The Effect of Membrane Thickness on a Microvascular Gas Exchange Unit

Nguyen, Du T.; Leho, Y T.; Esser‐Kahn, Aaron P.

doi:10.1002/adfm.201201334

Cited by 13 publications

(11 citation statements)

References 34 publications

(18 reference statements)

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“…One of the most common wet etchants for PDMS is tetrabutylammonium fluoride (TBAF)—owing to its rapid generation of “naked” fluoride. Previously, researchers controlled the etching rate of PDMS by varying the flow rate and the concentration of TBAF .…”

Section: Introductionmentioning

confidence: 99%

Determination of Factors Influencing the Wet Etching of Polydimethylsiloxane Using Tetra‐n‐butylammonium Fluoride

Kleiman

Ryu

Esser‐Kahn

2015

Macro Chemistry & Physics

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Polydimethyl siloxane (PDMS) is the most widely used polymer in microfl uidic devices. Microfl uidic devices are used in all ranges of science. The microstructure of a microfl uidic device infl uences its effi ciency. One method for controlling microstructure is through wet etching. A particularly common etchant is tetrabutylammonium fl uoride (TBAF). This report shows that the etching rate of PDMS by a TBAF solution is controlled by the solvent in use. This report presents that solvent dictates interplay between the reactivity of the naked fl uoride with the Si O bonds in the polymer chain and the solubility of the polymer chains. Both high reactivity and accessibility are necessary for a high etching rate. This gives a simple method to control the etching rate of PDMS and by that the microstructure of the microfl uidic device.Dr. M. Kleiman, K. A. Ryu, Prof. A. P. Esser-Kahn Chemistry Department Natural Sciences II Irvine, CA 92697 , USA E-mail: aesserka@uci.edu One of the most common wet etchants for PDMS is tetrabutylammonium fl uoride (TBAF) [19][20][21] -owing to its rapid generation of "naked" fl uoride. Previously, researchers controlled the etching rate of PDMS by varying the fl ow rate and the concentration of TBAF. [ 22 ] They reported a maximum increase of 100% in etching rate by increasing fl ow rate as well as a structural change that depended on TBAF concentration. Here we show an increased etching rate of PDMS, up to two orders of magnitude, by changing the solvent. In these experiments, we use circular 3D channels and characterize the etching rate of the channels using TBAF dissolved in 16 common, organic solvents. Etching of PDMS by TBAF is currently thought to be mediated by the attack of the Si -O bonds of PDMS by the naked fl uoride. [23][24][25] The exact mechanism for the reaction between the naked fl uoride and the Si -O bonds remains unknown. From our current etching experiments, we demonstrate that the wide range of PDMS removal rates depends on two factors: (1) the reactivity of TBAF with Si -O bonds in the solvent, which in turn depends on the polarity of the solvent and (2) the degree of solvent swelling of PDMS.

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Section: Introductionmentioning

confidence: 99%

Determination of Factors Influencing the Wet Etching of Polydimethylsiloxane Using Tetra‐n‐butylammonium Fluoride

Kleiman

Ryu

Esser‐Kahn

2015

Macro Chemistry & Physics

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“…Vascular networks have been incorporated into tissue constructs in order to overcome mass transfer limitations 14–16. Tissue engineering scaffolds with pre‐fabricated microvascular networks can dramatically reduce the characteristic length scale for diffusion in bulk materials 17–21. Vascularized scaffolds can accelerate nutrient supply and waste removal in highly metabolically active tissues such as the liver, heart, and kidney 22–24.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the dissociation pathways of metolachlor, acetochlor and alachlor under electron ionization – application to the identification of ozonation products

Bouchonnet

Kinani

Souissi

et al. 2010

Rapid Comm Mass Spectrometry

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With the future aim of using gas chromatography coupled with mass spectrometry to characterize the transformation products of ozonated herbicides: metolachlor, acetochlor and alachlor, an interpretation of their electron ionization mass spectra is presented. Fragmentation mechanisms are proposed on the basis of isotopic labelling and multiple-stage mass spectrometry experiments carried out on an ion trap mass spectrometer. We also give examples in order to demonstrate how the elucidation of such fragmentation mechanisms for herbicides may simplify the characterization of their ozonation products.

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“…Vascular networks reduce the characteristic diffusion length scale and facilitate mass transfer within bulk volumes. Vascularization using microfluidic channels has been utilized in various synthetic materials including cell‐seeded microfluidic scaffolds, gas exchange units, self‐healing polymers, deformable electronics, and actuation of functionality in soft materials . The ideal phase‐change material would be capable of achieving rigid‐compliant transformations that are rapid, reversible, occur at moderate temperatures, and achieve a dynamic range of elasticities that spans at least one order of magnitude.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic Thermally Activated Materials for Rapid Control of Macroscopic Compliance

Balasubramanian

Standish

Bettinger

2014

Adv Funct Materials

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Macroscopic structures that undergo rapid and reversible stiffness transitions can serve as functional polymeric materials for many applications in robotics and medical devices. Thermomechanical phase transitions can provide a suitable mechanism for transient control of mechanical properties. However, the characteristic time scale for actuation is large and dictated by the dimensions of the structure. Embedding vascular networks within bulk polymers can reduce the characteristic length scale of the material and permit rapid and reversible thermomechanical transitions. Here we report perfusable bulk materials with embedded microvascular networks that can undergo rapid and reversible stiffness transitions. Acrylate-based thermoplastic structures exhibit storage moduli with a dynamic range between E’ = 1.02 ± 0.07 GPa and E’ = 13.5 ± 0.7 MPa over time scales as small as 2.4 ± 0.5 s using an aqueous thermal perfusate. The spatiotemporal evolutions of temperature profiles were accurately predicted using finite element simulation and compared to experimental values. Rigid-compliant transitions were leveraged in a demonstration in which a microvascularized device was used to grasp an external object without the aid of moving parts.

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The Effect of Membrane Thickness on a Microvascular Gas Exchange Unit

Cited by 13 publications

References 34 publications

Determination of Factors Influencing the Wet Etching of Polydimethylsiloxane Using Tetra‐n‐butylammonium Fluoride

Determination of Factors Influencing the Wet Etching of Polydimethylsiloxane Using Tetra‐n‐butylammonium Fluoride

Investigation of the dissociation pathways of metolachlor, acetochlor and alachlor under electron ionization – application to the identification of ozonation products

Microfluidic Thermally Activated Materials for Rapid Control of Macroscopic Compliance

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