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Phase 1 — Learning the Limits of Additive Manufacturing
Phase 1 — Learning the Limits of Additive Manufacturing
Our journey began with an ambitious goal: reproducing the performance of available commercial microfluidic chips using affordable resin 3D printing.
Commercial devices typically use enclosed channels as small as 0.3 mm, which exceeded the capabilities of our printing process at that time. Fully enclosed microchannels of this size could not be reliably fabricated, and trapped resin frequently cured inside the channels, causing blockages.
Rather than abandoning the project, we turned the challenge into an opportunity to better understand the manufacturing limits of our system.
Phase 2 — Characterizing the Manufacturing Process
Phase 2 — Characterizing the Manufacturing Process
A series of test structures was designed to determine the minimum printable channel dimensions.
These experiments revealed that enclosed channels with diameters of approximately 1.0 mm could be fabricated consistently and repeatedly. This became the design foundation for our first generation of microfluidic devices.
By establishing reliable manufacturing parameters, we were able to move from prototyping toward practical applications.
Phase 3 — First Functional Liposome Production Chip
Phase 3 — First Functional Liposome Production Chip
Our first successful microfluidic chip for liposome production featured:
Two inlets
One outlet
A serpentine mixing channel
Fully enclosed internal flow paths
The device successfully demonstrated liposome production but was relatively large, requiring significant amounts of resin and long printing times.
Although functional, it was clear that the design needed to become more compact and efficient.
Phase 4 — Miniaturization and Process Optimization
Phase 4 — Miniaturization and Process Optimization
The second-generation chip maintained the proven 1.0 mm channel diameter while significantly reducing the overall device size.
This redesign provided several advantages:
Reduced material consumption
Shorter printing times
Lower manufacturing costs
Easier handling
At this stage, we also began exploring internal geometries intended to enhance mixing by introducing local flow disturbances within the channels.
Phase 5 — Understanding Flow Distribution
Phase 5 — Understanding Flow Distribution
Testing revealed an important limitation of the previous architecture.
Because of the channel arrangement, portions of the fluid tended to follow preferential flow paths, reducing mixing efficiency and limiting the effectiveness of the internal structures.
This observation led to a complete redesign of the flow network with the objective of improving flow distribution and minimizing preferential pathways.
Additional internal mixing features were also investigated to further increase contact between the fluid phases.
Phase 6 — The Channel Size Challenge
Phase 6 — The Channel Size Challenge
Despite the improvements in mixing performance, a major obstacle remained.
Commercial microfluidic systems operate with channels significantly smaller than 1.0 mm. To achieve similar performance, channel dimensions needed to be reduced.
However, the enclosed-channel manufacturing approach imposed a practical limit. As channels became smaller, uncured resin became trapped inside the device and could not be removed effectively. During post-processing, this trapped resin often cured and permanently blocked the channels.
Lower-viscosity resins improved the situation but did not completely solve the problem.
A different approach was required.
Phase 7 — Transition to Open-Channel Manufacturing
Phase 7 — Transition to Open-Channel Manufacturing
To overcome the limitations of enclosed printing, we developed an open-channel architecture.
Instead of printing closed microchannels directly, channels were printed open and sealed afterward.
This strategy dramatically improved manufacturing resolution and allowed us to reduce channel dimensions from 1.0 mm to approximately 0.4 mm, approaching the 0.3 mm scale commonly found in commercial devices.
This milestone represented a significant advancement in our fabrication capabilities.
Phase 8 — Developing a Reliable Sealing Method
Phase 8 — Developing a Reliable Sealing Method
The new challenge became sealing the open channels.
Our initial solution used adhesive polymer films to close the microfluidic network.
While simple and inexpensive, early versions experienced several issues:
Film delamination during operation
Bubble formation beneath the sealing layer
Leakage at higher flow rates
Possible chemical interactions with alcohol-containing formulations
Extensive testing suggested that local pressure increases and deformation of the flexible film were major contributors to failure.
Through iterative redesign of both the chip geometry and operating conditions, sealing reliability improved substantially.
An additional observation was that allowing the adhesive film to cure and stabilize on the chip for several days before use significantly enhanced bonding performance.
Phase 9 — Current Generation
Phase 9 — Current Generation
The current generation combines the lessons learned throughout every stage of development:
High-resolution open-channel fabrication
Approximately 0.4 mm microchannels
Reduced material consumption
Improved flow distribution
Enhanced mixing structures
Reliable film-based sealing strategy
Compatibility with liposome production workflows
The result is a cost-effective, rapidly manufactured microfluidic platform that continues to evolve toward higher performance and greater manufacturing precision.
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