Jeong Hoon Lee

In this paper, we report a new method of fabricating a high-throughput protein preconcentrator in poly(dimethylsiloxane) (PDMS) microfluidic chip format. We print a submicron thick ion-selective membrane on the glass substrate by using standard patterning techniques. By simply plasma-bonding a PDMS microfluidic device on top of the printed glass substrate, we can integrate the ion-selective membrane into the device and rapidly prototype a PDMS preconcentrator without complicated microfabrication

Simple and efficient sample concentration tools are the key to the application of proteomics in a biological system. In this paper, we developed a method to realize a nanofluidic preconcentrator on a poly(dimethylsiloxane) (PDMS)-based microfluidic channel. The originality of our preconcentration device is the simple nanogap formation using the junction gap breakdown phenomenon between two PDMS microchannels, without using any photolithography and etching techniques. From the dc current measurem

A micromachined PZT (52/48) thin film cantilever composed of SiO2/Ta/Pt/PZT/Pt/SiO2 on a SiNx supporting layer for simultaneous self-exciting and sensing was fabricated. We present the resonant frequency change of piezoelectric microcantilevers due to a combination of mass loading and spring constant variation arisen from antigen-antibody interaction of C-reactive protein (CRP). Experimentally measured resonant frequency shift is larger than that of theoretically calculated resonant frequency by

Prominent techniques such as real-time polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and rapid kits are currently being explored to both enhance sensitivity and reduce assay time for diagnostic tests. Existing commercial molecular methods typically take several hours, while immunoassays can range from several hours to tens of minutes. Rapid diagnostics are crucial in Point-of-Care Testing (POCT). We propose an approach that integrates a time-series deep learning

Microfluidic paper-based analytical devices (μPADs) for molecular detection have great potential in the field of point-of-care diagnostics. Currently, a critical problem being faced by μPADs is improving their detection sensitivity. Various preconcentration processes have been developed, but they still have complicated structures and fabrication processes to integrate into μPADs. To address this issue, we have developed a novel paper-based preconcentrator utilizing ion concentration polarization

We report a novel method of increasing both the reaction rate and the sensitivity of low-abundance enzyme assay using a micro/nanofluidic preconcentration chip. The disposable preconcentration device made out of PDMS with a surface-patterned ion-selective membrane increases local enzyme/substrate concentrations for rapid monitoring of enzyme activity. As a model system, we used trypsin as the enzyme and BODIPY FL casein as the fluorogenic substrate. We demonstrated that the reaction rate of tryp

Abstract Since many lateral flow assays (LFA) are tested daily, the improvement in accuracy can greatly impact individual patient care and public health. However, current self-testing for COVID-19 detection suffers from low accuracy, mainly due to the LFA sensitivity and reading ambiguities. Here, we present deep learning-assisted smartphone-based LFA (SMART AI -LFA) diagnostics to provide accurate decisions with higher sensitivity. Combining clinical data learning and two-step algorithms enable

Abstract An essential requirement for bio/chemical sensors and electronic nose systems is the ability to detect the intended target at room temperature with high selectivity. We report a reduced graphene oxide (rGO)-based gas sensor functionalized with a peptide receptor to detect dinitrotoluene (DNT), which is a byproduct of trinitrotoluene (TNT). We fabricated the multi-arrayed rGO sensor using spin coating and a standard microfabrication technique. Subsequently, the rGO was subjected to photo

In this paper, we reported a simple, disposable PDMS micro/nanofluidic preconcentration chip for in vitro concentration-enhanced cell kinase assays. Utilizing the preconcentration (electrokinetic trapping) directly from cell lysate (1 mM ATP) samples, we could achieve at least a 25-fold increase in reaction velocity and 65-fold enhancement in sensitivity. In addition, we shorten the assay time down to less than 10 min, with the sample volume requirements of down to approximately 5 cells. This de

Woodpile metallic photonic crystals are fabricated by using soft lithography and electrodeposition (see figure) for tailored thermal emission. This method produces a highly layered full-metallic structure with excellent structural fidelity. By adding a homogeneous monolithic backplane to the conventional woodpile structure, the difficulty of alignment in layer-by-layer fabrication is alleviated, while preserving characteristic enhanced thermal emission.

The ability to measure pressure and force is essential in biomedical applications such as minimally invasive surgery (MIS) and palpation for detecting cancer cysts. Here, we report a force sensor for measuring a shear and normal force by combining an arrayed piezoelectric sensors layer with a precut glass top plate connected by four stress concentrating legs. We designed and fabricated a thin film piezoelectric force sensor and proposed an enhanced sensing tool to be used for analyzing gentle to