Session: 17-01-01: Research Posters

Paper Number: 149557

149557 - Towards the Next Generation Portable Optical Device for Single Molecule Analysis 

In recent years, there has been tremendous interest in the potential of manufacturing in-situ portable bio-nanosensor devices for single-molecule analysis without the need for PCR (Polymerase Chain Reaction) amplification. This interest was sparked by the groundbreaking work of Professor Hagan Bayley at the University of Oxford, who successfully demonstrated the electrical detection of single-stranded DNA through the α-hemolysin pore in 2008. Additionally, other scientists have achieved single biomolecule analysis using fabricated SiN nanopore arrays with electrical detection techniques. Despite these advancements, most biosensors rely on optical detection techniques. The development of optical detection devices utilizing surface plasmonic optical effects holds significant promise for industrial applications.

 

In this report, we detail the nanofabrication techniques used to create Au nano-apertures and the subsequent analysis of their optical properties. Initially, a gold film with a thickness ranging from 200 nm to 40 nm was deposited on a SiN/Si substrate using standard sputtering techniques. The gold film was then drilled using a 30 keV Ga Focused Ion Beam (FIB) technique to create nanoscale apertures. These structures were examined using Field Emission Scanning Electron Microscopy (FESEM) and High-Resolution Transmission Electron Microscopy (HR-TEM) to ensure precise fabrication and to study the morphological characteristics of the apertures. The optical properties of the fabricated structures were assessed using a Nikon Inverted Microscope equipped with a Princeton spectrophotometer and a halogen lamp as the light source.

 

To investigate the surface plasmonic interference effect between two nanoslits, we fabricated two nano-slits with widths of approximately 200 nm and varying gap separations of 5, 10, 15, and 20 microns. Additionally, we produced a (7x7) slit array and a (7x7) nano-circular array with varying gap sizes, circular hole diameters, and nanoslit widths ranging from 200 nm down to approximately 10 nm. A nano-slit (7x7) array with a slit width of 10 nm and a separation gap of around 500 nm was also created to explore the effects of extremely narrow slits. Our observations revealed nanoscale Young's plasmonic interference phenomena from the two nanoslits with ~200 nm opening widths, demonstrating clear interference patterns. The (7x7) nanoslit array with slit widths around 20 nm exhibited a broad visible spectrum, indicating strong plasmonic resonance and interference effects.

 

To further validate and optimize the device, we conducted various simulation experiments. Finite-Difference Time-Domain (FDTD) simulations were employed to model the optical response of the nanopore and nanoslit arrays. These simulations helped in visualizing the plasmonic modes and interference patterns, allowing us to correlate the experimental results with theoretical models. Parametric studies were performed to understand how variations in nanoslit dimensions affect the plasmonic interference patterns. Sensitivity analysis was also conducted to evaluate the device's potential for detecting different biomolecules.

 

The developed device shows significant potential for single-molecule optical detection and analysis, offering an alternative to traditional PCR-based methods. By leveraging the unique properties of surface plasmonics, this device can provide high sensitivity and specificity in detecting biomolecules, making it a valuable tool in various applications, including medical diagnostics, environmental monitoring, and biological research. In conclusion, our study demonstrates the successful fabrication and optical characterization of Au nano-apertures for plasmonic biosensing. The observed plasmonic interference effects and the validation through simulation studies highlight the potential of these nanoscale structures in developing advanced biosensing devices. Future work will focus on further optimizing the device design and exploring its practical applications in real-world scenarios.

Presenting Author: Jeong Tae Ok Shawnee State University

Presenting Author Biography: Dr. Jeong Tae (JT) Ok has a diverse background including Mechanical (BS and PhD), Electrical (MS), Electronic (ME), Chemical & Petroleum Engineering (Postdoctoral). He obtained his PhD in the interdepartmental Mechanical and Electrical Engineering programs in Engineering Science at Louisiana State University, Baton Rouge (May 2011). His research has been particularly oriented in the geometrical effects on fluid transportation in micro- and nanofluidics. His doctoral graduate study (supervised by Prof. Sunggook Park) focused on liquid droplet motion on miniaturized asymmetric geometries in extreme-water-repellent conditions such as Leidenfrost (or film-boiling) and superhydrophobic regimes. Before joining the Department of Engineering Technology at Shawnee State University, he was a tenure track Assistant Professor (Mechanical Engineering) at Midwestern State University (MSU Texas). He was a postdoctoral researcher (supervised by Prof. Keith B. Neeves, Chemical & Biological Engineering; and Prof. Xiaolong Yin, Petroleum Engineering) at Colorado School of Mines where he made significant contributions in the field of petroleum fluids transport within artificial porous media analogs while working on RPSEA (Research Partnership to Secure Energy for America) joint project between Colorado School of Mines and Missouri University of Science and Technology. Dr. Ok has been expanding his research subjects such as computational thermo-fluidics; design and hardware implementation of the apparatus for the application of biology, petroleum, energy, and heat transfer; machine learning with humanoid robot via the undergraduate research and senior design projects at MSU Texas, Wright Stat University, and Shawnee State University. His long-term research goal is to contribute in micro- and nanofluidics based thermo-fluidic/biomedical engineering and deep learning oriented biomechanical engineering/design and smart manufacturing while also pursuing extension of his previous and current research. He has 12 refereed journal publications and more than 40 conference presentations including 18 refereed international conference proceedings.

Authors:

Jeong Tae Ok Shawnee State University
Hee Eun Kim National NanoFab Center
Jung Ho Yoo National NanoFab Center
Seong Soo Choi NanoPore Korea