Wide range and highly linear signal processed systematic humidity sensor array using Methylene Blue and Graphene composite

Muhammad Umair Khan,Gul Hassan,Mahesh Y Chougale,Rayyan Ali Shaukat,Jungmin Kim,Qazi Muhammad Saqib,Jinho Bae

doi:10.1038/s41598-021-95977-6

Muhammad Umair Khan, Gul Hassan + Show 5 more

Open Access

https://doi.org/10.1038/s41598-021-95977-6

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Abstract

This paper proposes a signal processed systematic 3 × 3 humidity sensor array with all range and highly linear humidity response based on different particles size composite inks and different interspaces of interdigital electrodes (IDEs). The fabricated sensors are patterned through a commercial inkjet printer and the composite of Methylene Blue and Graphene with three different particle sizes of bulk Graphene Flakes (BGF), Graphene Flakes (GF), and Graphene Quantum Dots (GQD), which are employed as an active layer using spin coating technique on three types of IDEs with different interspaces of 300, 200, and 100 µm. All range linear function (0–100% RH) is achieved by applying the linear combination method of nine sensors in the signal processing field, where weights for linear combination are required, which are estimated by the least square solution. The humidity sensing array shows a fast response time (Tres) of 0.2 s and recovery time (Trec) of 0.4 s. From the results, the proposed humidity sensor array opens a new gateway for a wide range of humidity sensing applications with a linear function.

Highlights

This paper proposes a signal processed systematic 3 × 3 humidity sensor array with all range and highly linear humidity response based on different particles size composite inks and different interspaces of interdigital electrodes (IDEs)
The Methylene Blue (MB) and Graphene composite with different particle sizes is utilized in the ratio of 1:1 as following MB and bulk Graphene flakes composite (MB/bulk Graphene Flakes (BGF)), MB and Graphene flakes composite (MB/Graphene Flakes (GF)), MB and Graphene quantum dots composite (MB/Graphene Quantum Dots (GQD))
The terminals of the IDEs are connected with an LCR meter, which reads the impedance of the sensor with a variation of % Relative humidity (RH)

Summary

Introduction

This paper proposes a signal processed systematic 3 × 3 humidity sensor array with all range and highly linear humidity response based on different particles size composite inks and different interspaces of interdigital electrodes (IDEs). It is impossible to fabricate a humidity sensor, that can deliver all the above mentioned parameters In these expectations, for the commercialization of humidity sensors, several researchers are working on different designs based on interdigital electrodes (IDEs)[4], capacitance-based design5, piezoelectric[6], and surface acoustic waves[7]. The proposed sensing array shows fast response time (Tres) and recovery time ( Trec) These results proposes the design and fabrication method of a novel humidity array sensor with linear characteristics on all sensing range

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