Resistance-Capacitance Gas Sensor Based on Fractal Geometry

Taicong Yang,Yangfan Huang,James A Covington,Fengchun Tian,Anyan Jiang,Junhui Qian,Yi Xu,Feng Xu,Ran Liu,Zichen Wang

doi:10.3390/chemosensors7030031

Taicong Yang, Yangfan Huang + Show 8 more

Open Access

https://doi.org/10.3390/chemosensors7030031

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Abstract

An important component of any chemiresistive gas sensor is the way in which the resistance of the sensing film is interrogated. The geometrical structure of an electrode can enhance the performance of a gas-sensing device and in particular the performance of sensing films with large surface areas, such as carbon nanotubes. In this study, we investigated the influence of geometrical structure on the performance of gas sensors, combining the characteristics of carbon nanotubes with a novel gas sensor electrode structure based on fractal geometry. The fabricated sensors were tested with exposure to nitric oxide, measuring both the sensor resistance and capacitance (RC) of the sensor responses. Experimental results showed that the sensors with fractal electrode structures had a superior performance over sensors with traditional geometrical structures. Moreover, the RC characteristics of these fractal sensors could be further improved by using different test frequencies that could aid in the identification and quantification of a target gas.

Highlights

Electronic noses (e-nose) are odor-recognizing instruments that consist of an array of gas sensors and pattern recognition algorithm
The gas sensor within the e-nose is one of the most critical components for sensing odors, which is a bottleneck for the sensitivity, precision, and response time of these instruments
Though there are a range of different gas/odor sensors, there are only a few companies which sell chemiresistive sensors that employ a spectrum of detection approaches. This is because many chemiresistive gas sensors do not respond well at low concentrations and have slow response times

Summary

Introduction

Electronic noses (e-nose) are odor-recognizing instruments that consist of an array of gas sensors and pattern recognition algorithm These do not attempt to identify individual chemicals but analyze the sample as a whole, allowing it to chemically sense complex odors that might be challenging when using other techniques. Ort on the design of a new gas sensor structure based on fractal geometry. Studies by GGiuseppe Peano ((118858––1932) [[1199] and David Hilbert (1862–11943)) [20]] have shown that a line segment can be two-dimensional and can fifilll tthhee eennttiirree ppllaannee;;aassiilllluussttrraatteeddiinnFFiigguurree11 This Hilbert curve, which is based on fractal geometry theory, provides new ideas for the design and TmhainsuHfailcbteurrtecuorfvhei,gwhhpicehrfios rbmasaendceoonngfafrrsaaccstetaanllsggoeeroosm,mdeetutrreyy tthoheeiootrsryys, ppercoivaildsetsruncetwuriedeaansdfodritmhendseisoingsn, aconmd pmaraendufatoccttuucroreenvoefnhtiiognhalpeErufocrlimdaeananncceegggeaaossmsseeetnnrysso.orrFss,o, rdduuceaepttaoociittissvespgeecacisiaallsestnrrsuuoccrttsuu,rreethaenndsdpdeciimimaleennfsrsiaioocnntassl,, cdoimepnasrieodntoptorcocvnoivdneevnsetniaotntihoaneloaErluectEilicudacelliabdnaesgaiensofmogreotrhmye.emFtroayrn.cuaFfpoaarcctiuctiarvepeaogcfiautsilvsteran-gsloarssg,estehcnaespsoparcesic,tioatrhlsfer[a2sc1pt]ae.lcOdianiml thefrneascoitonanel dphraimonvdein,desilsoeacnttrphicreoofvireeidltdiecsalilanbetashsebiosertfewotriectehanlebtmhaesainstwuffooarcptuhlareteemsofaonufultfhraaec-ltcauarrpgeaeoccifatouprlatc(rsiath-olorawsrg[n2e1icn]a.

Sensor Measurement

Results and Discussion

Morphology

Conclusions