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Title: Design, Simulation and Implementation of All-Printed Sensors
Authors: Awais, Muhammad
Keywords: Engineering And Technology
Electrical Engineering
Issue Date: 2021
Publisher: National University of Computer & Emerging Sciences, Islamabad
Abstract: Printed electronics has gained much interest in last few years for optimization and development of devices that are low-cost, reliable, flexible and compatible with bulk production processes at ambient manufacturing conditions. The expected market share is expected to experience an exponential growth of up to $ 3 billion USD by 2030. Printed electronics majorly focuses on fabrication of highly sensitive and stable, wide range, reliable and ultra-fast responsive electronic sensors to improve overall system performance. Still, there is a need of linear, fast responsive, and bio compatible sensors for wearable and real time monitoring applications. This thesis focuses on modelling and design of device structure through computer aided design (CAD) tools for sensors like humidity, ammonia, bacteria and pressure sensors. Various organic and inorganic materials were synthesized for development of sensors with screen and inkjet printing, spin coating and sputtering techniques incorporated in fabrication process. Substrates such as polyethylene terephthalate (PET), polyethylene 2,6 naphthalate (PEN) and polydimethylsiloxane (PDMS) etc. were employed to attain device flexibility. The fabricated sensors are characterized for their surface, optical, chemical, electrical and mechanical properties for functional verifications. A bimodal simulation analysis is presented for fast detection of bacteria E. Coli in drinking water. Interdigitated electrodes (IDEs) and inductive-capacitive (LC) resonator were simulated on COMSOL multiphysics and Ansys High Frequency Structure Simulation (HFSS), respectively, for voltage-current (VI) and radio frequency (RF) analysis. Upon exposure, an increase in conductance and decrease in capacitance between IDEsis observed compared to ultra-pure water while capacitance shift produces a change in resonance frequency of LC resonator, improving the viii chances of early detection. Similarly, a capacitive three-dimensional (3D) model for ultra-high sensitive pressure sensor was modelled in COMSOL Multiphysics to investigate variation w.r.t. change in distance between electrodes, overlapping area of IDEs, and relative permittivity of piezo-capacitive dielectric. A 300% change was observed via combination of all parametric changes compared to individual change of contributing factors. Modelling and fabrication of fast responsive humidity sensor based on mechanically exfoliated Molybdenum diselenide (MoSe2) nano-flakes is presented after successful development via spin coating MoSe2 on top of screen printed IDEs. Non-linear impedance and capacitance response were observed and recorded between 0–90% relative humidity (RH) range. To linearize response, Polyvinyl Alcohol (PVOH) based sensing layer was developed through spin coating and combined in series with MoSe2 sensor. Approximate linear impedance response was observed and recorded. However, both MoSe2 and PVOH show temperature dependent electrical properties. To minimize temperature dependence, gallium nitride (GaN) based sensing layer was fabricated via Pulse width modulated (PWM) direct current (DC) magnetron sputtering technique. A highly linear and all range impedance response was observed and recorded between 0–100% RH range. Bio-compatibility of GaN allowed its utility at bio-interface as demonstrated in applications like meat quality and plant transpiration monitoring for health and smart agricultural applications.
Gov't Doc #: 23448
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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