Nano scale devices for plasmonic nanolithography and rapid sensing of bacteria

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Title: Nano scale devices for plasmonic nanolithography and rapid sensing of bacteria
Author: Seo, Sungkyu
Abstract: 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 ?m , 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 .
URI: http : / /hdl .handle .net /1969 .1 /85832
Date: 2008-10-10

Citation

Nano scale devices for plasmonic nanolithography and rapid sensing of bacteria. Available electronically from http : / /hdl .handle .net /1969 .1 /85832 .

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