Aging Effects on Oxidized and Amine-Modified Poly(dimethylsiloxane) Surfaces Studied with Chemical Force Titrations: Effects on Electroosmotic Flow Rate in Microfluidic Channels
Bibliographic record
Abstract
Poly(dimethylsiloxane) (PDMS) has been used extensively as a substrate material for microfluidic devices because of its low cost and the ease with which micron-sized features can be molded. PDMS, however, has disadvantages compared to other materials including high hydrophobicity and minimal surface charge. Surface modification by Telsa coil oxidation can be utilized to augment these properties by yielding a hydrophilic surface that is capable of possessing a significant zeta potential at high pH's. However, the modification is only temporary because the hydrophilic surface begins to revert back to its original hydrophobic form, exhibiting a 75% decrease in flow associated with the surface modification in less than 24 h. We show that derivatizing the PDMS surface with (aminopropyl)triethoxysilane following oxidation yields a surface that is more hydrophilic than the native material. Using a combination of chemical force microscopy (CFM) and electroosmotic measurements, we show that this surface is still modified after more than 10 days. We also demonstrate that Tesla coil oxidation, with the inherent damage caused to the surface, is not the only means of oxidizing PDMS. Direct exposure to ozone is also capable of creating a similarly oxidized surface although its ability to support electroosmotic flow is reduced compared to the Tesla coil oxidized surface. The increased stability of the modified surface has ramifications for microfluidic devices constructed from PDMS by enabling the increased control of both magnitude and direction of electroosmotic flow within the device microchannels.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".