Low dimensional carbon based materials for low pressure measurement application
Loading...
Date
2015-11-01
Authors
Aniq Shazni Mohammad Haniff
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Advances in materials science and engineering design have enabled the realization of
flexible and highly sensitive pressure sensors. To date, numerous progresses on the invention
of the piezoresistive pressure sensors based on the functional nanomaterials and the
diaphragm structure have been widely demonstrated, in which great attention has been
centered on improvement of sensitivity by the utilization of the functional nanomaterials and
the optimization of the device geometries. However, real-time detection in low pressure
range (<10 kPa) with excellent sensitivity has been rarely reported by the current progress of
piezoresistive pressure sensors due to two apparent reasons: (i) lack of exploitation of
functional nanomaterials through a controllable synthesis method and (ii) implementation of
conventional diaphragm design structure. In view of that, this dissertation is intended to
develop the flexible piezoresistive pressure sensor, which mainly focuses on the sensitivity
enhancement with the incorporation of newly developed low dimensional carbon based
materials and diaphragm structure with IDE array to satisfy the requirement of low pressure
application. The novel features of low dimensional carbon based materials for 0-D carboncapped
nanoparticles, 1-D carbon nanotubes and 2-D graphene ultra-thin films have been
introduced through chemical vapor deposition (CVD) and their morphology and electrical
properties have been carefully characterized. Prior to the device fabrication, analyses on the
characteristics of the reinforced diaphragm structure with interdigitated electrode (IDE) array have been accomplished through the CoventorWare® utilizing the finite element analysis (FEA). Parametric studies have been performed for all the simulations to evaluate the influence of geometrical parameters on the associated characteristics of interest. Two critical steps involved in the development of pressure sensor such as integration of IDE array on
flexible substrate and transfer-printing method of low dimensional carbon based materials
have also been demonstrated. From the characterization results of low dimensional carbon
based materials, uniformity and tunable morphology of the synthesized materials at different
0-D, 1-D and 2-D configuration in a control manner was achieved with excellent electrical
properties. The technical findings highlighted in this study include the successful
demonstration of novel features with mechanism model of carbon-capping in 0-D
nanoparticles, horizontal growth formation in 1-D carbon nanotubes and defects
enhancement in 2-D graphene films by CVD method. For the electromechanical
characterization, it has been demonstrated that the fabricated flexible pressure sensor
incorporated with low dimensional carbon based materials can be operated effectively at
applied pressure below 10 kPa with high sensitivity, high linearity and high gauge factor in a
response to small changes in pressure. The sensitivity of the fabricated sensors with 0-D
carbon-capped nanoparticles, 1-D carbon nanotubes and 2-D graphene ultra-thin films in this research was determined to be 0.0148, 0.0109 and 0.0045 kPa-1 with gauge factor of 186, 136 and 32, respectively, in which outperformed the previous findings reported from the literatures. The results also demonstrated that the pressure sensor incorporated with 0-D
configuration is more sensitive in a response to applied pressure than 1-D or 2-D
configuration, suggesting a significant piezoresistive effect in the reduced dimension. This
outstanding result proved that the low dimensional carbon based materials utilized in this
present study provide the initial platform for further potential research to achieve the target
of ultra-sensitive piezoresistive pressure sensor.