Single Wall Carbon Nanotubes Based Cryogenic Temperature Sensor Platforms.

Bogdan Florian Monea,Stefan Ionut Spiridon,Eusebiu Ilarian Ionete,Aurel Leca,Anda Stanciu,Ashok Vaseashta,Emil Petre

doi:10.3390/s17092071

Abstract

We present an investigation consisting of single walled carbon nanotubes (SWCNTs) based cryogenic temperature sensors, capable of measuring temperatures in the range of 2–77 K. Carbon nanotubes (CNTs) due to their extremely small size, superior thermal and electrical properties have suggested that it is possible to create devices that will meet necessary requirements for miniaturization and better performance, by comparison to temperature sensors currently available on the market. Starting from SWCNTs, as starting material, a resistive structure was designed. Employing dropcast method, the carbon nanotubes were deposited over pairs of gold electrodes and in between the structure electrodes from a solution. The procedure was followed by an alignment process between the electrodes using a dielectrophoretic method. Two sensor structures were tested in cryogenic field down to 2 K, and the resistance was measured using a standard four-point method. The measurement results suggest that, at temperatures below 20 K, the temperature coefficient of resistance average for sensor 1 is 1.473%/K and for sensor 2 is 0.365%/K. From the experimental data, it can be concluded that the dependence of electrical resistance versus temperature can be approximated by an exponential equation and, correspondingly, a set of coefficients are calculated. It is further concluded that the proposed approach described here offers several advantages, which can be employed in the fabrication of a microsensors for cryogenic applications.

Highlights

Temperature is one of the most important parameters to measure, especially when we refer to the cryogenic field
The sensors were obtained obtained by dropcasting the nanotubes nanotubes sensors with SWCNTs from aa solution solution between between two two electrodes electrodes of of aa support support structure, structure, followed followed by by aa dielectrophoresis dielectrophoresis alignment process process and and high temperature temperature annealing
SWCNTs an exponential exponential established an empirical equation for the sensors characteristics R(T) in the form of an equation, consisting of sum of three exponential terms and one constant

Summary

Introduction

Temperature is one of the most important parameters to measure, especially when we refer to the cryogenic field. Cryogenics is the science of attaining very low temperatures and observing its effect on materials, being widely used in various domains such as aerospace, nuclear, medical, mechanical, chemical, and electrical technologies, or for studying nature. The units used for temperature measurements are Kelvin (K) or Celsius (◦ C). ITS-90 defines the thermodynamic temperature scale from 0.65 K to the highest temperature measurable in terms of the Planck radiation law using monochromatic radiation [1].

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Conclusion