Microfluidics re-imagined in LEGO-style blocks
Microfluidics, and the fluidic logic it embodies, has a history that dates back to (at least) the 1960s. When suitably confined, a moving stream of fluid can exhibit behaviour that can mimic the logic operations familiar from the electrical/electronic domain. Each logic function (gate, flip-flop etc0 has an analogue in the fluid domain. Flip-flops and latches, for example, can be reproduced by wall-attachment devices in which a stream of fluid will “stick” to a certain path through a channel until “flipped” to an alternate route.
Once thought of as a potential mechanism for applications such as industrial control (from a time when microelectronics was considered by some as insufficiently robust for difficult environments), the technology has rarey found application outside certain specialised niches. More recently, it has attracted growing attention for use in biomedical applications. It involves fluid manipulation at the microscale, where the fluid is usually set in motion by pressure regulators or syringe pumps.
The researchers reporting this work are from the Department of Biomedical Engineering, University of California, Irvine. They used polydimethylsiloxane (PDMS) – a silicone-based organic polymer – to cast the building blocks of a truly LEGO-like microfluidics platform. They describe the results of their research in the Journal of Micromechanics and Microengineering (JMM).
Co-author Kevin Vittayarukskul said: “A typical microfluidic device is like a piping network, except the pipes have diameters in the submillimeter range. Our modular system, based on the design of LEGO bricks, allows cheaper and simpler construction of such devices compared to the more traditional fabrication methods like 3D printing or photolithography.
“Our blocks are essentially 2×2 LEGO bricks with integrated microfluidic channels, cast from 3D-printed master moulds and actual LEGO parts. We put the modules together on a standard LEGO plate. Like traditional LEGO bricks, they are stackable, and their geometry makes mass production by injection moulding feasible.”
The image above shows a 3-layer microfluidic assembly. a) An angled view from the top. b) A top-down view. The device is, the authors report, leak-free.
The researchers tested the design by making a range of microfluidic LEGO-like blocks, and building simple microfluidic systems, including 3D configurations. They examined various aspects of the platform, including alignment accuracy, 3D printing dimension fidelity, and burst pressure.
Co-author Professor Abraham Lee said: “Microfluidics systems have a wide range of applications, including point of care diagnostics; ‘smart’ nanomedicine for early detection and treatment; tissue engineering and stem cells; and biosensors to detect environmental and terrorism threats.”
Professor Lee said: “In point of care testing, for example, microfluidics enables the detection of highly dilute compounds, such as rare, blood-borne cancer cells or bacteria. In addition, the miniaturisation enables microfluidic devices smaller than quarters. Compared to traditional methods, these devices also reduce sample volume requirements and speed up sample analysis.
“Despite its potential, microfluidics remains a fairly niche area because of the difficulty in fabrication and assembly. Our system means the creation of custom, 3D microfluidic devices is really as simple as assembling traditional LEGO blocks. The design is simple, usable, and promotes mass production. We hope these features will encourage a broader range of researchers to adopt the technology and explore the possibilities it offers.”
The published version of the paper “A Truly Lego®-like Modular Microfluidics Platform” (Kevin Vittayarukskul et al 2017 J. Micromech. Microeng. 27 035004) can be found at DOI: https://dx.doi.org/10.1088/1361-6439/aa53ed
Information from the Institute of Physics, IOP; www.iop.org
The original work (published paper) acknowledges, “Lego® is the registered trademark of The LEGO Group”
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