The development of carbon nanostructured sensors

Kritzinger, Pieter Christo (2010-12)

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010.

Thesis

ENGLISH ABSTRACT: During this research the possibility of using carbon nanostructures in sensors were investigated. Graphene and carbon nanotubes (CNTs) are the nano- structures that were used in the developed sensors. Graphene is a single atomic layer of carbon and a carbon nanotube (CNT) is a rolled up sheet of graphene that forms a tube. The unique structure and incredible properties of both these materials make them ideal to be used in sensory applications. A graphene sensor was developed and experiments were performed to determine whether graphene is a viable candidate to be used in a wide range of sensory applications. The graphene sensor operated successfully as a humidity sensor and this led to the discovery that humidity can be used to control the bandgap in graphene. The absorption of CO2 in graphene was successfully measured using surface acoustic waves. As a result, any gas that graphene absorbs can be detected using this method. The use of graphene in three liquid applications was tested. The graphene showed no potential to be used as a pH sensor or as a ow sensor. An experiment was undertaken to determine whether graphene can increase the e ciency of a water electrolysis process, but it was established that the graphene does not make a signi cant di erence. A CNT gas sensor that identi es a gas based on its ionization characteristics was studied and designed. Due to the insu cient height of the grown CNTs, it was decided to focus on the creation of a model of the sensor that can be used to design it optimally. The results of the experiments con rmed that carbon nanostructures such as graphene and CNTs have potential to be used in future sensing applications.

AFRIKAANSE OPSOMMING: Hierdie navorsing ondersoek die moontlikheid om koolstof-nanostrukture in sensor-apparate te gebruik. Grafeen en koolstof-nanobuisies (KNB) is die nanostrukture wat in die ontwikkelde sensors gebruik is. Grafeen is 'n enkel atomiese koolsto agie en KNBs is 'n opgerolde grafeenlagie wat 'n buisie vorm. Die unieke struktuur en ongeloo ike eienskappe van beide hierdie materiale, maak hulle uiters geskik om in sensor-toepassings gebruik te word. 'n Grafeensensor is ontwikkel en eksperimente is uitgevoer om te bepaal of grafeen 'n goeie kanidaat is om in 'n wye verskeidenheid van toepassings gebruik te word. Die grafeensensor is suksesvol aangewend as 'n humiditeitsensor en dit het gelei tot die uitvindsel dat humiditeit gebruik kan word om die energiegaping in grafeen te varieer. Die absorpsie van CO2 in grafeen is suksesvol gemeet deur oppervlak akoestiese golwe te gebruik. Gevolglik kan enige gas wat grafeen absorbeer op hierdie manier gemeet word. Die gebruik van grafeen is in drie vloeistof-toepassings getoets. Die grafeen het geen potensiaal getoon om as 'n pH-sensor of as 'n vloei-sensor aangewend te word nie. 'n Eksperiment is ook uitgevoer om te toets of grafeen die e ektiwiteit van 'n water-elektroliese proses kan verhoog, maar die resultate het gewys dat dit nie 'n wesenlike verskil maak nie. 'n KNB-gassensor, wat 'n gas identi seer uit die ioniseerings eienskappe van die gas, is bestudeer en ontwikkel. Die lengte van die KNBs wat gegroei is, was onvoldoende en daar is gefokus op die ontwerp van 'n model van die sensor wat gebruik kan word om dit optimaal te ontwerp. Die resultate van die eksperimente het bevestig dat koolstof-nanostrukture soos grafeen en KNB baie potentiaal het om in toekomstige sensor-toepassings gebruik te word.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/5389
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