Juhwan Park

Microfluidic technologies offer a number of advantages for sample preparation in point-of-care testing (POCT), but the requirement for complicated external pumping systems limits their wide use. To facilitate sample preparation in POCT, various methods have been developed to operate microfluidic devices without complicated external pumping systems. In this review, we introduce an overview of user-friendly microfluidic devices for practical sample preparation in POCT, including self- and hand-ope

This paper presents a pressed paper-based dipstick that enables detection of foodborne pathogens with multistep reactions by exploiting the delayed fluid flow and channel partition formation on nitrocellulose (NC) membrane. Fluid behaviors are easily modified by controlling the amount of pressure and the position of pressed region on the NC membrane. Detection region of the dipstick is optimized by controlling flow rate and delayed time based on Darcy's law. All the reagents required for assay a

A blood cross-matching test should be carried out to prevent a hemolytic transfusion reaction as the final verification step. To simplify complicated procedures of a conventional blood cross-matching test requiring bulky systems and skilled people, we present a finger-actuated microfluidic device for the blood cross-matching test. Although finger actuation is a simple action that anyone can easily accomplish, there would be a variation in the individual finger actuation that may induce the user-

Here, we report an integrated operation of microfluidic pumps and valves only by finger actuation. As the working principle of the finger-actuated microfluidic pumps includes deflection of the poly(dimethylsiloxane) (PDMS) membrane, the pneumatic valves for controlling the flow direction can be easily integrated with the pumps. Using a single button, the flow path can be determined and flow generation can be achieved. We also verified the integrated operation of finger-actuated pumps and valves

Accurate blood typing is required before transfusion. A number of methods have been developed to improve blood typing, but these are not user-friendly. Here, we have developed a microfluidic smart blood-typing device operated by finger actuation. The blood-typing result is displayed by means of microfluidic channels with the letter and the symbol of the corresponding blood type. To facilitate the mixing of blood and reagents, the two sample inlets are connected to a single actuation chamber. Acc

In this paper, we report an analysis of pressed paper in terms of porosity and permeability. Previously, we reported a pressed paper that exhibits decreased porosity and permeability. Additionally, its applications into programmed sample delivery as well as flow rate control were reported. However, there is a need for a theoretical analysis of pressed paper in terms of porosity and permeability for a more precise design principle and its applications because porosity and permeability are importa

Molecular diagnostics can provide a powerful diagnostic tool since it can detect pathogens with high sensitivity, but complicated sample preparation procedures limit its widespread use as an on-site detection tool that relies on the skilled person and external equipment. To resolve these limitations, we report a solid-phase nucleic acid purification using a finger-actuated microfluidic device, which can control a set amount of flow regardless of differences in end-users. To increase the recovery

Poly((D,L)lactic-glycolic)acid-star glucose (PLGA-Glc) polymer-based nanoparticles (NPs) were fabricated for tumor-targeted delivery of docetaxel (DCT). NPs with an approximate mean diameter of 241 nm, narrow size distribution, negative zeta potential, and spherical shape were prepared. A sustained drug release pattern from the developed NPs was observed for 13 days. Moreover, drug release from PLGA-Glc NPs at acidic pH (endocytic compartments and tumor regions) was significantly improved compar

The generation of concentration gradients is an essential part of a wide range of laboratory settings. However, the task usually requires tedious and repetitive steps and it is difficult to generate concentration gradients at once. Here, we present a microfluidic device that easily generates a concentration gradient by means of push-button actuated pumping units. The device is designed to generate six concentrations with a linear gradient between two different sample solutions. The microfluidic

Although immunomagnetic separation is a useful sample pretreatment method that can be used to separate target pathogens from a raw sample, it is challenging to remove unbound free magnetic nanoparticles (MNPs) for colorimetric detection of target pathogens. Here, size-based filtration was exploited for the rapid on-site detection of pathogens separated by immunomagnetic separation in order to remove unbound free MNPs using a finger-powered microfluidic device. A membrane filter and an absorbent

Digital enzyme linked immunosorbent assays (ELISA) can be used to detect various antigens such as spike (S) or nucleocapsid (N) proteins of SARS-CoV-2, with much higher sensitivity compared to that achievable using conventional antigen tests. However, the use of microbeads and oil for compartmentalization in these assays limits their user-friendliness and causes loss of assay information due to the loss of beads during the process. To improve the sensitivity of antigen test, here, we developed a

Although the hanging drop methods have a number of advantages for spheroid culture, they suffer from reagent exchange procedures that depend on tedious and accurate liquid handling by manual pipetting or robotic arms. To simplify these procedures, we developed a method for liquid handling in a hanging drop array (HDA) chip for spheroid culture and analysis by integrating microfluidic channels operated by pushbuttons. Six finger-actuated microfluidic pumping units connected to a 3 × 3 HDA can dra