‘Microfluidic Chip’ Used for Cancer Cell Diagnosis, Breakthrough Technology Developed to Control Substance Transport Using Only Evaporation Phenomenon

UNIST Professor Kim Taesung's Team Controls Delivery of Drug-like Small Molecules Without Power or External Stimuli

Applicable to Diagnostic and New Drug Development Chip Technologies... Published in Nature Communications

From the left, UNIST Professor Kim Taesung, Researcher Seo Sangjin, Researcher Ha Dokyung.

[Asia Economy Yeongnam Reporting Headquarters Reporter Kim Yong-woo] A groundbreaking technology that maximizes the efficiency of 'microfluidic chips' used for cancer cell diagnosis and other applications has been developed by a domestic research team.

Microfluidic chips for detecting pathogens or diagnosing cancer cells require a nanofilm filter to separate liquid samples and a driving device or chemical stimuli to control the flow of the samples. However, problems arise such as having to produce a new microfilm filter each time it is used or sample damage caused by failure to control the stimuli.

Professor Kim Tae-sung's team from the Department of Mechanical Engineering at Ulsan National Institute of Science and Technology (UNIST, President Lee Yong-hoon) developed a new technology that can control the input of small molecules such as drugs, neurotransmitters, and DNA fragments by the evaporation phenomenon of the liquid (solvent) inside the microfluidic chip without damaging the sample.

Unlike existing methods, this technology does not require separate driving devices or strong stimuli, so it does not damage the sample. It is attracting great attention as a versatile control core technology capable not only of filtering or valve functions to separate samples but also of concentration and pumping functions.

Professor Kim's team utilized the phenomenon where liquid flow is drawn toward the side where evaporation occurs to fill the empty space when liquid evaporates from the tiny gaps on the wall surface of the nanoslit, which is part of the microfluidic channel.

A research illustration showing the simultaneous control of material transport using multiple nanoslit structures.

The principle is that the sample contained in the liquid gathers or diffuses in one place depending on the direction of the liquid flow.

The height of the nanoslit channel is only a few nanometers (10^-9 m), which is very low, while the cross-sectional length is in the micrometer (10^-6 m) range, maximizing changes in fluid flow caused by evaporation.

Except for humidity changes to control evaporation, no external stimuli are needed, and nanoslits can be easily fabricated through crack-photolithography.

Crack-photolithography is a modified photolithography process commonly used in semiconductor manufacturing, which the research team had already developed in previous studies.

The researchers fabricated a microfluidic chip where two main chips (a source chip and a target chip) are connected by a nanoslit, proving that the nanoslit can function as a valve or filter that concentrates samples or controls sample injection into the target chip.

They achieved concentration of the sample (fluorescent molecules) to 256 times the concentration of small molecules in the source chip within just one hour.

Research illustration verifying pump and filter functions using evaporation phenomena of nanoslit.

Professor Kim said, “The technology for controlling small molecule delivery in microfluidic environments is a highly impactful research area attracting attention not only in the bio field but also in energy synthesis and desalination.”

Seo Sang-jin, first author and integrated master's and doctoral course researcher in the Department of Mechanical Engineering at UNIST, explained, “In this study, fluorescent signal-emitting molecules were used as samples to observe material transfer phenomena, but this technology can also be applied to micro substances such as drugs, neurotransmitters, DNA fragments, and quantum dots.”

The research team plans to collaborate with researchers in other fields to further demonstrate the performance.

This study was published online on February 26 in the prestigious multidisciplinary international journal Nature Communications. The research project was supported by the Ministry of Science and ICT and the National Research Foundation of Korea.

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