ENGLISH ABSTRACT: Measurement of pressure with zinc oxide (ZnO) nanowires was investigated.
ZnO exhibits the piezoelectric effect, generating a voltage when pressure is
applied to the material. This relationship between pressure and output voltage
was used to make a pressure sensor. A study of the physical and mathematical
working of the piezoelectric effect in ZnO nanowires was done. Simulations
were conducted by means of specialised software to test the theory.
The simulations gave results as the theory had predicted. ZnO nanowires
were grown using various methods. Vapour liquid solid (VLS) was found
to be the best method to grow uniform and dense arrays of ZnO nanowires.
Statistical methods were employed to obtain the optimal parameters for the
growth of ZnO nanowires through the VLS method. After the growth of
the ZnO nanowires a pressure sensor was built. The manufacturing of the
pressure sensor consisted of different steps. The sensors were tested to verify
that they worked as described in theory and as shown in the simulations. The
output voltage was lower than the simulated value due to imperfections and
losses throughout the system. The output voltage versus applied pressure
graphs did coincide with the bulk ZnO materials as well as related products,
such as force sensing resistors. The output voltage is too low, but there are
various methods by which the output voltage can be increased. These methods
are discussed. The finished sensor can be used to continuously monitor
pressure on a plane.
AFRIKAANSE OPSOMMING: Die meting van druk deur sink oksied (ZnO) nanodrade was ondersoek. ZnO
toon die piëzo-elektriese effek - spanning word gegenereer wanneer druk
op die materiaal aangewend word. Hierdie verhouding tussen druk en uitsetspanning
is gebruik om ’n druksensor te vervaardig. ’n Studie van die
fisiese en wiskundige werking van die piëzo-elektriese effek in ZnO nanodrade
is gedoen. Simulasies deur middel van gespesialiseerde sagteware
is uitgevoer om die teorie te bevestig. Die simulasies het resultate getoon
soos deur die teorie beskryf word. ZnO nanodrade is gegroei deur verskillende
metodes. Verdamping vloeistof vastestof (VVV) is as die beste
metode gevind om uniforme en digte skikkings van ZnO nanodrade te kry.
Statistiese metodes is aangewend om die optimale parameters vir die groei
van ZnO nanodrade deur middel van die VVV metode te kry. Na afloop
van die groei van die ZnO nanodrade is ’n druksensor vervaardig. Die vervaardigingsproses
het uit verskillende stappe bestaan, ten einde die bou van
’n werkende druksensor uit die ZnO nanodrade te realiseer. Die sensors is
getoets om te bevestig dat dit werk, soos beskryf deur die teorie en gewys in
die simulasies. Die uitsetspanning was laer as wat verwag was as gevolg van
onvolmaakthede en verliese in die hele stelsel. Die uitsetspanning teenoor
druk grafieke van die sensor het ooreengestem met die van die grootmaat
materiale, asook verwante produkte soos druk sensitiewe weerstande. Die
uitset spanning is baie laag en daar bestaan verskillende maniere waarop die
uitsetspanning verhoog kan word. Hierdie metodes word bespreek.
