Multiwalled carbon nanotube films as small-sized temperature sensors

Abstract

We present the fabrication of thick and dense carbon nanotube networks in the form of freestanding films (CNTFs) and the study of their electric resistance as a function of the temperature, from 4 to 420 K. A nonmetallic behavior with a monotonic R(T)R(T) and a temperature coefficient of resistance around −7×10−4 K−1−7×10−4 K−1 is generally observed. A behavioral accordance of the CNTF conductance with the temperature measured by a solid-state thermistor (ZnNO, Si, or Pt) is demonstrated, suggesting the possibility of using CNTFs as temperature small-sized (freely scalable) sensors, besides being confirmed by a wide range of sensitivity, fast response, and good stability and durability. Concerning electric behavior, we also underline that a transition from nonmetal to metal slightly below 273 K has been rarely observed. A model involving regions of highly anisotropic metallic conduction separated by tunneling barrier regions can explain the nonmetallic to metallic crossover based on the competing mechanisms of the metallic resistance rise and the barrier resistance lowering

Conductive and transparent films of oriented multi-walled carbon nanotubes by Langmuir–Schaefer method

“…However, the greatest slope for the sample transferred at 20 mN m − 1 was observed. The linear decrease of the MWCNT resistance was also observed in this temperature range [28] and confirms the tunneling conduction mechanism as dominant over the pure metallic conduction. The temperature coefficients of resistance (TCR) defined as:…”

Sensing Properties of a Novel Temperature Sensor Based on Field Assisted Thermal Emission

“…The temperature coefficients of Figure 2a were calculated according to equation S = Δ I /(Δ T · I FS ), where Δ T is the variation of temperature, Δ I is the variation of I c , and I FS is the full scale range of I c . The highest coefficient S max was obtained as 0.04 K −1 at 100 °C and 24 V U e (Table 1), higher than the values of other reported CNT-based temperature sensors [1,2,3,4,5]. …”

“…The development goal of a temperature sensor usually includes high sensitivity, small footprint, and low power consumption. The potential of a carbon nanotubes (CNTs) based temperature sensor offers great opportunities towards extreme miniaturization and low power consumption [1,2,3,4,5], thanks to the unique nanoscale structure and electrical property [6,7,8,9,10,11]. Recent studies showed that CNTs could be used to construct temperature sensors.…”

“…Nevertheless, this methodology requires microscopic measurement of the height of the gallium. Alternatively, the CNT-based temperature sensors [2,3,4,5] can also be implemented by measuring the conductivity variation of CNT induced by the thermal interaction. However, the application of this type of sensor is potentially limited by its complex fabrication process and low sensitivity.…”

Skin temperature monitoring by a wireless sensor

“…Their incorporation into polymeric matrices originate nanostructured materials showing new properties [8][9][10]. The fact that CNTs with either semiconducting or metallic character showed an electric resistance strictly dependent on temperature made them interesting for the realization of small-sized temperature sensors [11][12][13][14].…”