Flexible piezocapacitive sensors based on wrinkled microstructures: toward low-cost fabrication of pressure sensors over large areas

Baek, Seolhee; Jang, Hayeong; Kim, So Young; Jeong, Heejeong; Han, Singu; Jang, Yunseok; Kim, Do Hwan; Lee, Hwa Sung

doi:10.1039/c7ra06997a

Cited by 95 publications

(42 citation statements)

References 31 publications

(47 reference statements)

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“…More importantly, micro-/nano-structure in the elastomeric electrode is thought to be a key element of sensor devices [21][22][23][24], providing faster response time, and higher sensitivity compared to the unstructured electrode [25,26]. Therefore, structured graphene-based sensors have potential to possess superior performance [27].…”

Section: Introductionmentioning

confidence: 99%

Electron-Induced Perpendicular Graphene Sheets Embedded Porous Carbon Film for Flexible Touch Sensors

et al. 2020

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• An efficient method was proposed to prepare perpendicular graphene nano-sheets in flexible sensor electrode. • The nanostructure in carbon electrode was fabricated to further enhance the sensitivity of sensor device using a simple method. • The capacitance showed high performance within only 50-μm dielectric thickness, and an exciting phenomenon of decreasing in capacitance was analyzed. ABSTRACT Graphene-based materials on wearable electronics and bendable displays have received considerable attention for the mechanical flexibility, superior electrical conductivity, and high surface area, which are proved to be one of the most promising candidates of stretching and wearable sensors. However, polarized electric charges need to overcome the barrier of graphene sheets to cross over flakes to penetrate into the electrode, as the graphene planes are usually parallel to the electrode surface. By introducing electron-induced perpendicular graphene (EIPG) electrodes incorporated with a stretchable dielectric layer, a flexible and stretchable touch sensor with "in-sheet-chargestransportation" is developed to lower the resistance of carrier movement. The electrode was fabricated with porous nanostructured architecture design to enable wider variety of dielectric constants of only 50-μm-thick Ecoflex layer, leading to fast response time of only 66 ms, as well as high sensitivities of 0.13 kPa −1 below 0.1 kPa and 4.41 MPa −1 above 10 kPa, respectively. Moreover, the capacitance-decrease phenomenon of capacitive sensor is explored to exhibit an object recognition function in one pixel without any other integrated sensor. This not only suggests promising applications of the EIPG electrode in flexible touch sensors but also provides a strategy for internet of things security functions.

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Section: Introductionmentioning

confidence: 99%

Electron-Induced Perpendicular Graphene Sheets Embedded Porous Carbon Film for Flexible Touch Sensors

et al. 2020

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“…On the other hand, in recent years, a pressure sensor using polymer materials has received much attention among academics and industry due to its unique advantages, including low-temperature processing, low manufacturing costs, mechanical flexibility, and the potential to work in a large area [7,8,12,13,14,15,16,17,18,19,20,21,22,23]. These characteristics indicate the potential to construct the next generation of IoT (Internet of Things) sensing nodes, where the sensor is required to not only be low-power and low-cost, but also, be compatible with many surface types [11,12].…”

Section: Introductionmentioning

confidence: 99%

“…These characteristics indicate the potential to construct the next generation of IoT (Internet of Things) sensing nodes, where the sensor is required to not only be low-power and low-cost, but also, be compatible with many surface types [11,12]. Structurally, the sensor contains an active polymer material layer sandwiched between two electrodes [8,12,13,14,15,16,17,18,19,20,21,22,23]. Based on the physical phenomena of piezoresistivity, piezocapacity, and piezoelectricity, when the applied pressure changes, the resistance, capacitance, or electricity of the sandwiched layer varies, which, in turn, causes the output electrical signal of the device to change.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the physical phenomena of piezoresistivity, piezocapacity, and piezoelectricity, when the applied pressure changes, the resistance, capacitance, or electricity of the sandwiched layer varies, which, in turn, causes the output electrical signal of the device to change. In general, those sandwiched layers are mostly obtained through the use of sensing material system such as a poly(vinylidenefluoride-co-trifluoroethylene (P(VDF-TrFE)), a polydimethylsiloxane (PDMS) or a mixture of polymer and nanoparticles or polymers doped with carbon nanotube [8,12,13,14,15,16,17,18,19,20,21,22,23]. Based on its advantages, the flexible pressure sensor is expected to be used in vehicle detection without damaging the transportation infrastructure, as it can be adhered to the road.…”

Section: Introductionmentioning

confidence: 99%

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A Low-Cost, Flexible Pressure Capacitor Sensor Using Polyurethane for Wireless Vehicle Detection

et al. 2019

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Detection of vehicles on the road can contribute to the establishment of an intelligent transportation management system to allow smooth transportation and the reduction of road accidents. Thus far, an efficient and low-cost polymer flexible pressure sensor for vehicle detection is lacking. This paper presents a flexible sensor for vehicle sensing and demonstrates a wireless system for monitoring vehicles on the road. A vehicle sensor was fabricated by sandwiching a polyurethane material between aluminum top/bottom electrodes. The sensing mechanism was based on changes in capacitance due to variation in the distance between the two electrodes at an applied external pressure. A clear response against a pressure load of 0.65 Mpa was observed, which is the same pressure as that of the car tire area in contact with the road. Significantly, the sensor was easy to embed on the road line due to its mechanical flexibility and large size. A field test was carried out by embedding the sensor on the road and crossing the sensor with a car. Moreover, the signal displayed on the tablet indicated that the sensing system can be used for wireless detection of the axle, speed, or weight of the vehicle on the road. The findings suggest that the flexible pressure sensor is a promising tool for use as a low-cost vehicle detector in future intelligent transportation management.

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“…The most popular structure used in capacitive e-skin is polydimethylsiloxane (PDMS)/Ecoflex dielectric layer sandwiched between two electrodes because of its easiness of preparation and simplicity of data acquisition. 9,10 Previous studies have shown that adding proper microstructures in the dielectric layer can effectively improve the sensitivity of the sensing unit, and different shapes and sizes of microstructure have a significant impact on it as well (flat, 11 trapezoidal, 12 half-cylinder, 13 and pyramids 14 ). However, most research investigated the sensing ability through experiments.…”

Section: Introductionmentioning

confidence: 99%

Modeling and experimental studies of capacitive pressure sensors with microstructured dielectric layers

Zhou

Yan

et al. 2019

Measurement and Control

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Electronic skin (e-skin) has shown great application prospects in many fields due to its multiple advantages. Previous studies have illustrated that the structure with a dielectric layer sandwiched between two electrodes had good pressure-sensing abilities, and microstructures in the dielectric layer could improve the sensitivity. In this paper, we proposed mechanical models of e-skin sensing unit with different microstructures (flat, trapezoidal, half-cylinder, and pyramids) in the dielectric layer. Then, we performed finite element method simulations and experiments to validate the model. Finally, we demonstrated its application as the pressure-sensing unit for human hands, showing its great potentials in sensors of artificial prosthesis or soft robots in the future.

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Flexible piezocapacitive sensors based on wrinkled microstructures: toward low-cost fabrication of pressure sensors over large areas

Abstract: Wrinkled elastomeric templates prepared by stretching and releasing are utilized for demonstrating highly sensitive, simple, and low-cost piezocapacitive pressure sensors over large area.

Cited by 95 publications

References 31 publications

Electron-Induced Perpendicular Graphene Sheets Embedded Porous Carbon Film for Flexible Touch Sensors

Electron-Induced Perpendicular Graphene Sheets Embedded Porous Carbon Film for Flexible Touch Sensors

A Low-Cost, Flexible Pressure Capacitor Sensor Using Polyurethane for Wireless Vehicle Detection

Modeling and experimental studies of capacitive pressure sensors with microstructured dielectric layers

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