Recent Progress in Electronic Skin

Wang, Xiandi; Dong, Lin; Zhang, Hanlu; Yu, Ruomeng; Pan, Caofeng; Wang, Zhong Lin

doi:10.1002/advs.201500169

Cited by 855 publications

(557 citation statements)

References 214 publications

(224 reference statements)

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“…A wide range of different material platforms including carbon-based nanostructures123 or organic compounds456, metals78 and oxides9 are currently investigated to realize devices that would be key to several emerging applications often related to the interface between humans and communication and information technology. Examples are wearable electronic transducers and processors or electronic energy harvesting systems as employed in electronic skin1011121314, implantable bioelectronic devices151617 or electronic textiles7. Progress in flexible electronics relies on the development of electronic materials and devices resistant to mechanical deformation.…”

mentioning

confidence: 99%

Direct imaging of defect formation in strained organic flexible electronics by Scanning Kelvin Probe Microscopy

Cramer

Travaglini

Lai

et al. 2016

Sci Rep

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The development of new materials and devices for flexible electronics depends crucially on the understanding of how strain affects electronic material properties at the nano-scale. Scanning Kelvin-Probe Microscopy (SKPM) is a unique technique for nanoelectronic investigations as it combines non-invasive measurement of surface topography and surface electrical potential. Here we show that SKPM in non-contact mode is feasible on deformed flexible samples and allows to identify strain induced electronic defects. As an example we apply the technique to investigate the strain response of organic thin film transistors containing TIPS-pentacene patterned on polymer foils. Controlled surface strain is induced in the semiconducting layer by bending the transistor substrate. The amount of local strain is quantified by a mathematical model describing the bending mechanics. We find that the step-wise reduction of device performance at critical bending radii is caused by the formation of nano-cracks in the microcrystal morphology of the TIPS-pentacene film. The cracks are easily identified due to the abrupt variation in SKPM surface potential caused by a local increase in resistance. Importantly, the strong surface adhesion of microcrystals to the elastic dielectric allows to maintain a conductive path also after fracture thus providing the opportunity to attenuate strain effects.

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mentioning

confidence: 99%

Direct imaging of defect formation in strained organic flexible electronics by Scanning Kelvin Probe Microscopy

Cramer

Travaglini

Lai

et al. 2016

Sci Rep

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“…To fulfill these demands, a broad range of materials, fabrication processes, and structural designs of the tactile sensor have been developed, [8] while sensing principles are mainly classified as either resistive [9][10][11] or capacitive types. [12][13][14] Many of resistive sensors use nanomaterial-embedded composites and exploit changes in contact resistance between the nanomaterials in the composite matrix (such as elastomer) under pressure loading, showing improved pressure sensitivity and mechanical flexibility compared to silicon-or metal-based piezoresistive sensors.…”

mentioning

confidence: 99%

Flexible, Transparent, Sensitive, and Crosstalk‐Free Capacitive Tactile Sensor Array Based on Graphene Electrodes and Air Dielectric

Pyo

Choi

Kim

2017

Adv Elect Materials

118

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optical transparency, and mechanical flexibility of the sensor are considered as essential requirements for use in future tactile sensing applications. To fulfill these demands, a broad range of materials, fabrication processes, and structural designs of the tactile sensor have been developed, [8] while sensing principles are mainly classified as either resistive [9][10][11] or capacitive types. [12][13][14] Many of resistive sensors use nanomaterial-embedded composites and exploit changes in contact resistance between the nanomaterials in the composite matrix (such as elastomer) under pressure loading, showing improved pressure sensitivity and mechanical flexibility compared to silicon-or metal-based piezoresistive sensors. [15] However, resistive tactile sensors suffer from signal drift due to temperature changes and require high power consumption. In addition, complicated circuit arrangement for multipoint recognition is regarded as a drawback to be addressed. [7,16] Compared to resistive tactile sensing mechanisms, capacitive tactile sensors have advantages in terms of temperature independence, low power consumption, stability against long-term signal drift, and easy multipoint recognition by simple assembly of row and column electrodes. [16,17] In general, the structure of a capacitive sensor consists of two parallel electrodes with a dielectric layer between them. Highly compressible dielectric materials are essential to achieve high sensitivity; a lower Young's modulus of the dielectric leads to greater deformation when pressure is applied to the sensor, resulting in a larger change in capacitance. Accordingly, considerable efforts have been devoted to using elastomers with low Young's modulus as dielectric materials, including polydimethylsiloxane (PDMS), [18] polyurethane, [19] or Ecoflex. [12] However, these low-modulus elastomers also tend to have high viscoelasticity, slowing their response and relaxation times. [20] To overcome this limitation and further improve the sensitivity, a few tactile sensors make use of the strategy of structuring the dielectric layer by fabricating a microstructured surface in an orderly fashion. [7,20,21] The microstructured dielectric layer led to much higher sensitivity and faster response/relaxation time by allowing a larger deformation compared to conventional capacitive sensors with a plain dielectric layer under equal applied pressure. Nevertheless, The development of sensitive, flexible, and transparent tactile sensors is of great interest for next-generation flexible displays and human-machine interfaces. Although a few materials and structural designs have been previously developed for high-performance tactile sensors, achieving flexibility, full transparency, and highly sensitive multipoint recognition without crosstalk remains a significant challenge for such systems. This work demonstrates a capacitive tactile sensor composed of two sets of facing graphene electrodes separated by spacers, which forms an air dielectric between them. The air gap facilitates mor...

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“…Among these approaches, vibration energy harvesters (VEHs) receive majority of research interests and have been demonstrated by using one of piezoelectric39404142, electrostatic43444546, electromagnetic474849505152 and triboelectric5354555657 mechanisms. In addition to self-powered piezoelectric sensors, there are some self-powered triboelectric sensors reported to detect force, pressure, tactile, displacement, vibration, liquid volume, liquid flow, ion concentration, and organic concentration, etc585960616263646566676869. General speaking, when two triboelectrically opposite materials come in contact, they generate equal and opposite charges according to their place in the triboelectric series.…”

mentioning

confidence: 99%

Broadband Energy Harvester Using Non-linear Polymer Spring and Electromagnetic/Triboelectric Hybrid Mechanism

Gupta

Shi

Dhakar

et al. 2017

Sci Rep

104

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Over the years, several approaches have been devised to widen the operating bandwidth, but most of them can only be triggered at high accelerations. In this work, we investigate a broadband energy harvester based on combination of non-linear stiffening effect and multimodal energy harvesting to obtain high bandwidth over wide range of accelerations (0.1 g–2.0 g). In order to achieve broadband behavior, a polymer based spring exhibiting multimodal energy harvesting is used. Besides, non-linear stiffening effect is introduced by using mechanical stoppers. At low accelerations (<0.5 g), the nearby mode frequencies of polymer spring contribute to broadening characteristics, while proof mass engages with mechanical stoppers to introduce broadening by non-linear stiffening at higher accelerations. The electromagnetic mechanism is employed in this design to enhance its output at low accelerations when triboelectric output is negligible. Our device displays bandwidth of 40 Hz even at low acceleration of 0.1 g and it is increased up to 68 Hz at 2 g. When non-linear stiffening is used along with multimodal energy-harvesting, the obtained bandwidth increases from 23 Hz to 68 Hz with percentage increment of 295% at 1.8 g. Further, we have demonstrated the triboelectric output measured as acceleration sensing signals in terms of voltage and current sensitivity of 4.7 Vg−1 and 19.7 nAg−1, respectively.

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Recent Progress in Electronic Skin

Cited by 855 publications

References 214 publications

Direct imaging of defect formation in strained organic flexible electronics by Scanning Kelvin Probe Microscopy

Direct imaging of defect formation in strained organic flexible electronics by Scanning Kelvin Probe Microscopy

Flexible, Transparent, Sensitive, and Crosstalk‐Free Capacitive Tactile Sensor Array Based on Graphene Electrodes and Air Dielectric

Broadband Energy Harvester Using Non-linear Polymer Spring and Electromagnetic/Triboelectric Hybrid Mechanism

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