Innovative Method Shapes Devices for Studying Liquids Step by Step

When creating devices, engineers typically rely on solids like metal or plastic. However, a team in China has taken a unique approach. They use drops of water as their building blocks to develop a system that can manage and study tiny flows of liquids. The advantage of these new devices is their exceptional ease of assembly, disassembly, and modification.

What inspired this innovative approach? Lego bricks, according to Xin Du, a biomechanical researcher at Southeast University in Nanjing, China, who spearheaded this project.

One day, a student brought his son’s toys to the project, including building blocks that interlock. This sparked Du’s idea to use a similar concept for creating devices. Similar to how Lego bricks can be assembled and reassembled, the idea was to apply this principle to device fabrication.

This concept could be particularly valuable for microfluidics, a field that involves the movement of fluids through tiny tubes. Microfluidics plays a crucial role in various scientific areas, including studying liquid flow through batteries, analyzing chemical reactions, and modeling blood circulation in the body.

The details of this groundbreaking system were published by Du’s team in Nature Chemical Engineering on February 5.

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Innovative Adaptability

The scientists aimed to develop a system that offers easy construction, adjustment, and redesign capabilities—this is known as reconfigurable technology.

By utilizing such systems, researchers can swiftly make alterations when an experimental setup needs adjustment, avoiding the need to start over, as explained by Govind Kaigala, a biomedical engineer at the University of British Columbia in Vancouver, Canada.

For example, researchers can design fluid channels that may require changes in direction. Modifying the pattern, such as altering its orientation, can be seamlessly achieved, Du highlights.

Kaigala emphasizes the hands-on aspect of altering experiments in real-time, a feature especially beneficial in fluid and material reconfigurable systems developed by researchers in his lab.

Dubbed part of a team studying organoids, Du’s group works on artificial organ versions made from cell clusters emulating tissue functionalities. Studying living tissue behavior and responses to stimuli like medication is facilitated by organoids.

While constructing microfluidic devices for liquid flow through organoids is expensive and time-consuming, Du points out. Typically, forming liquid channels involves printing or carving into solid materials, necessitating days to reconstruct any channel changes for new devices, causing experiment delays.

The quest for a reconfigurable system to counter this challenge led the team to the Lego idea. They discovered that the adhesive properties of water droplets mimicked the Lego bricks’ interlocking principle, allowing for easy assembly and disassembly.

Confining Liquids Strategically

The challenge lay in ensuring droplet contact inside a confined space without spillage. The Nanjing team devised a grid equipped with plastic pillars, fabricated using a 3-D printer. Each slender pillar was 5 millimeters tall and 1 millimeter wide, spaced 1 millimeter apart.

Four pillars enclosed a droplet placed amid them, preventing spillage, although the droplet bulged between the pillars. When another droplet was inserted in an adjacent grid space, it adhered in place without spilling over. Upon contact, the droplets merged without overflowing.

Clarifying: What Constitutes 3-D Printing?

Incrementally constructing a continuous liquid path across the maze of pillars, the scientists directed its course methodically. This process is akin to creating a route through a selection of dots in a grid, similar to building a path across the grid.

Initially, the alignment of droplets within the grid posed an issue. Variations in pillar attachment sometimes hindered droplet linkage, Du observed.

To address this, the team immersed the entire grid in silicone oil. The lighter density of oil relative to water caused the droplets to align precisely at the grid bottom.

Varying liquid paths within the grid is feasible. Water can be propelled along a channel via a nozzle at one end, allowing liquid drainage from the opposite end. Adjacent droplets may be separated using a hydrophobic-treated paper, streamlining path changes by removing unnecessary droplets with a dropper.

Diverse Applications

Kaigala expresses enthusiasm for the design’s potential, heralding reconfigurable microfluidics for its versatility and utility across multiple scenarios, making it a sought-after research domain.

The next endeavor for Du’s team focuses on developing narrower channels akin to blood vessel diameters and a silicone oil-free system. These advances aim to broaden the technology’s application scope significantly, Du asserts.

By utilizing charged liquid mediums, researchers could design liquid batteries, among other possibilities. However, Du underscores his primary interest in enhancing organoid design by supplying nutrients or blood to developing cells.

“We’re now capable of creating flexible fluid networks akin to living systems within our bodies,” Du asserts, envisioning the adaptive growth of tools alongside living tissue.