Enodo Microfluidics Cube

Background

Explore fluid dynamics, mixing, gravitational flow, fluidic resistance and flow rate control in a hands-on modular lab.

Educational Aims

This cube introduces students to the fundamental principles of microfluidics by simulating fluid mixing through pressure-driven flow. Using two coloured dyes, students can observe real-time mixing in a microchannel and relate this to flow velocity, diffusion, and resistance. Students are challenged to design and execute their own experiment plan using the cube and compare mixing outcomes under varying flow rates, gaining critical thinking and problem-solving skills central to real-world science and engineering

Why Microfluidics?

Microfluidics is the study and manipulation of fluids in channels with dimensions of tens to hundreds of micrometres. It's a transformative field in medical diagnostics, drug delivery, lab-on-a-chip devices, and biological research. Microfluidic systems can perform complex processes such as mixing, gradient generation, and separation with minimal volumes and high precision. Some of the transformative applications of microfluidics you might have already encountered include:

Point-of-care diagnostics (e.g., COVID-19 test cartridges)
DNA analysis and sequencing
Organ-on-a-chip devices simulating tissue behaviour
Automated pharmaceutical screening
Cell sorting and manipulation for cell counting

This cube simplifies the complex into an accessible, visual, and interactive experience — a true introduction to hands-on microfluidics.

Materials

1. One Microfluidics Mixer Cube

2. Coloured dyes (e.g., yellow and blue food dye)

3. Two 5–10 mL syringes

4. Tubing compatible with cube inlets and outlet

5. LEGO base or stand (optional but helps stabilize)

6. Ruler or tape measure

7. Collection reservoir

8. Stopwatch or timer

The Experiment

The cube contains a 1 mm x 1 mm cross-section serpentine micro-channel with a total channel length of 3 cm.

I. Assembly

Connect each inlet to a syringe using tubing.
Secure the cube flat on the provided LEGO base.
Fill syringe A with blue dye and syringe B with yellow dye.
Raise the syringes to a height h (e.g., 10 cm above the cube) and allow gravity to feed the dye through.
Connect an outlet tube to a collection container.

II. Flow rate estimation: Use Torricelli’s Law to relate height to velocity and the fluidic resistance of a square channel

III. Observe the mixing visually and estimate the length traveled before full mixing (i.e., transition from distinct streams to a uniform green). Ask students:

Observe how gravitational fluid pressure affects flow rate.
Observe how fluidic resistance affects flow rate.
Does the mixing occur earlier or later at faster flow rates?
How would increasing flow rate affect diffusion time?

IV. Advanced Challenge: Design a gradient generator

Gradient generators create precise dilution profiles and are widely used in pharmaceutical testing, e.g., dosing antibiotics in microdilution assays. So far you have successfully built a simple system that mixes fluids A and B with a 1:1 ratio and sends it to the outlet.

Design Goal: Assemble 6 mixer cubes fluidically to build a gradient generator system. This system would be used to automate the process of mixing fluids A and B with a given ratio. Lets assume our ratio of interest is 1:3. We would like the gradient generator assembly to take the two inlet tubes (fluid A and B) and mix them into 1:3 and 3:1 (A:B) ratio mixtures of A and B, and send these two mixtures to the two outlets.

Your Task