R.
Foster
, and Y.
Hao
, “Detecting vital signs with wearable wireless sensors
,” Sensors
10
, 10837
–10862
(2010
).223.
L.
Zhang
, Y.
Tang
, and L.
Tong
, “Micro-/nanofiber optics: Merging photonics and material science on nanoscale for advanced sensing technology
,” iScience
23
, 100810
(2020
).224.
L.
Zhang
et al, “Ultrasensitive skin-like wearable optical sensors based on glass micro/nanofibers
,” Opto-Electron. Adv.
3
, 19002201
–19002207
(2020
).225.
J.
Li
, J.
Chen
, and F.
Xu
, “Sensitive and wearable optical microfiber sensor for human health monitoring
,” Adv. Mater. Technol.
3
, 1800296
(2018
).226.
A.
Nag
, S. C.
Mukhopadhyay
, and J.
Kosel
, “Wearable flexible sensors: A review
,” IEEE Sens. J.
17
, 3949
–3960
(2017
).227.
A.
Zanella
, N.
Bui
, A.
Castellani
, L.
Vangelista
, and M.
Zorzi
, “Internet of things for smart cities
,” IEEE Internet Things J.
1
, 22
–32
(2014
).228.
J.
Lee
, H.-A.
Kao
, and S.
Yang
, “Service innovation and smart analytics for industry 4.0 and big data environment
,” Procedia CIRP
16
, 3
–8
(2014
).229.
K.
Suzuki
et al, “Rapid-response, widely stretchable sensor of aligned MWCNT/elastomer composites for human motion detection
,” ACS Sens.
1
, 817
–825
(2016
).230.
M.
Zhang
, C.
Wang
, Q.
Wang
, M.
Jian
, and Y.
Zhang
, “Sheath–core graphite/silk fiber made by dry-meyer-rod-coating for wearable strain sensors
,” ACS Appl. Mater. Interfaces
8
, 20894
–20899
(2016
).231.
M.
Lee
et al, “A hybrid piezoelectric structure for wearable nanogenerators
,” Adv. Mater.
24
, 1759
–1764
(2012
).232.
H. J.
Sim
et al, “Stretchable triboelectric fiber for self-powered kinematic sensing textile
,” Sci. Rep.
6
, 35153
(2016
).© 2020 Author(s).
2020
Author(s)
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