Development of Novel Biosensing Platforms using Metal, Metal-Insulator-Metal (MIM) and Quantum Materials
Creators: NANDI, DIPANJAN
Publisher: name: University of Alberta Library
Year: 2024

<p>Rapid and accurate testing of easily transmissible diseases is essential to prevent<br>
extensive breakouts, identify infected individuals for timely treatment, and curb<br>
transmission by taking suitable measures. With the advancement of nanotechnology,<br>
biosensors are becoming an indispensable tool in drug development, biomedicine,<br>
disease monitoring, and food safety. Nanophotonic biosensors rely on the interaction of the evanescent field with target bioanalytes to produce a measurable optical signal output. This thesis is a groundbreaking achievement in the field of<br>
nanoresonator-based biosensor platforms. Through the use of finite-difference timedomain (FDTD) simulations, we have developed three distinct designs that incorporate metal-insulator-metal (MIM), gold (Au), and 2D material nanoresonators. These<br>
designs have the potential to revolutionize the biosensor industry and pave the way<br>
for new and innovative applications.<br>
The design of two different MIM nanoresonator configurations, (i) metal-insulatormetal nanopillar array and (ii) metal nanoresonator array on insulator-metal thin<br>
film stack, were nurtured. The influence of the geometric parameters such as diameter, pitch, insulator layer’s materials and thickness, the shape of individual nanoresonators, and the array arrangements were cultivated efficiently to balance the leakiness of MIM nanoresonators for achieving high surface sensitivity. With the best design parameters, MIM nanoresonators were fabricated and experimentally validated<br>
with varying concentrations of polystyrene beads. The MIM nanopillar array device<br>
demonstrated the best experimental detection sensitivity of 6.54 ± 0.7 nm/decade<br>
for polystyrene beads of 100 nm diameter. Polystyrene beads were used to test the device’s performance as their optical properties, such as refractive index and extinction coefficient, match well with most bioanalytes.<br>
Despite the high degree of tunability of localized surface plasmon resonance field,<br>
the fabrication complexity associated with different MIM nanoresonators imposes<br>
limitations for mass production and cost-effectiveness. In this context, plasmonic<br>
Au nanoresonators were proposed, and the best design was established using FDTD<br>
simulation to enhance the localized surface plasmon resonance (LSPR) field. The<br>
devices were fabricated with the best design parameters and were biofunctionalized,<br>
demonstrating SARS-CoV-2 detection with one of the lowest limits of detection 1<br>
virus-like particle (VLP) µL−1 and detection sensitivity of 1.32 ± 0.08 nm/decade.<br>
We also proposed a design of a portable point-of-care biosensing platform using our<br>
Au nanoresonators.<br>
Furthermore, we delved into different metasurface designs of MoS2 nanoresonators<br>
to mitigate the field dissipation issues that plague the plasmonic metal nanostructures. We introduced three groundbreaking MoS2 nanoresonator designs for biosensor<br>
platforms, established novel fabrication methods and experimentally evaluated their<br>
performances. MoS2 was selected as the material for the nanoresonator due to its<br>
high refractive index and low absorption coefficient in the visible wavelength range.<br>
Moreover, MoS2 has minimal cytotoxicity and biocompatibility, making it suitable for<br>
various biosensing applications. The best design obtained from FDTD simulations<br>
were utilized to fabricate nanoresonators with the large area (1 inch × 1 inch) MoS2<br>
thin film grown by pulsed laser deposition system. The experimental measurements<br>
provided a detection sensitivity of 13.71 ± 1.7 nm/decade and a limit of detection<br>
(LOD) of 4 polystyrene beads.<br>
By innovating three distinct nanophotonic platforms, we have showcased the adept<br>
detection of 100 nm-sized polystyrene beads and SARS-CoV-2 virus-like particles.<br>
This thesis research not only underscores the accomplishment of nanophotonics but<br>
also symbolizes its profound capacity to make a monumental impact in biosensing.<br>
Our ingenious approach has demonstrated capability and illuminated a path<br>
where nanophotonics emerges as a transformative force, fundamentally reshaping the<br>
biosensing landscape with unparalleled precision and efficacy.</p>