Why You Should Think Twice Before Using PDMS in Microfluidic
PDMS (Polydimethylsiloxane) has been the go-to material in academic microfluidics. Its low cost, optical clarity, and ease of prototyping via soft lithography made it the standard in university labs.
But times have changed. In industrial, diagnostic, and even biological applications, Polydimethylsiloxane is increasingly seen as obsolete, due to a combination of physical limitations, poor reproducibility, and lack of scalability.
In this article, we highlight why PDMS might be failing you, and introduce Flexdym: a new-generation elastomer designed specifically for microfluidics.
The Hidden Disadvantages of PDMS in Microfluidics
It Absorbs Small Molecules
Polydimethylsiloxane is highly permeable and absorbs small hydrophobic molecules like fluorescein, hormones, drugs, and solvents.
This leads to loss of analytes, signal dampening, and inaccurate results.
It’s especially problematic for quantitative assays, drug screening, or single-cell analysis.
Toepke & Beebe (2006) showed that over 90% of Rhodamine B was absorbed into PDMS within 24 hours.
It is Not Scalable
Soft lithography with Polydimethylsiloxane involves manual pouring, degassing, curing, cutting, aligning, and bonding. This is fine for academic prototyping, but not for industrial or clinical manufacturing.
Batch-to-batch variation is high.
Human handling increases contamination risk.
Cleanroom-free production is difficult.
Berthier et al. (2012) concluded that “PDMS is not suitable for high-throughput or mass production.”
Hydrophobic Recovery Ruins Surface Treatments
PDMS can be temporarily hydrophilic after plasma treatment, but this effect vanishes in hours. This makes surface functionalization unstable, impacting cell adhesion, droplet generation, and capillary flow systems.
Bonding & Microfabrication = Time Consuming
PDMS requires plasma treatment or surface activation for bonding, procedures that are time-sensitive, often irreversible, and hard to scale.
Bond strength degrades over time.
Plasma bonding must occur within minutes after treatment.
Manual alignment of layers increases error rates.
It Leaches Oligomers
One often overlooked problem with Polydimethylsiloxane is that it leaches unreacted oligomers into surrounding media. These low-molecular-weight silicone species can:
Contaminate cell cultures or samples
Interfere with assays and fluorescence
Compromise results in toxicology and drug testing
It is not fully crosslinked during curing; residual oligomers can diffuse out over time, especially under thermal or chemical stress (e.g., in incubators or under solvents).
Regehr et al. (2009) showed that PDMS oligomers leached into media and altered gene expression in cultured cells.
Meet Flexdym: The Alternative to PDMS You’ve Been Waiting For
| Features | Polydimethylsiloxane | Flexdym |
|---|---|---|
| Absorption of hydrophobic molecules | High | Low |
| Reusability | Low | High |
| Bonding | Plasma | Room Temperature, Thermal, Plasma |
| Production scale | Time consuming - Soft Lithography, 3D Printing | Few minutes - Hot embossing, R2R, Injection molding, 3D Printing |
| Optical clarity | High | High |
| Gas permeability (O2 / CO2) | High | Low ; tunable |
| Autofluorescence | Low | None |
Use Cases Where Flexdym Shines
Organ-on-a-chip
Wearable Devices
Diagnostics (e.g. Lateral Flow, Point-of-Care)
Cell culture and tissue engineering
- Multi-layer devices
PDMS vs Flexdym in the Lab and Beyond
With hot embossing systems like SUBLYM, Flexdym can be rapidly molded into complex microfluidic chips without cleanroom steps. Flexdym chips are reusable, reproducible, and scalable from R&D to production bridging the gap Polydimethylsiloxane never could.
Ready to Move Beyond Polydimethylsiloxane?
Whether you’re prototyping or scaling up, Flexdym offers a drop-in replacement for Polydimethylsiloxane that supports your project’s future.
Explore Flexdym kits, molding tools, and design support at Eden Tech.
References
Want to Try Flexdym?
Get your Flexdym starter kit, access our free design tool FLUI’DEVICE, or ask for a demo. Stop prototyping in a dead-end , switch to Flexdym and build the future of microfluidics.
