Human‐Like Sensing and Reflexes of Graphene‐Based Films

Abstract

Humans have numerous senses, wherein vision, hearing, smell, taste, and touch are considered as the five conventionally acknowledged senses. Triggered by light, sound, or other physical stimulations, the sensory organs of human body are excited, leading to the transformation of the afferent energy into neural activity. Also converting other signals into electronical signals, graphene‐based film shows its inherent advantages in responding to the tiny stimulations. In this review, the human‐like senses and reflexes of graphene‐based films are presented. The review starts with the brief discussions about the preparation and optimization of graphene‐based film, as where as its new progress in synthesis method, transfer operation, film‐formation technologies and optimization techniques. Various human‐like senses of graphene‐based film and their recent advancements are then summarized, including light‐sensitive devices, acoustic devices, gas sensors, biomolecules and wearable devices. Similar to the reflex action of humans, graphene‐based film also exhibits reflex when under thermal radiation and light actuation. Finally, the current challenges associated with human‐like applications are discussed to help guide the future research on graphene films. At last, the future opportunities lie in the new applicable human‐like senses and the integration of multiple senses that can raise a revolution in bionic devices.

Recent Advances in Sensing Applications of Graphene Assemblies and Their Composites

“…However, both CNTs and CNFs have challenges in large‐area devices because of variations in their chirality, difficulty in dispersing, high cost of production, and risk of toxicity, which limit their widespread use . Recently, graphene has gained great interest owing to its unique electronic and mechanical properties and its sensitivity to external stimuli suitable for applications in diverse electromechanical sensors . The high specific surface area along with the 2D geometry of graphene is superior to 1D nanotubes, which is key to enhancing the mechanical properties of polymer composites as compared to CNTs, resulting in better conductive polymer composite (CPC) sensors .…”

A New Strategy for Detecting Plant Hormone Ethylene Using Oxide Semiconductor Chemiresistors: Exceptional Gas Selectivity and Response Tailored by Nanoscale Cr2O3 Catalytic Overlayer

“…a) Dynamic gas‐sensing transients of the 0.3Cr 2 O 3 ‐SnO 2 sensor exposed to 0.1–2.5 ppm ethylene at 375 °C; b) gas response as a function of ethylene concentration and ethylene response reported in literature; [ 25,27–30,47–49 ] c) six repeated measurements of the sensing properties of the sensor to 2.5 ppm ethylene at 375 °C; d) long‐term stability of the sensor over 15 days.…”

“…[ 11 ] However, the required equipment is bulky, expensive, and necessitates the use of time‐consuming gas sampling/pretreatment steps; these factors impede the accomplishment of an instantaneous, portable, and cost‐effective gas monitoring. Therefore, gas sensors using metal oxides, [ 12–19 ] carbon nanotubes (CNTs), [ 20–22 ] and graphene‐based materials [ 23–25 ] have been attracting attention as viable alternatives; this is associated with their high gas response, fast‐responding speed, simple sensor structure, facile miniaturization, and good stability. For the detection of ethylene with low reactivity, metal oxide semiconductors that operate at elevated temperatures (200–400 °C) are more advantageous than CNT‐ and graphene‐based chemiresistors, which are generally operated at room temperature or mildly heated conditions.…”

Ultrahigh Temperature Graphene Molecular Heater

“…Regarding that the electrothermal conversion of the heater is driven by the collision of charged particles in the electric field, also known as Joule heating, the heat performance is determined by the current flow and the intrinsic resistance of it. The extremely high current density (≈2 × 10 9 A cm −2 ) and thermal conductivity (≈5300 W m −1 K −1 ), as well as relatively low thermal loss, where the convective heat‐transfer coefficient is 12.4 W cm −2 °C −1 , of graphene could provide an anticipated heating performance, thus making the graphene molecule a promising building block of the molecular heater. However, the catalytic‐growth characteristic of graphene makes it hard for direct growth on insulated substrate, thus the as‐fabricated films suffer from the significant drawback of low crystallinity and nonuniformity .…”