Sang Kyu Kim

We demonstrate nanogap biosensors for electrical and label-free detection of biomolecular interactions. Parallel fabrication of nanometer distance gaps has been achieved using a silicon anisotropic wet etching technique on a silicon-on-insulator (SOI) wafer with a finely controllable silicon device layer. Since silicon anisotropic wet etching resulted in a trapezoid-shaped structure whose end became narrower during the etching, the nanogap structure was simply fabricated on the device layer of a

Utilizing a gold enhancement process after inducing electrostatic interaction between positively charged gold nanoparticles and negatively charged target DNA hybridized to neutral PNA capture probes, a new method for label-free detection of DNA was developed and successfully applied to detect H5-type DNA.

A fully automated point-of-care testing (POCT) system with a surface acoustic wave (SAW) immunosensor was developed for rapid and sensitive detection of cardiac troponin I (cTnI) in body fluid (plasma and whole blood). The assay, based on gold nanoparticle sandwich immunoassay and subsequent gold staining, was performed on the SAW immunosensor packaged inside a disposable microfluidic cartridge. The entire fluidic process, including plasma separation, reagent transport, metering, and mixing, was

A new adaptive <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${h}$ </tex-math></inline-formula> -refinement strategy is investigated for a perfect electric conducting rectangular target using the electric field integral equation. The strategy excludes cells below a specified size from the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notat

For the electrical detection of target DNA (partial avian influenza virus/H1N1/HA sequence) prepared via asymmetric PCR, we fabricated DNA-templated conducting gold nanowire bridges on planar nanogap electrodes using positively charged gold nanoparticles.

Recent advancements in wearable technology, particularly wrist-type electrocardiography (ECG) devices, offer a promising alternative for atrial fibrillation (AF). These devices allow for continuous monitoring but typically require the user to touch an electrode to capture accurate readings. This study introduces a novel photoplethysmography (PPG)/ECG cooperative wearable device that leverages PPG for continuous heart rate (HR) monitoring and ECG for precise AF detection. Beyond sensor developmen

The objective of this dissertation is to develop a reliable and computationally inexpensive adaptive h-refinement technique for the three-dimensional method of moments to reduce numerical errors in electromagnetics efficiently. The adaptive refinement technique consists of an error estimator and a control algorithm. Error estimation plays an important role because it determines regions where error is large. Various error estimators are investigated and implemented. With the Pearson correlation c

Perfect electric conducting (PEC) sectors illuminated by transverse magnetic (TM) and transverse electric (TE) field excitations are studied using the subdomain approach. The subdomain approach, which is similar to the method of overlapping regions (MOR) and the T-block method, requires field expansions in overlapping subdomains and subsequent mode matching. Results for surface current densities are compared with numerical results from COMSOL for problems involving wave scattering from PEC secto

Infinitely thin multiple strip scattering problems are studied using the subdomain approach for two-dimensional (2-D) transverse magnetic and transverse electric excitations. The subdomain approach divides the entire domain into several partially overlapping subdomains, within which fields are expanded by classical techniques. The mode-matching method is used to impose continuity conditions. Results are validated by comparing to numerical results from COMSOL. Results show that the subdomain appr