Construction of sandwich-like porous structure of graphene-coated foam composites for ultrasensitive and flexible pressure sensors

Nanoscale ◽  
2019 ◽  
Vol 11 (21) ◽  
pp. 10229-10238 ◽  
Author(s):  
Li Zhao ◽  
Fei Qiang ◽  
Shou-Wei Dai ◽  
Shi-Chang Shen ◽  
Yun-Zhuo Huang ◽  
...  

A simple strategy is developed to fabricate ultrasensitive and flexible pressure sensors via constructing a sandwich-like graphene based porous structure.

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 1968 ◽  
Author(s):  
Sylvie Bilent ◽  
Thi Hong Nhung Dinh ◽  
Emile Martincic ◽  
Pierre-Yves Joubert

This paper reports on the study of microporous polydimethylsiloxane (PDMS) foams as a highly deformable dielectric material used in the composition of flexible capacitive pressure sensors dedicated to wearable use. A fabrication process allowing the porosity of the foams to be adjusted was proposed and the fabricated foams were characterized. Then, elementary capacitive pressure sensors (15 × 15 mm2 square shaped electrodes) were elaborated with fabricated foams (5 mm or 10 mm thick) and were electromechanically characterized. Since the sensor responses under load are strongly non-linear, a behavioral non-linear model (first order exponential) was proposed, adjusted to the experimental data, and used to objectively estimate the sensor performances in terms of sensitivity and measurement range. The main conclusions of this study are that the porosity of the PDMS foams can be adjusted through the sugar:PDMS volume ratio and the size of sugar crystals used to fabricate the foams. Additionally, the porosity of the foams significantly modified the sensor performances. Indeed, compared to bulk PDMS sensors of the same size, the sensitivity of porous PDMS sensors could be multiplied by a factor up to 100 (the sensitivity is 0.14 %.kPa−1 for a bulk PDMS sensor and up to 13.7 %.kPa−1 for a porous PDMS sensor of the same dimensions), while the measurement range was reduced from a factor of 2 to 3 (from 594 kPa for a bulk PDMS sensor down to between 255 and 177 kPa for a PDMS foam sensor of the same dimensions, according to the porosity). This study opens the way to the design and fabrication of wearable flexible pressure sensors with adjustable performances through the control of the porosity of the fabricated PDMS foams.


2020 ◽  
Vol 12 (52) ◽  
pp. 58403-58411
Author(s):  
Young-Ryul Kim ◽  
Minsoo P. Kim ◽  
Jonghwa Park ◽  
Youngoh Lee ◽  
Sujoy Kumar Ghosh ◽  
...  

2015 ◽  
Vol 3 (27) ◽  
pp. 5436-5441 ◽  
Author(s):  
Yan-Long Tai ◽  
Zhen-Guo Yang

Flexible pressure sensors are essential components of an electronic skin for future attractive applications ranging from human healthcare monitoring to biomedical diagnostics to robotic skins to prosthetic limbs.


Author(s):  
Qiong Tian ◽  
Wenrong Yan ◽  
Tianding CHEN ◽  
Derek Ho

Pressure sensing electronics have gained great attention in human-machine interface, soft robotics, and wearable biomedical applications. However, existing sensor architectures are inadequate in overcoming the classic tradeoff between sensing range,...


Author(s):  
Xiyao Fu ◽  
Depeng Wang ◽  
Lili Wang ◽  
Hao Xu ◽  
Valerii Shulga ◽  
...  

2017 ◽  
Vol 699 ◽  
pp. 824-831 ◽  
Author(s):  
Yong Quan ◽  
Xiongbang Wei ◽  
Lun Xiao ◽  
Tao Wu ◽  
Hanying Pang ◽  
...  

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7493
Author(s):  
Krystian L. Wlodarczyk ◽  
William N. MacPherson ◽  
Duncan P. Hand ◽  
M. Mercedes Maroto-Valer

In situ measurements are highly desirable in many microfluidic applications because they enable real-time, local monitoring of physical and chemical parameters, providing valuable insight into microscopic events and processes that occur in microfluidic devices. Unfortunately, the manufacturing of microfluidic devices with integrated sensors can be time-consuming, expensive, and “know-how” demanding. In this article, we describe an easy-to-implement method developed to integrate various “off-the-shelf” fiber optic sensors within microfluidic devices. To demonstrate this, we used commercial pH and pressure sensors (“pH SensorPlugs” and “FOP-MIV”, respectively), which were “reversibly” attached to a glass microfluidic device using custom 3D-printed connectors. The microfluidic device, which serves here as a demonstrator, incorporates a uniform porous structure and was manufactured using a picosecond pulsed laser. The sensors were attached to the inlet and outlet channels of the microfluidic pattern to perform simple experiments, the aim of which was to evaluate the performance of both the connectors and the sensors in a practical microfluidic environment. The bespoke connectors ensured robust and watertight connection, allowing the sensors to be safely disconnected if necessary, without damaging the microfluidic device. The pH SensorPlugs were tested with a pH 7.01 buffer solution. They measured the correct pH values with an accuracy of ±0.05 pH once sufficient contact between the injected fluid and the measuring element (optode) was established. In turn, the FOP-MIV sensors were used to measure local pressure in the inlet and outlet channels during injection and the steady flow of deionized water at different rates. These sensors were calibrated up to 140 mbar and provided pressure measurements with an uncertainty that was less than ±1.5 mbar. Readouts at a rate of 4 Hz allowed us to observe dynamic pressure changes in the device during the displacement of air by water. In the case of steady flow of water, the pressure difference between the two measuring points increased linearly with increasing flow rate, complying with Darcy’s law for incompressible fluids. These data can be used to determine the permeability of the porous structure within the device.


2021 ◽  
Author(s):  
Ang Li ◽  
Ce Cui ◽  
Weijie Wang ◽  
Yue Zhang ◽  
Jianyu Zhai ◽  
...  

Abstract Graphene is complexed with cellulose fibers to construct 3D aerogels, which is generally considered to be an environmentally friendly and simple strategy to achieve wide sensing, high sensitivity and low detection of wearable piezoresistive pressure sensors. Here, graphene is incorporated into waste paper fibers with cellulose as the main component to prepare graphene coated waste paper aerogel (GWA) using a simple “filtration-oven drying” method under atmospheric pressure. The GWA was further annealed to obtain the carbonized graphene coated waste paper aerogel (C-GWA) to achieve low density and excellent resilience. The result shows that the C-GWA has a rough outer surface due to the 3D structure formed by interpenetrated fibers and the carbon skeleton with wrinkles. The sensor based on GCA shows low density (25mg/cm3), a wide detection range of 0-132 kPa, an ultra-low detection limit of 2.5 Pa (a green bean, ≈ 53.4 mg), and a high sensitivity of 31.6 kPa− 1. In addition, the sensor based on C-GWA with the excellent performance can be used to detect human motions including the pulse of the human body, cheek blowing and bending of human joints. The result indicates that the sensor based on C-GWA shows great potential for wearable electronic products.


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