Hoon Suk Rho

Maastricht University | UM · Department of Instructive Biomaterials Engineering (IBE)

Self-seeding microwell chips can sort single cells into 6400 wells based on cell size and their identity verified by immunofluorescence staining. Here, we developed a microfluidic device in which these single cells can be placed, lysed and their DNA amplified for further interrogation. Whole blood spiked with MCF7 tumor cells was passed through the...

A new microfluidic valve or a "v-type valve" which can be flexibly actuated to focus a fluid flow and block a specific area of a microchannel is demonstrated. Valves with different design parameters were fabricated by multilayer soft lithography and characterized at various operating pressures. To evaluate the functionality of the valve, single mic...

A microfluidic platform or "microfluidic mapper" is demonstrated, which in a single experiment performs 36 parallel biochemical reactions with 36 different combinations of two reagents in stepwise concentration gradients. The volume used in each individual reaction was 36 nl. With the microfluidic mapper, we obtained a 3D enzyme reaction plot of ho...

A microfluidic platform or “microfluidic batch adsorption device” is presented, which performs two sets of 9 parallel protein incubations with/without adsorbent particles to achieve an adsorption isotherm of a protein in a single experiment. The stepwise concentration gradient of a target protein was created by the integration of microvalves in the...

Worldwide over 5 million children have been conceived using assisted reproductive tech- nology, and research has concentrated on increasing the likelihood of ongoing pregnancy. However, studies using animal models have indicated undesirable effects of in vitro embryo culture on offspring development and health. In vivo, the oviduct hosts a period i...

Organs-on-chips (OoCs) are systems containing engineered or natural miniature tissues grown inside microfluidic chips. To better mimic human physiology, the chips are designed to control cell microenvironments and maintain tissue-specific functions. Combining advances in tissue engineering and microfabrication, OoCs have gained interest as a next-g...

Protein crystallization still remains mostly an empirical science, as the production of crystals with the required quality for X-ray analysis is dependent on the intensive screening of the best protein crystallization and crystal’s derivatization conditions. Herein, this demanding step was addressed by the development of a high-throughput and low-b...

In this work, alveolar‐like microfluidic devices are studied with a horizontal membrane arrangement that demonstrate a great potential as small‐scale blood oxygenator. The design criteria for the fabricated devices are to maximize the oxygen saturation level and minimize liquid chamber volume while ensuring the physiological blood flow in order to...

The complex interaction of cells with biomaterials (i.e., materiobiology) plays an increasingly pivotal role in the development of novel implants, biomedical devices, and tissue engineering scaffolds to treat diseases, aid in the restoration of bodily functions, construct healthy tissues, or regenerate diseased ones. However, the conventional appro...

Microfluidic systems enable automated and highly parallelized cell culture with low volumes and defined liquid dosing. To achieve this, systems typically integrate all functions into a single, monolithic device as a “one size fits all” solution. However, this approach limits the end users’ (re)design flexibility and complicates the addition of new...

A programmable droplet-based microfluidic serial dilutor platform is presented, which is capable of generating a series of droplets with the scalable stepwise concentration gradient of a sample. Sequential dilution of a target molecule was automatically performed in sub-nanoliter scale droplets by synchronizing a microfluidic peristaltic mixer and...

A microfluidic droplet-storage array that is capable of the continuous operation of droplet formation, storing, repositioning, retrieving, injecting and restoring is demonstrated. The microfluidic chip comprised four valve-assisted droplet generators and a 3 × 16 droplet-storage array. The integrated pneumatically actuated microvalves enable the pr...

This paper describes an innovative yet straightforward fabrication technique to create three-dimensional (3D) microstructures with controllable tapered geometries by combining conventional photolithography and thermal reflow of photoresist. Positive photoresist-based microchannel structures with varying width-to-length ratios were reflowed after th...

A microfluidic protein aggregation device (microPAD) that allows the user to perform a series of protein incubations with various concentrations of two reagents is demonstrated. The microfluidic device consists of 64 incubation chambers to perform individual incubations of the protein at 64 specific conditions. Parallel processes of metering reagen...

Here, we report a platform for the specific capture of tdEVs, followed by their in situ characterization using SEM, Raman spectroscopy and AFM, at the single EV level, in terms of size, size distribution and chemical fingerprinting.

Lung disease is one of the most important causes of high morbidity in preterm infants. In this work, we study a simple and easy to fabricate microfluidic device that demonstrates a great potential for blood oxygenation. A meander type architecture with double side vertical membrane arrangement has been selected as reference model to investigate the...

DOI: 10.1002/elps.201700351 The cover picture shows a microfluidic device to investigate drug uptake by single cancer cells. The device is capable of isolating individual cells from a cell suspension into reaction chambers and exposing the cells to different concentrations of a target drug. The potential of the device was demonstrated by showing th...

A microfluidic device for pH gradient chromatofocusing is presented, which performs creation of a micro-column, pH gradient generation, and fraction collection in a single device. Using a sieve micro-valve, anion exchange particles were packed into a microchannel in order to realize a solid-phase absorption column. To fractionate proteins according...

Drug resistance is frequently developing during treatment of cancer patients. Intracellular drug uptake is one of the important characteristics to understand mechanism of drug resistance. However, the heterogeneity of cancer cells requires the investigation of drug uptake at the single cell level. Here, we developed a microfluidic device for parall...

This work proposes a microfluidic gas – ionic liquid contactor for CO2 removal from anaesthesia gas, containing Xe. The working principle involves the transport of CO2 through a polymer flat membrane followed by its capture and enzymatic bioconversion in the ionic liquid solvent. Microfluidic devices enable a rapid and inexpensive screening of pote...

The oviduct hosts the early embryo during the period when its epigenome is completely reprogrammed. Most epigenetic marks are erased, and reacquired as the early cleavage divisions proceed. The role of the oviduct in ensuring the fidelity of reprogramming has been largely neglected when refining in vitro embryo production systems. Our hypothesis wa...

The invention relates to a fluidic device (1) having a particle trap functionality for a particle (2) in a fluid, the fluidic device (1) comprising a first fluid flow channel (11), a second fluid flow channel (12), and a control channel (13), wherein the first fluid flow channel (11) is in fluid contact with the second fluid flow channel (12) and i...

Time-lapse fluorescent images and time courses of HRP reactions. (A) Reactor 1–1 to 1–6, (B) Reactor 2–1 to 2–6, (C) Reactor 3–1 to 3–6, (D) Reactor 4–1 to 4–6, (E) Reactor 5–1 to 5–6, and (F) Reactor 6–1 to 6–6 (200 μm scale bars are shown). (TIF)

Photolithographic mask design (Clewin software) of a microfluidic mapper. (TIF)

Michaelis-Menten equation. (PDF)

Operation of a microfluidic mapper. (AVI)

Off-chip HRP-catalyzed reactions. (A) Standard curve to quantify the concentration of resorufin according to its fluorescence intensity for tracing the product formation in the HRP-catalyzed reaction. The fluorescence intensity of resorufin was measured at various concentrations of resorufin ranged from 10 μM to 60 μM with an increment of 10 μM (n...

Combinations and compositions of reagents for HRP reactions with AR and H2O2. (PDF)

Michaelis-Menten reaction parameters for AR and H2O2 in the various conditions. (PDF)

Image acquisition of 36 reactors. Time interval between two acquisitions of the fluorescent images of neighboring reactors (ΔT) was 3 seconds and between two time-lapse images of the same reactor (Tn+1 –Tn) was 100 seconds for the kinetic study in this work.(A) The moving direction of an automatic stage for scanning 36 reactors, and (B) An example...

Microfluidic devices based on the multilayer soft lithography allow accurate manipulation of liquids, handling reagents at the sub-nanoliter level, and performing multiple reactions in parallel processors by adapting micromixers. Here, we have experimentally evaluated and compared several designs of micromixers and operating conditions to find desi...

Introduction: Genetic and phenotypic characterization of Circulating Tumor Cells (CTC) offer the opportunity for a “real time liquid biopsy”. However, heterogeneity and rarity of CTC command the need for individual cell characterization. Following an enrichment procedure of CTC from blood, the identification, isolation and manipulation of single CT...

A microfluidic chip was designed, prepared and tested for integration with a confocal Raman imaging spectrometer with the special purpose to enable studies of individual biological cells. The design of the chip effectively overcomes the limitations arising from high numerical aperture (NA) and short working distance objectives which are necessary f...

A pneumatically operated peristaltic micro pump can play an important role in nanoliter or picoliter scale fluid handling and delivery for biomimetic micro-scale peristalsis system as well as biological and chemical applications. Here, we first investigate the performance of peristaltic micro peristaltic system that are composed of pneumatically op...

The heterogeneity of tumor cells and their alteration during the course of the disease urges the need for real time characterization of individual tumor cells to improve the assessment of treatment options. New generations of therapies are frequently associated with specific genetic alterations driving the need to determine the genetic makeup of tu...

We present a droplet-based microfluidic platform for carrying out sequential and multiple reactions. Flexible droplet formation, multiple injections of additional droplets into pregenerated droplets, addressing of droplets into incubation chambers, and dosing of additional droplets to incubated droplets were achieved by the forward/reverse flow dir...

The paper reports the development of Lorenz-like chaotic system in an all-fluidic, nanoliter scale, single-phase microfluidic platform. In our system, we have generated the Lorenz-like chaos inside the microchannel using the dynamic flow instability. The flow instability was introduced into an otherwise linear low-Reynolds number microchannel flow...

We report on a highly integrated microfluidic platform with parallel processes for metering, concentration gradient generation, mixing, and optical detection on a single chip. The characteristics of this automated microfluidic system are not only accurate and for rapid analysis of enzyme reaction kinetics according to the nano/picoliters of reagent...

We have investigated the effects of geometry on the mixing performance of peri-staltic micromixers. For the parametric study, we designed and fabricated eleven different mixers, varying the distance between the mixing valves, the mixing valve width, and the mixing loop shape. From the experimental parametric study, we de-rived design guidelines for...