Fabrication of hierarchically porous structured PDMS composites and their application as a flexible capacitive pressure sensor

Hwang, Juwon; Kim, Yeongjun; Yang, Hyeondong; Oh, Je Hoon

doi:10.1016/j.compositesb.2021.108607

Cited by 253 publications

(148 citation statements)

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“…Flexible pressure sensors have received tremendous attention due to their potential in monitoring human health [ 1 , 2 , 3 ], human–machine interaction systems [ 4 , 5 ], and intelligent robotics [ 6 , 7 , 8 ]. Thus far, numerous strategies have been proposed to develop pressure sensors with excellent sensing performance based on various sensing mechanisms, including piezoresistive [ 9 , 10 ], capacitive [ 11 , 12 , 13 , 14 ], piezoelectric [ 15 , 16 ], and triboelectric effects [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

“…Microstructured patterns, such as convex [ 21 ], pyramids [ 22 ], pillars [ 23 ], and waves [ 24 ], have been proved to be effective in yielding ultrahigh sensitivity. However, the working range is typically limited to <10 kPa because the patterns quickly collapse even when subjected to low pressure, thereby making the strategy less desirable for most application settings [ 1 ]. In addition, this method requires time-consuming, expensive, and complicated process steps to fabricate the microstructure silicone mold.…”

Section: Introductionmentioning

confidence: 99%

“…Another approach that focuses on the formation of porous structures inside the dielectric layer has been proposed as an alternative to the microstructuring of elastomers, including various fabrication techniques such as the particle–template method [ 1 , 11 , 25 , 26 ], chemical foaming method [ 27 ], and emulsion–template method [ 28 ]. Among these, the particle–template method has emerged as a promising strategy with great potential for providing higher deformability to resulting sensors, along with ease of fabrication at low cost.…”

Section: Introductionmentioning

confidence: 99%

“…Among these, the particle–template method has emerged as a promising strategy with great potential for providing higher deformability to resulting sensors, along with ease of fabrication at low cost. In this strategy, easily dissolvable particles (sugar or NaCl) are added to uncured silicone rubber, such as polydimethylsiloxane (PDMS) [ 1 , 11 ] or Ecoflex [ 25 , 26 ]. After the silicone elastomers are cured, the residual particles are dissolved and removed to obtain a porous dielectric layer.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, in order to monitor human motions, a pressure sensor needs to be sensitive over a working range up to 100 kPa [ 26 ] to cover the overall tactile pressures. It has been frequently reported that pressure sensors fabricated by the particle–template strategy can work at the low-pressure (0−10 kPa) [ 25 ] and medium-pressure regimes (10−100 kPa) [ 11 , 12 ] and broader ranges (130 kPa [ 26 ], 400 kPa [ 1 ]).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Carbonized Cotton Fabric-Based Flexible Capacitive Pressure Sensor Using a Porous Dielectric Layer with Tilted Air Gaps

Kim

2021

Sensors

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Flexible and wearable pressure sensors have attracted significant attention owing to their roles in healthcare monitoring and human–machine interfaces. In this study, we introduce a wide-range, highly sensitive, stable, reversible, and biocompatible pressure sensor based on a porous Ecoflex with tilted air-gap-structured and carbonized cotton fabric (CCF) electrodes. The knitted structure of electrodes demonstrated the effectiveness of the proposed sensor in enhancing the pressure-sensing performance in comparison to a woven structure due to the inherent properties of naturally generated space. In addition, the presence of tilted air gaps in the porous elastomer provided high deformability, thereby significantly improving the sensor sensitivity compared to other dielectric structures that have no or vertical air gaps. The combination of knitted CCF electrodes and the porous dielectric with tilted air gaps achieved a sensitivity of 24.5 × 10−3 kPa−1 at 100 kPa, along with a wide detection range (1 MPa). It is also noteworthy that this novel method is low-cost, facile, scalable, and ecofriendly. Finally, the proposed sensor integrated into a smart glove detected human motions of grasping water cups, thus demonstrating its potential applications in wearable electronics.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Carbonized Cotton Fabric-Based Flexible Capacitive Pressure Sensor Using a Porous Dielectric Layer with Tilted Air Gaps

Kim

2021

Sensors

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Additive Manufacturing of Flexible Strain Sensors Based on Smart Composites for Structural Health Monitoring with High Accuracy and Fidelity

Ahmed,

Bodaghi,

Nauman

et al. 2023

Adv Eng Mater

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This research introduces novel flexible spherical carbon nanoparticle‐based polyurethane conductive ink, which is employed to 3D print strain sensors by a lab‐developed Direct Ink Writing system. Rheological tests are performed, and sensors are pasted on Glass‐Fiber‐Reinforced Plastic specimens to study strain gauge behaviors under quasi‐static loading. The gauge factor in tensile loading is found to be layer width dependent as decreasing the strain gauge’s layer width increases the sensitivity of the strain sensor. A maximum gauge factor of 34 is achieved using a layer width of 0.2mm, 17 times greater than commercially available metal foil strain gauges. The four‐point bend tests are performed under tension/compression to assess the sensor’s strain‐sensing and damage‐monitoring ability. Fractographic analysis is coupled with strain monitoring using the developed sensor, which confirms that the failure progresses from intralaminar failure modes such as ply splitting in tension. At the same time, delamination leads to kink band formation under compression and the eventual failure of load‐bearing fibers. The developed sensor exhibits repeatable performance with low hysteresis and integrated non‐linearity errors for up to 1000 cycles. The developed sensors could be effectively employed for online in‐situ structural health monitoring of structures in different applications under static and dynamic loading.This article is protected by copyright. All rights reserved.

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Highly Sensitive Flexible Capacitive Pressure Sensor with Porous Hierarchical Structure Realized by a Microwave Curing Method

Ma,

Zhao,

Chen

et al. 2023

Adv Eng Mater

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The introduction of porous hierarchical microstructures effectively improves the sensitivity of flexible capacitive pressure sensors. However, it is still difficult to achieve porous hierarchical microstructures for pressure sensors through inexpensive, efficient, and simple preparation methods. Herein, a hemispherical array with porous hierarchical microstructure was prepared on polydimethylsiloxane (PDMS) substrate by using a simple one‐step microwave curing process with glucose as a porogen. Furthermore, the flexible electrode based on the PDMS substrate was combined with an ionic liquid polymeric gel membrane to obtain a flexible capacitive pressure sensor. Thanks to the deformability of porous hierarchical microstructure and the double dielectric layer effect of ionic liquid polymeric gel membrane, the sensor displays an ultra‐high sensitivity of 131.21 kPa‐1 within the pressure range of 0‐1 kPa. Meanwhile, the sensor has short response time, excellent dynamic loading stability, as well as excellent long‐term stability (>3000 cycles). In application testing, the sensor effectively monitored various physiological activities like pulse, breathe, speech, and swallowing, demonstrating its good prospects in the field of health electronics. Most importantly, the proposed microwave curing method can realize the preparation of porous hierarchical structure on flexible substrate through a one‐step process, which offers a fresh way for the economical, green, and efficient preparation of high‐sensitivity capacitive pressure sensors.A one‐step microwave curing method using glucose as porogen was proposed for preparing porous hierarchical microstructures on PDMS substrate. A highly sensitive flexible piezocapacitive sensor based on porous hierarchical microstructure and an ionic liquid polymeric gel membrane was realized. The piezocapacitive sensor exhibited an ultrahigh sensitivity of 131.21 kPa‐1 and excellent stability over 3000 cycles.This article is protected by copyright. All rights reserved.

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Fabrication of hierarchically porous structured PDMS composites and their application as a flexible capacitive pressure sensor

Cited by 253 publications

References 47 publications

Carbonized Cotton Fabric-Based Flexible Capacitive Pressure Sensor Using a Porous Dielectric Layer with Tilted Air Gaps

Carbonized Cotton Fabric-Based Flexible Capacitive Pressure Sensor Using a Porous Dielectric Layer with Tilted Air Gaps

Additive Manufacturing of Flexible Strain Sensors Based on Smart Composites for Structural Health Monitoring with High Accuracy and Fidelity

Highly Sensitive Flexible Capacitive Pressure Sensor with Porous Hierarchical Structure Realized by a Microwave Curing Method

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