Flexible Ecoflex®/Graphene Nanoplatelet Foams for Highly Sensitive Low-Pressure Sensors

Abstract

The high demand for multifunctional devices for smart clothing applications, human motion detection, soft robotics, and artificial electronic skins has encouraged researchers to develop new high-performance flexible sensors. In this work, we fabricated and tested new 3D squeezable Ecoflex® open cell foams loaded with different concentrations of graphene nanoplatelets (GNPs) in order to obtain lightweight, soft, and cost-effective piezoresistive sensors with high sensitivity in a low-pressure regime. We analyzed the morphology of the produced materials and characterized both the mechanical and piezoresistive response of samples through quasi-static cyclic compression tests. Results indicated that sensors infiltrated with 1 mg of ethanol/GNP solution with a GNP concentration of 3 mg/mL were more sensitive and stable compared to those infiltrated with the same amount of ethanol/GNP solution but with a lower GNP concentration. The electromechanical response of the sensors showed a negative piezoresistive behavior up to ~10 kPa and an opposite trend for the 10–40 kPa range. The sensors were particularly sensitive at very low deformations, thus obtaining a maximum sensitivity of 0.28 kPa−1 for pressures lower than 10 kPa.

Waterproof Graphene-PVDF Wearable Strain Sensors for Movement Detection in Smart Gloves

“…Hence, many efforts are devoted to overcome these bottlenecks. Recently, strain sensors-based on the use of electrically conductive polymer composites have attracted great interest due to their light weight, flexibility, easy processing, and cost effectiveness [8]. In particular, the development of new carbon-based conductive nanofillers is fueling the research of graphene-based polymer composites showing a favorable combination of electrical properties with typical features of polymeric materials, such as lightness and easy workability [9][10][11].…”

A Flexible Pressure Sensor with Ink Printed Porous Graphene for Continuous Cardiovascular Status Monitoring

“…Some state-of-the-art pressure sensors based on graphene are compared with this work in Table 1 . It can be seen that, although some materials have high GFs, such as triode-mimicking graphene and graphene nanoplatelet foams, their resolution is not desired to capture small signals [ 16 , 31 ]. On the other hand, despite the graphene oxide sponge having a high resolution, both its GF and detection range are low, which limits its application range compare to the proposed sensor [ 32 ].…”

Recent Progress in Essential Functions of Soft Electronic Skin

“…Traditional conductive elastomer composite consisting of stretchable elastomer and conductive fillers is able to sense the external stress because of the piezoresistive behavior, which can be designed as pressure sensor for the detection of pressure stimuli. [127][128][129][130][131][132][133][134][135][136][137][138][139][140][141][142] However, these pressure sensors normally possess poor sensitivities, obvious hysteresis, and delayed response time, which hinder their practical applications in the e-skins. To overcome the above limitations of traditional pressure sensors, novel geometrical designs of the sensing structures are desired.…”