Abstract:Wearable sensors that can precisely detect vital signs are highly desirable for monitoring personal health conditions and medical diagnosis. In this paper, we report an ultrasensitive strain sensor consisting of a 150 nm thick highly conductive dimethylsulfoxide-doped poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) sensing layer and an elastic fluorosilicone rubber substrate. This sensor exhibits a high sensitivity at small strains (e.g., gauge factor at 0.6% strain = 280), low limit of detection (<0… Show more
“…S3) leading to switch-like behavior at a certain strain level giving rise to significant resistance change. The microcracking mechanism has been widely applied in the fabrication of ultrasensitive strain sensors 20,27,35,48–50 . However, in these cases the stretching of these structures had to be severely limited, in some cases due to the unstable structure that would lead to irreversible electrical performance such as contact resistance increase or change in the response to an applied strain.Figure 2Optical microscopy images of Ag-DS/CF.…”
Section: Resultsmentioning
confidence: 99%
“…In recent years, several studies have reported highly flexible and stretchable micro- and nanostructured pressure and strain sensors based on polymers embedded with electrically active materials such as silver or gold nanowires (AgNW or AuNW) 6,7,11,12 , carbon nanotubes 9,13–21 (CNT), graphene 22–26 , graphite 24–26 , and other materials including inherently conducting polymers 1,3–5,10,27–34 . Achieving large stretchability (ɛ > 50%) and a high sensitivity (GF > 100) with a wide detection range have been the key factors in the development of strain sensors.…”
Section: Introductionmentioning
confidence: 99%
“…However, several studies have shown that this is possible with highly sensitive piezoresistive structures 11,13,16,20,34,38,39 , but these sensors often show high contact resistance further limiting their feasibility to wearable sensing. Additional functionalities by fabricating transparent 14,16,19,26,27 , self-healing 40 , self-powered 3,41 , tunable 13,17,19,42 , multidimensional 7,12 and multisensing (strain, pressure, temperature, etc.) 3,4,6,10,21,29,32,33,43,44 strain sensors have been investigated.…”
Stretchable and wearable strain sensors have been intensively studied in recent years for applications in human motion monitoring. However, achieving a high-performance strain sensor with high stretchability, ultra-sensitivity, and functionality, such as tunable sensing ranges and sensitivity to various stimuli, has not yet been reported, even though such sensors have great importance for the future applications of wearable electronics. Herein, a novel and versatile strain sensor based on a cracking (silver ink patterned silicone elastomer)-(silver plated nylon structure) (Ag-DS/CF) has been designed and fabricated. The unique structure combined precisely shaped stretchable conductive fabrics and wrinkled Ag-ink pattern to achieve an excellent electrical performance. The Ag-DS/CF could be used to detect both large and subtle human motions and activities, pressure changes, and physical vibrations by achieving high stretchability up to 75%, ultrahigh sensitivity (gauge factor >104–106), tunable sensing ranges (from 7 to 75%). Excellent durability was demonstrated for human motion monitoring with machine washability. The extremely versatile Ag-DS/CF showed outstanding potential for the future of wearable electronics in real-time monitoring of human health, sports performance, etc.
“…S3) leading to switch-like behavior at a certain strain level giving rise to significant resistance change. The microcracking mechanism has been widely applied in the fabrication of ultrasensitive strain sensors 20,27,35,48–50 . However, in these cases the stretching of these structures had to be severely limited, in some cases due to the unstable structure that would lead to irreversible electrical performance such as contact resistance increase or change in the response to an applied strain.Figure 2Optical microscopy images of Ag-DS/CF.…”
Section: Resultsmentioning
confidence: 99%
“…In recent years, several studies have reported highly flexible and stretchable micro- and nanostructured pressure and strain sensors based on polymers embedded with electrically active materials such as silver or gold nanowires (AgNW or AuNW) 6,7,11,12 , carbon nanotubes 9,13–21 (CNT), graphene 22–26 , graphite 24–26 , and other materials including inherently conducting polymers 1,3–5,10,27–34 . Achieving large stretchability (ɛ > 50%) and a high sensitivity (GF > 100) with a wide detection range have been the key factors in the development of strain sensors.…”
Section: Introductionmentioning
confidence: 99%
“…However, several studies have shown that this is possible with highly sensitive piezoresistive structures 11,13,16,20,34,38,39 , but these sensors often show high contact resistance further limiting their feasibility to wearable sensing. Additional functionalities by fabricating transparent 14,16,19,26,27 , self-healing 40 , self-powered 3,41 , tunable 13,17,19,42 , multidimensional 7,12 and multisensing (strain, pressure, temperature, etc.) 3,4,6,10,21,29,32,33,43,44 strain sensors have been investigated.…”
Stretchable and wearable strain sensors have been intensively studied in recent years for applications in human motion monitoring. However, achieving a high-performance strain sensor with high stretchability, ultra-sensitivity, and functionality, such as tunable sensing ranges and sensitivity to various stimuli, has not yet been reported, even though such sensors have great importance for the future applications of wearable electronics. Herein, a novel and versatile strain sensor based on a cracking (silver ink patterned silicone elastomer)-(silver plated nylon structure) (Ag-DS/CF) has been designed and fabricated. The unique structure combined precisely shaped stretchable conductive fabrics and wrinkled Ag-ink pattern to achieve an excellent electrical performance. The Ag-DS/CF could be used to detect both large and subtle human motions and activities, pressure changes, and physical vibrations by achieving high stretchability up to 75%, ultrahigh sensitivity (gauge factor >104–106), tunable sensing ranges (from 7 to 75%). Excellent durability was demonstrated for human motion monitoring with machine washability. The extremely versatile Ag-DS/CF showed outstanding potential for the future of wearable electronics in real-time monitoring of human health, sports performance, etc.
“…Generally, silanization reactions can occur at various substrates containing surface hydroxyl groups, no matter whether they are directly available on the substrates (such as cellulose, metal oxide, SiO 2 , etc.) or obtained via an oxidation reactions, including O 2 plasma, UV/O 3 and Tesla coil treatment . For example, Zhong et al reported a method for patterning of a cellulose paper.…”
Section: Surface Modification Of the Micro‐/nanostructurementioning
confidence: 99%
“…or obtained via an oxidation reactions, including O 2 plasma, UV/O 3 and Tesla coil treatment. [119,120] For example, Zhong et al reported a method for patterning of a cellulose paper. The hydrophobic modification was carried out using the reaction between the OH groups of cellulose and trimethoxyoctadecylsilane (TMOS).…”
Understanding the relationship between liquid manipulation and micro‐/nanostructured interfaces has gained much attention due to the wide potential applications in many fields, such as chemical and biomedical assays, environmental protection, industry, and even daily life. Much work has been done to construct various materials with interfacial liquid manipulation abilities, leading to a range of interesting applications. Herein, different fabrication methods from the top‐down approach to the bottom‐up approach and subsequent surface modifications of micro‐/nanostructured interfaces are first introduced. Then, interactions between the surface and liquid, including liquid wetting, liquid transportation, and a number of corresponding models, together with the definition of hydrophilic/hydrophobic, oleophilic/olephobic, the definition and mechanism of superwetting, including superhydrophobicity, superhydrophilicity, and superoleophobicity, are presented. The micro‐/nanostructured interface, with major applications in self‐cleaning, antifogging, anti‐icing, anticorrosion, drag‐reduction, oil–water separation, water collection, droplet (micro)array, and surface‐directed liquid transport, is summarized, and the mechanisms underlying each application are discussed. Finally, the remaining challenges and future perspectives in this area are included.
Human joints have respective ranges of motion and joint forces corresponding to each kind of joint; this necessitates considerations of the characteristics of human joints to fabricate wearable strain sensors conformable to the human body, and capable of precisely monitoring complex motions of the human body. In the present study, the “all textile‐based highly stretchable structure” that is capable of precisely sensing motions (folding and rotation) of the human joints (finger, wrist, elbow, spine, and knee) is fabricated by optimizing patterns (straight, blind, and zigzag) of conductive yarns employed as the conductive part of the strain sensor, and several textile substrates (braided elastic fabric, knit fabric, and woven fabric), having preferable elasticity and conformability employed for the fabrication of strain sensors suitable for human joints. In particular, the technology, enabling the prestraining of textile substrate, is exploited to fabricate a strain sensor that is capable of outputting selective signals corresponding to the folding motion of the spinal joint over a predetermined angle of motion, and the gait pattern of the wearer of the sensor, attached to his or her knee joint doing folding and rotational motions, is analyzed.
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