One-pot preparation of porous piezoresistive sensor with high strain sensitivity via emulsion-templated polymerization

Yang, Liting; Wang, Ruiying; Song, Qingting; Yu, Liu; Zhao, Qiangqiang; Shen, Yifeng

doi:10.1016/j.compositesa.2017.06.017

Cited by 32 publications

(23 citation statements)

References 21 publications

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“…This difference is ascribed to the peculiar shape of the S unit cell, which leads to 3D structures with bigger trabeculae, which under deformation give rise to the building up of more effective conductive pathways. To the best of our knowledge, such high values have never been reported for graphene-based polymer porous structures when subjected to compressive strain [47]. It has to be pointed out that GF values are even higher for deformation extents lower than 8%, and then tend to plateau as the maximum strain value is approached (Figure 8).…”

Section: Mechanical and Piezoresistive Characterizationmentioning

confidence: 74%

Selective Laser Sintering Fabricated Thermoplastic Polyurethane/Graphene Cellular Structures with Tailorable Properties and High Strain Sensitivity

et al. 2019

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Electrically conductive and flexible thermoplastic polyurethane/graphene (TPU/GE) porous structures were successfully fabricated by selective laser sintering (SLS) technique starting from graphene (GE)-wrapped thermoplastic polyurethane (TPU) powders. Several 3D mathematically defined architectures, with porosities from 20% to 80%, were designed by using triply periodic minimal surfaces (TMPS) equations corresponding to Schwarz (S), Diamond (D), and Gyroid (G) unit cells. The resulting three-dimensional porous structures exhibit an effective conductive network due to the segregation of graphene nanoplatelets previously assembled onto the TPU powder surface. GE nanoplatelets improve the thermal stability of the TPU matrix, also increasing its glass transition temperature. Moreover, the porous structures realized by S geometry display higher elastic modulus values in comparison to D and G-based structures. Upon cyclic compression tests, all porous structures exhibit a robust negative piezoresistive behavior, regardless of their porosity and geometry, with outstanding strain sensitivity. Gauge factor (GF) values of 12.4 at 8% strain are achieved for S structures at 40 and 60% porosity, and GF values up to 60 are obtained for deformation extents lower than 5%. Thermal conductivity of the TPU/GE structures significantly decreases with increasing porosity, while the effect of the structure architecture is less relevant. The TPU/GE porous structures herein reported hold great potential as flexible, highly sensitive, and stable strain sensors in wearable or implantable devices, as well as dielectric elastomer actuators.

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Section: Mechanical and Piezoresistive Characterizationmentioning

confidence: 74%

Selective Laser Sintering Fabricated Thermoplastic Polyurethane/Graphene Cellular Structures with Tailorable Properties and High Strain Sensitivity

et al. 2019

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“…One way to address this challenge is to either fabricate a 3D template structure and subsequently etch away the template [ 126 ] or to cure the active material around a material that can be subsequently etched away. [ 127,128 ] Kim et al developed a new process to create porous structures for resistive pressure sensors (Figure 11C,D). [ 87 ] As previously discussed, they developed DMESA, which involves surfactant‐stabilized aqueous droplets in the oil solution to fabricate porous active layers with uniformly sized spherical micropores, providing a more controllable technique for creating porous active layers (Figures 4I and 6A).…”

Section: Resistive Pressure Sensorsmentioning

confidence: 99%

Microengineering Pressure Sensor Active Layers for Improved Performance

Ruth

Feig

Tran

et al. 2020

Adv Funct Materials

383

277

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Pressure sensors play an integral role in a wide range of applications, such as soft robotics and health monitoring. In order to meet this demand, many groups microengineer the active layer-the layer that deforms under pressure and dictates changes in the output signal-of capacitive, resistive/piezoresistive, piezoelectric, and triboelectric pressure sensors in order to improve sensor performance. Geometric microengineering of the active layer has been shown to improve performance parameters such as sensitivity, dynamic range, limit of detection, and response and relaxation times. There are a wide range of implemented designs, including microdomes, micropyramids, lines or microridges, papillae, microspheres, micropores, and microcylinders, each offering different advantages for a particular application. It is important to compare the techniques by which the microengineered active layers are designed and fabricated as they may provide additional insights on compatibility and sensing range limits. To evaluate each fabrication method, it is critical to take into account the active layer uniformity, ease of fabrication, shape and size versatility and tunability, and scalability of both the device and the fabrication process. By better understanding how microengineering techniques and design compares, pressure sensors can be targetedly designed and implemented.

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“…Because these diameters are approximately one order of magnitude smaller than any previously reported value for solid-templated composite foams, 8,11,29,38,54 it was expected that the material would exhibit enhanced pressure sensitivity. 54,55 Both the wrinkled pore wall in Figure 1f and the TEM image in Figure 1g indicate the presence of the rGO particles at the pore walls. Additionally, as the SEM images in Figure S2a−c show, the addition of GO very strongly affected the pore size distribution.…”

Section: ■ Results and Discussionmentioning

confidence: 95%

Development of a Highly Sensitive, Broad-Range Hierarchically Structured Reduced Graphene Oxide/PolyHIPE Foam for Pressure Sensing

Yang

Liu

Filipe

et al. 2019

ACS Appl. Mater. Interfaces

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Highly sensitive pressure sensors are usually made from soft materials that allow large deformations to be obtained when very small pressures are applied. Unfortunately, this current paradigm limits the ability to create sensors capable of high sensitivities and broad dynamic ranges as these materials are prone to saturation responses when attempting to obtain measurements involving high pressures. In this paper, we detail a piezoresistive pressure sensor that is capable of high sensitivity over a pressure range spanning from 0.6 Pa (a mosquito touching a surface) to 200 kPa (an elephant standing on the surface). The sensor's ability to cover such a broad dynamic range is made possible by the fairly hard foam used in its construction as this material is capable of propagating strain in a highly effective manner due to its hierarchical porous structure. The material was fabricated by using high-internal-phase emulsion (HIPE) as a template to generate a highly porous material consisting of small pores packed between larger ones whose inner walls are lined with reduced graphene oxide. The developed foam exhibits very fast response times (less than 15.4 ms) and excellent cyclic stability (at least 10,000 cycles). Furthermore, it is capable of responding to the entire tactile pressure range, and it can be formatted as pixelated arrays, which makes it highly suitable for integration into wearable electronic devices. Such arrays were built and used to identify and render the shape of objects with different geometries, including a sphere, a triangle, a square, and two nearly identical rods differing only by 0.4 mm in diameter.

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One-pot preparation of porous piezoresistive sensor with high strain sensitivity via emulsion-templated polymerization

Cited by 32 publications

References 21 publications

Selective Laser Sintering Fabricated Thermoplastic Polyurethane/Graphene Cellular Structures with Tailorable Properties and High Strain Sensitivity

Selective Laser Sintering Fabricated Thermoplastic Polyurethane/Graphene Cellular Structures with Tailorable Properties and High Strain Sensitivity

Microengineering Pressure Sensor Active Layers for Improved Performance

Development of a Highly Sensitive, Broad-Range Hierarchically Structured Reduced Graphene Oxide/PolyHIPE Foam for Pressure Sensing

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