Flexible and Transparent Nanocomposite of Reduced Graphene Oxide and P(VDF‐TrFE) Copolymer for High Thermal Responsivity in a Field‐Effect Transistor

Abstract

3438www.MaterialsViews.com wileyonlinelibrary.com mechanically fl exible, light-weight, inexpensive, and easily attached to a substrate will play an important role in detecting human body temperature and in monitoring perishable food, electronic skins, and in other environmental monitoring applications. [ 3,11,15,18 ] The optical transparency of the fl exible temperature sensor may enable its easy integration into human-friendly, fl exible and transparent electronics. Several types of fl exible temperature sensors such as thermocouples [ 19 ] and resistive temperature detectors [ 15 ] have been developed. Recently, a resistive fl exible Ni composite-based temperature sensor developed by Bao et al. [ 18 ] showed a small dynamic range (25 to 40 °C). Rogers et al. [ 15 ] introduced a class of stretchable temperature sensors based on the temperature coeffi cient resistance (TCR) using serpentine gold and a PIN diode using Si nanoribbons transferred onto microperforated elastomers, which can monitor precise and continuous thermal characterization of human skin. These temperature sensors are not optically transparent because conventional opaque inorganic sensing materials and electrodes were used. Therefore, the development of a fl exible temperature sensor with high responsivity, transparency, ease of integration, large dynamic range, and stability in an ambient environment is an alternative, suitable approach for realizing the stable monitoring of temperature in many fl exible and transparent electronic systems.Graphene (Gr) has exceptional electrical and mechanical properties and has shown interesting stimuli-responsive properties to light, [20][21][22] heat, [ 23,24 ] and strain. [ 12,25,26 ] In addition, graphene and reduced graphene oxide (R-GO) are also known as multi-functional materials with transparency, fl exibility, and stretchability. [27][28][29][30][31][32][33][34] Based on those features, Gr or R-GO is a promising candidate as a physically responsive material for sensing devices. There have been recent reports regarding different types of physically responsive FETs (physi-FETs) for sensing applications based on Gr and R-GO. These include, for example, photodetectors based on mechanically exfoliated Gr and Gr nanoribbons, [ 20,21 ] phototransistors from band gap-tuneable R-GO, [ 35 ] thermal sensors based on a networked R-GO, [ 24 ] and strain sensors based on Gr and R-GO. [ 12,25 ] Although these physical sensing devices make possible new fi elds of applications in electronics, the many processing steps required, such A new class of temperature-sensing materials is demonstrated along with their integration into transparent and fl exible fi eld-effect transistor (FET) temperature sensors with high thermal responsivity, stability, and reproducibility. The novelty of this particular type of temperature sensor is the incorporation of an R-GO/P(VDF-TrFE) nanocomposite channel as a sensing layer that is highly responsive to temperature, and is optically transparent and mechanically fl exible. Furthermore, the...

Transparent Body-Attachable Multifunctional Pressure, Thermal, and Proximity Sensor and Heater

“…The TCR values obtained in the present study are higher than those of graphene-, Au-, and Ag-based thermal sensors, as shown in Fig. 3d [36][37][38] , even though the thermal conductivities of graphene (4800 W…”

Highly Electrocatalytic, Durable, and Stretchable Nanohybrid Fiber for On-Body Sweat Glucose Detection

“…The results and detailed discussion are presented in Figure S9. Based on these results, we can conclude that the temperature does not contribute significantly to the glucose reaction, but the resistance of the fiber decreased as the temperature increased because of the presence of rGO. − …”

A Stretchable Strain-Insensitive Temperature Sensor Based on Free-Standing Elastomeric Composite Fibers for On-Body Monitoring of Skin Temperature

“…However, our results showed an opposite trend, which means that the effect of the thermal expansion of PU on the resistance modulation is not dominant, but the resistance modulation of the rGO nanosheets to temperature changes contributed more. The temperature-dependent electrical behaviors of rGO have been studied in some previous reports. − These studies proved that the resistance change of rGO was attributed to a variable range hopping mechanism at low temperatures and to an Arrhenius-type behavior of charge carrier generation at elevated temperatures. − The conductivity of the FSSFs increased with increases in the temperature because of the enhancement of the charge transport inside the rGO sheet and between the rGO sheet junctions, as well as the generation of charge carriers in the rGO nanosheets under thermal stimulus. ,,, Furthermore, the responsivity of FSSFs gradually increased as the reduction time decreased from 7 h to 1 h 10 min. These results are attributed to the change in the density of oxygen-containing functional groups on the rGO in the fibers.…”

“…40−43 The conductivity of the FSSFs increased with increases in the temperature because of the enhancement of the charge transport inside the rGO sheet and between the rGO sheet junctions, as well as the generation of charge carriers in the rGO nanosheets under thermal stimulus. 7,24,44,45 Furthermore, the responsivity of FSSFs gradually increased as the reduction time decreased from 7 h to 1 h 10 min. These results are attributed to the change in the density of oxygen-containing functional groups on the rGO in the fibers.…”