Improved Stability and Performance of Surface Acoustic Wave Nanosensors Using a Digital Temperature Compensation

S A Moshkalev,J M Rocha,J A L Prestes,A F M De Campos,M R F Hurtado,S M Balashov

doi:10.3389/fsens.2021.617484

Abstract

Surface Acoustic Waves (SAW) sensors are known to be an excellent choice for the measurement of a small concentration of analytes in gas mixtures. The use of this type of sensor has been limited until now in the industrial environment due to the sensitivity of its response to temperature variations. To overcome this problem, thermal stabilization of equipment is normally used. We propose here a simple procedure of compensation of thermal drift in SAW sensors, allowing the measurements to be performed in temperature intervals of up to 20 degrees without any thermal stabilization of the sensitive element of a sensor. By monitoring the temperature of the key points of the sensor and applying the proposed polynomial compensation, it is possible to reduce the influence of thermal instabilities of the ambient temperature to the response more than four times. The method is illustrated by a temperature compensated SAW humidity sensor with a graphene oxide nanofilm as water molecules’ sensitive element. The results show enhanced performance of the sensor over a large temperature interval.

Highlights

Surface Acoustic Wave (SAW) nanosensors for various types of gases with sensitive elements made of nanofilms, such as graphene oxide (Balashov et al, 2013; Xuan et al, 2015), carbon nanotubes decorated with nanoparticles (Sivaramakrishnan et al, 2008), or nanorods of zinc oxide (Wen et al, 2011), present excellent sensitivity and a short response time
We present the algorithm for digital compensation of the temperature contribution to a Surface Acoustic Waves (SAW) sensor response, which opens the possibility to use these devices in various environments when temperatures change during the process of measurements
graphene oxide (GO) is known to be a highly hydrophilic substance, the delay line with such a film turns into a sensitive element of the SAW sensor

Summary

INTRODUCTION

Surface Acoustic Wave (SAW) nanosensors for various types of gases with sensitive elements made of nanofilms, such as graphene oxide (Balashov et al, 2013; Xuan et al, 2015), carbon nanotubes decorated with nanoparticles (Sivaramakrishnan et al, 2008), or nanorods of zinc oxide (Wen et al, 2011), present excellent sensitivity and a short response time. It should be equal to zero (remember that this is the result of measurements for the sensor with two equivalent SAW delay lines and without the sensitive film), but due to different short-term instabilities, it has relatively small peak-to-peak oscillations of 650 Hz. Note that the use of the proposed polynomial approximation reduced the 8 kHz frequency drift (Figure 3A) of the sensor response to a much lower value (Figure 4). Note that the use of the proposed polynomial approximation reduced the 8 kHz frequency drift (Figure 3A) of the sensor response to a much lower value (Figure 4)

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT