This dissertation contains two different research topics. One is a "Nano Scale Device
for Plasmonic Nanolithography - Optical Antenna' and the other is a 'Nano Scale Device for
Rapid Sensing of Bacteria - SEPTIC'. Since these two different research topics have little
analogy to each other, they were divided into different chapters throughout the whole
dissertation. The 'Optical Antenna' and 'Nanowell / Microwell / ISFET Sensor' represent the
device names of each topic 'Plasmonic Nanolithography' and 'Rapid Sensing of Bacteria'
respectively.
For plasmonic nanolithography, we demonstrated a novel photonic device - Optical
Antenna (OA) - that works as a nano scale object lens. It consists of a number of sub-wavelength
features in a metal film coated on a quartz substrate. The device focuses the incident light to
form a narrow beam in the near-field and even far-field region. The narrow beam lasts for up to
several wavelengths before it diverges. We demonstrated that the OA was able to focus a subwavelength
spot with a working distance (also the focal length) of several µm, theoretically and
experimentally. The highest imaging resolution (90-nm spots) is more than a 100% improvement
of the diffraction limit (FWHM = 210 nm) in conventional optics. A model and 3D
electromagnetic simulation results were also studied. Given its small footprint and subwavelength
resolution, the PL holds great promise in direct-writing and scanning microscopy. Collaborative work demonstrated a Nanowell (or Microwell) device which enables a
rapid and specific detection of bacteria using nano (or micro) scale probe to monitor the electric
field fluctuations caused by ion leakage from the bacteria. When a bacteriophage infects a
bacterium and injects its DNA into the host cell, a massive and transitory ion efflux from the
host cell occurs. SEPTIC (SEnsing of Phage-Triggered Ion Cascade) technology developed by
collaboration uses a nanowell device to detect the nano-scale electric field fluctuations caused by
this ion efflux. The SEPTIC provides fast (within several minutes), effective (living cell only),
phage specific (simple and less malfunction), cheap, compact and robust method for bacteria
sensing. We fabricated a number of devices, including 'Nanowell', 'Microwell' and 'ISFET
(Ion Selective Field Effect Transistor)', which detect bacteria-phage reactions in frequency
domain and time domain. In the frequency domain, detected noise spectrum is characterized by
1/f[beta]. The positive reaction showed much higher [beta] =̃1 than that of background noise or
negative reaction ( [beta] =̃0). For the time domain, we observed abnormal pulses (> 8[omega] ) lasting
0.1 ~ 0.3 s which match the duration of ion flux reported by prior literatures. And the ISFET
showed the phage-infection-triggered pulse in the form of the deviated drain current. Given the
size of nanowell (or microwell, ISFET) and the simplified detection electronics, the cost of
bacteria sensing is significantly reduced and the robustness is well improved, indicating very
promising applications in clinical diagnosis and bio-defense.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/85832 |
| Date | 10 October 2008 |
| Creators | Seo, Sungkyu |
| Contributors | Cheng, Mosong |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, born digital |
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