Soft electrothermal actuators using silver nanowire heaters

Yao, Shanshan; Cui, Jianxun; Cui, Zheng; Zhu, Yong

doi:10.1039/c6nr09270e

Cited by 155 publications

(144 citation statements)

References 64 publications

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“…For instance, actuators or stimulators may be incorporated to achieve interactive devices that can interact with human body, another device or the environment. [22,37,170,187] Drug-delivery platforms can be integrated to enable therapeutic treatments in response to the information collected by the wearable sensors. [188][189][190] Energy scavengers could negate the need for frequently charging batteries or completely replace the batteries.…”

Section: Integrated Wearable Systemsmentioning

confidence: 99%

Nanomaterial‐Enabled Wearable Sensors for Healthcare

Yao

Swetha

Zhu

2017

Adv Healthcare Materials

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451

296

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humidity level, and concentration of harmful gases, and airborne particulates can provide valuable information for the prediction, management, and treatment of chronic diseases. [4,5] In addition to the applications in wearable health monitoring, continuous tracking of daily and sports activities can offer an efficient way to assess the well-being and athletic performances. [6] In order to ensure a robust and conformal contact with the curvilinear, coarse, and dynamic surface of skin without impeding daily activities, the wearable sensor should have low modulus and high stretchability. The epidermis has a modulus of 140-600 kPa while the dermis has an even lower modulus of 2-80 kPa. [7] Skin itself can be stretched elastically up to 15% and with the help of wrinkles and creases, the overall stretchability can reach as high as 100% during daily motions. [8] In addition to good wearability, wearable sensors should be highly sensitive, lightweight, low-cost, and with low power consumption. To achieve these features, nanomaterials that are compliant, possessing larger surface area and exceptional material properties, and compatible with low-cost fabrication processes are widely employed as building blocks for developing wearable sensors.In this review, we start from a brief overview of nanomaterials, their related structural designs and fabrication processes (Section 2). Following that, recent advances of nanomaterialenabled wearable sensors including temperature, electrophysiological, strain, tactile, electrochemical, and other sensors will be summarized (Section 3). A survey on the integration of multiple sensors and other components into wearable systems will be given in Section 4. The application of nanomaterialenabled wearable sensors for healthcare including health monitoring, activity tracking, and electronic skin will be presented in Section 5. The challenges and opportunities will be discussed at the end. Nanomaterials, Structural Designs, and Fabrication ProcessesNanomaterials can be classified into two categories-top-down fabricated ones and bottom-up synthesized ones. [9] The focus of this review is on the wearable sensors based on bottom-up synthesized nanomaterials. Nanomaterials can be synthesized into various dimensions, from 0D such as metallic nanoparticles (NPs), to 1D such as carbon nanotubes (CNTs), and metallic nanowires (NWs), to 2D such as graphene and transition metal Highly sensitive wearable sensors that can be conformably attached to human skin or integrated with textiles to monitor the physiological parameters of human body or the surrounding environment have garnered tremendous interest. Owing to the large surface area and outstanding material properties, nanomaterials are promising building blocks for wearable sensors. Recent advances in the nanomaterial-enabled wearable sensors including temperature, electrophysiological, strain, tactile, electrochemical, and environmental sensors are presented in this review. Integration of multiple sensors for multimodal sensing and integration with...

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Section: Integrated Wearable Systemsmentioning

confidence: 99%

Nanomaterial‐Enabled Wearable Sensors for Healthcare

Yao

Swetha

Zhu

2017

Adv Healthcare Materials

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451

296

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“…Recently, a promising Ag nanowire (Ag NW)-based ETA with a very low driving voltage (<5 V) has developed. [23] However, the Ag NW embedded multilayers exhibit a weak bonding strength (0.72 N cm −1 ) [33] between actuator multilayers, and can therefore be delaminated during the generation of mechanical stress at the interface. Thus, further development to achieve low driving voltage and robust bonding simultaneously is needed.…”

Section: Wwwadvmattechnoldementioning

confidence: 99%

“…[21,22] Unfortunately, this approach requires the use of highly aligned nanomaterials and complex electrical paths, which limits the material scope and increases the driving voltage. Alternatively, the shape diversity problem has been solved by attachment of stiff materials [23] on some parts or by making use of the anisotropic expansion of an actuation material. [24,25] However, the design diversity needs to be increased further, as expansion directions cannot be locally controlled with a single substrate geometry, and the attachment of stiff materials does not allow for continuous shape actuation.…”

mentioning

confidence: 99%

Heterogeneous Conductance‐Based Locally Shape‐Morphable Soft Electrothermal Actuator

Ahn

Jeong

Zhao

et al. 2019

Adv Materials Technologies

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appropriate for human-machine interactions and use in wearable devices, as they can handle soft materials and arbitrary shapes. [1][2][3] Soft actuators can be driven by mechanical, [4,5] optical, [6][7][8][9] chemical, [10] magnetic, [11][12][13] and electrical [14,15] stimuli but need to be actuated with an easily accessible power source for practical applications. Among them, electrical stimuli provided by electroactive and field-activated polymers such as electro-driven hydrogels [16] and ionic polymer-metal composites (IPMCs) [17] are considered to be the most suited for this purpose. However, electro-driven hydrogels can be used only in electrolyte-containing environments, and IPMCs feature a short-range working stroke. Thus, recent research has focused on electrically stimulated actuators driven by Joule heating rather than by direct electrical stimulation, as exemplified by shape memory polymers (SMPs) [18] and electrothermal actuators (ETAs). [19,20] SMPs exhibit the disadvantages of limited material and actuation shape diversity, as they are driven by two-stage discontinuous deformation of a specific polymer over its transition temperature. Therefore, ETAs, which are driven by bending due to the coefficient of thermal expansion (CTE)

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“…Third, choose proper elastic substrate materials with greater thermal expansion and excellent flexibility such as polyimide (PI), PDMS and so on. Among these polymers, PDMS has been widely used as the substrate in recent years in order to form larger coefficient of thermal expansion difference with the heating layer to increase the deformation further, such as the structure of SACNS/PDMS, sG/PDMS, CNT/PDMS, rGO/PDMS, PI/AgNW/PDMS, CNT(BP)/PDMS, and many others. In addition, studies have shown that decreasing the thickness of the actuator in an appropriate range can help achieving a shorter response time greatly due to the short heat transfer path as well as enlarging the deformation in a degree.…”

Section: Thermoelectric Coupling Devicementioning

confidence: 99%

Graphene‐Based Devices for Thermal Energy Conversion and Utilization

Tian

Sun

et al. 2019

Adv Funct Materials

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Thermal energy conversion and utilization of integrated circuits is a very important research topic. Graphene is a new 2D material with superior electrical, mechanical, thermal, and optical properties, which is expected to continue Moore's law and make breakthroughs in the direction of “More than Moore.” Graphene‐based functionalized devices are applied in various aspects, including breakthroughs in thermal devices, due to their high thermal conductivity and thermal rectification. According to the coupling of different physical quantities, graphene‐based thermal devices can be divided into four categories: uncoupled thermal devices, thermoacoustic coupling devices, thermoelectric coupling devices, and thermo‐optical coupling devices. The structure, working mechanism, and performance of these devices are discussed, as well as the coupling methods of physical quantities. Moreover, scale‐up production of graphene and prospect for future graphene‐based thermal devices are summarized. In‐depth study of the development tendency of these graphene‐based thermal devices is expected to contribute to the development of new high‐performance thermal nanoelectronic devices in the future.

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Soft electrothermal actuators using silver nanowire heaters

Cited by 155 publications

References 64 publications

Nanomaterial‐Enabled Wearable Sensors for Healthcare

Nanomaterial‐Enabled Wearable Sensors for Healthcare

Heterogeneous Conductance‐Based Locally Shape‐Morphable Soft Electrothermal Actuator

Graphene‐Based Devices for Thermal Energy Conversion and Utilization

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