A Highly Sensitive and Flexible Capacitive Pressure Sensor Based on a Porous Three-Dimensional PDMS/Microsphere Composite

Jung, Young Jin; Lee, Wookjin; Jung, Kyungkuk; Park, Byung-Geon; Park, Jinhyoung; Ko, Jong Soo; Cho, Hanchul

doi:10.3390/polym12061412

Cited by 71 publications

(45 citation statements)

References 41 publications

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“…However, after 30% strain, the difference increased; at 40 °C, the SMP-based sensor showed a fast response time and high sensitivity. The sensitivity can be changed by varying the compressibility, initial porosity, and dielectric constant [ 6 ]. In the case of Figure 4 b, the compressibility is the same because all sensors were compressed under the same strain.…”

Section: Resultsmentioning

confidence: 99%

“…With the increasing demand for wearable devices, pressure sensors that are flexible and sensitive have attracted tremendous attention. Highly sensitive and flexible pressure sensors have great potential for various applications, such as in real time health monitoring [ 1 , 2 , 3 , 4 , 5 ], speech recognition [ 6 ], electronic skin engineering [ 7 , 8 , 9 , 10 , 11 ], and soft robotics [ 12 , 13 , 14 ]. Elastomers, such as polyurethane (PU), polydimethylsiloxane (PDMS), and Ecoflex, are promising materials for these purposes because of their high compressibility, flexibility, and biocompatibility [ 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

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Self-Restoring Capacitive Pressure Sensor Based on Three-Dimensional Porous Structure and Shape Memory Polymer

Park

Jung

et al. 2021

Polymers

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Highly flexible and compressible porous polyurethane (PU) structures have effectively been applied in capacitive pressure sensors because of the good elastic properties of the PU structures. However, PU porous structure-based pressure sensors have been limited in practical applications owing to their low durability during pressure cycling. Herein, we report a flexible pressure sensor based on a three-dimensional porous structure with notable durability at a compressive pressure of 500 kPa facilitated by the use of a shape memory polymer (SMP). The SMP porous structure was fabricated using a sugar templating process and capillary effect. The use of the SMP resulted in the maintenance of the sensing performance for 100 cycles at 500 kPa; the SMP can restore its original shape within 30 s of heating at 80 °C. The pressure sensor based on the SMP exhibited a higher sensitivity of 0.0223 kPa−1 than a typical PU-based sensor and displayed excellent sensing performance in terms of stability, response time, and hysteresis. Additionally, the proposed sensor was used to detect shoe insole pressures in real time and exhibited remarkable durability and motion differentiation.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Self-Restoring Capacitive Pressure Sensor Based on Three-Dimensional Porous Structure and Shape Memory Polymer

Park

Jung

et al. 2021

Polymers

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“…Second, the air gap structure in the dielectric may be advantageous in terms of delaying the pressure-sensing saturation of pressure sensors with a porous dielectric. While the structured pores in the dielectric can lead to wider operating ranges and higher sensitivity in capacitive pressure sensors by increasing the deformability [ 3 , 31 , 39 ], capacitive pressure sensors with porous dielectrics suffer from rapid saturation of the sensing performance [ 14 , 30 ]. It is worth noting that both sensors with an air gap structure (vertical and tilted) exhibited a steady increase in capacitance variations, whereas the pressure sensor with no air gap displayed saturated responses after an applied pressure of 500 kPa.…”

Section: Resultsmentioning

confidence: 99%

“…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%

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.

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“…However, these sensors having a high impedance and are susceptible to electrical interference as they generate signals with a low signal-to-noise ratio [ 18 ]. In some investigations, capacitive sensors have been adopted because of their sensitivity and linearity [ 19 , 20 , 21 , 22 ]. A capacitive sensor based on the copper layer and flexible PCB to be implemented for foot pressure measurement [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

Flexible Ultra-Thin Nanocomposite Based Piezoresistive Pressure Sensors for Foot Pressure Distribution Measurement

Rajendran

Ramalingame

Palaniyappan

et al. 2021

Sensors

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Foot pressure measurement plays an essential role in healthcare applications, clinical rehabilitation, sports training and pedestrian navigation. Among various foot pressure measurement techniques, in-shoe sensors are flexible and can measure the pressure distribution accurately. In this paper, we describe the design and characterization of flexible and low-cost multi-walled carbon nanotubes (MWCNT)/Polydimethylsiloxane (PDMS) based pressure sensors for foot pressure monitoring. The sensors have excellent electrical and mechanical properties an show a stable response at constant pressure loadings for over 5000 cycles. They have a high sensitivity of 4.4 kΩ/kPa and the hysteresis effect corresponds to an energy loss of less than 1.7%. The measurement deviation is of maximally 0.13% relative to the maximal relative resistance. The sensors have a measurement range of up to 330 kPa. The experimental investigations show that the sensors have repeatable responses at different pressure loading rates (5 N/s to 50 N/s). In this paper, we focus on the demonstration of the functionality of an in-sole based on MWCNT/PDMS nanocomposite pressure sensors, weighing approx. 9.46 g, by investigating the foot pressure distribution while walking and standing. The foot pressure distribution was investigated by measuring the resistance changes of the pressure sensors for a person while walking and standing. The results show that pressure distribution is higher in the forefoot and the heel while standing in a normal position. The foot pressure distribution is transferred from the heel to the entire foot and further transferred to the forefoot during the first instance of the gait cycle.

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A Highly Sensitive and Flexible Capacitive Pressure Sensor Based on a Porous Three-Dimensional PDMS/Microsphere Composite

Cited by 71 publications

References 41 publications

Self-Restoring Capacitive Pressure Sensor Based on Three-Dimensional Porous Structure and Shape Memory Polymer

Self-Restoring Capacitive Pressure Sensor Based on Three-Dimensional Porous Structure and Shape Memory Polymer

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

Flexible Ultra-Thin Nanocomposite Based Piezoresistive Pressure Sensors for Foot Pressure Distribution Measurement

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