Development of a Highly Sensitive, Broad-Range Hierarchically Structured Reduced Graphene Oxide/PolyHIPE Foam for Pressure Sensing

Abstract

Highly sensitive pressure sensors are usually made from soft materials that allow large deformations to be obtained when very small pressures are applied. Unfortunately, this current paradigm limits the ability to create sensors capable of high sensitivities and broad dynamic ranges as these materials are prone to saturation responses when attempting to obtain measurements involving high pressures. In this paper, we detail a piezoresistive pressure sensor that is capable of high sensitivity over a pressure range spanning from 0.6 Pa (a mosquito touching a surface) to 200 kPa (an elephant standing on the surface). The sensor's ability to cover such a broad dynamic range is made possible by the fairly hard foam used in its construction as this material is capable of propagating strain in a highly effective manner due to its hierarchical porous structure. The material was fabricated by using high-internal-phase emulsion (HIPE) as a template to generate a highly porous material consisting of small pores packed between larger ones whose inner walls are lined with reduced graphene oxide. The developed foam exhibits very fast response times (less than 15.4 ms) and excellent cyclic stability (at least 10,000 cycles). Furthermore, it is capable of responding to the entire tactile pressure range, and it can be formatted as pixelated arrays, which makes it highly suitable for integration into wearable electronic devices. Such arrays were built and used to identify and render the shape of objects with different geometries, including a sphere, a triangle, a square, and two nearly identical rods differing only by 0.4 mm in diameter.

1D/2D Nanomaterials Synergistic, Compressible, and Response Rapidly 3D Graphene Aerogel for Piezoresistive Sensor

“…These small sheets and aPAN nanofibers between large layers do not occupy a large amount of interlayer space, but have flexibility and bendability, that enables aPAN nanofibers to act like a spring in adjacent layers. This not only provides enough compressible space for aPANF/GA, but also effectively disperses the external force experienced by the main network scaffold, [ 21 ] allowing it to quickly return to its original state after compression without damaging the structure. Figure 4e,h shows the pore wall, composed of aPAN nanofibers and medium graphene connects parallel layers, the aPAN nanofibers make the pore wall difficult to break when the aPANF/GA is compressed.…”

“…[ 1,2 ] In general, aerogels can be prepared by chemical vapor deposition (CVD), [ 3 ] hydrothermal methods, [ 4 ] and 3D printing, [ 5 ] while they can be prepared form silica, [ 6 ] carbon nanotubes, [ 7 ] graphene, [ 8,9 ] polyimide, [ 10,11 ] Kevlar, [ 12,13 ] and natural materials [ 14–16 ] to name a few. Due to the unique structure and properties of aerogels, they can be utilized for energy storage and conversion, [ 17–19 ] sensors, [ 20,21 ] catalyst support, [ 22,23 ] environmental remediation, [ 24,25 ] and many other diverse applications.…”

Graphene Nanostructure-Based Tactile Sensors for Electronic Skin Applications

“…Reproduced with permission from Ref. [106]. Copyright 2019 American Chemical Society By using a bioinspired hierarchical structure based on the surfaces of organs and consisting of PDMS covered with monolayer graphene (Fig.…”

Untraditional Deformation‐Driven Pressure Sensor with High Sensitivity and Ultra‐Large Sensing Range up to MPa Enables Versatile Applications

“…The larger elastic modulus of PVDF would result in smaller contact area variation and sensitivity compared with PDMS film. Figure 2b illustrates the comparison of our pressure sensors with previously‐reported pressure sensors, [ 40,43,47–52 ] indicating that our sensors possess high sensitivity as well as significantly‐enlarged sensing range. The detectable maximum sensing pressure value of GPVDF pressure sensor could reach up to 1.4 MPa with a higher sensitivity than that of previously reported air‐dielectric graphene transistors.…”