On-chip development of hydrogel microfibers from round to square/ribbon shape

Abstract

We use a microfluidic approach to fabricate gelatin fibers with controlled sizes and cross-sections. Uniform gelatin microfibers with various morphologies and cross-sections (round and square) are fabricated by increasing the gelatin concentration of the core solution from 8% to 12%. Moreover, the increase of gelatin concentration greatly improves the mechanical properties of gelatin fibers; the Young's modulus and tensile stress at break of gelatin (12%) fibers are raised about 2.2 and 1.9 times as those of gelatin (8%) fibers. The COMSOL simulations indicate that the sizes and cross-sections of the gelatin fibers can be tuned by using a microfluidic device with four-chevron grooves. The experimental results demonstrate that the decrease of the sheath-to-core flow-rate ratio from 150 : 1 to 30 : 1 can increase the aspect ratio and size of ribbon-shaped fibers from 35 μm × 60 μm to 47 μm × 282 μm, which is consistent with the simulation results. The increased size and shape evolution of the cross-section can not only strengthen the Young's modulus and tensile stress at break, but also significantly enhance the tensile strain at break. Disciplines Applied Mechanics | Biology and Biomimetic Materials | Biomechanical Engineering | Polymer and Organic MaterialsComments This is a manuscript of an article published as Bai, Zhenhua, Janet M. Mendoza Reyes, Reza Montazami, and Nastaran Hashemi. "On-chip development of hydrogel microfibers from round to square/ribbon shape."We use a microfluidic approach to fabricate gelatin fibers with controlled sizes and cross sections. Uniform gelatin microfibers with various morphologies and cross sections (round and square) are fabricated by increasing the gelatin concentration of core solution from 8 % to 12 %. Moreover, the increase of gelatin concentration greatly improves the mechanical properties of gelatin fibers; the Young's modulus and tensile stress at break of gelatin (12 %) fiber are raised about 2.2 and 1.9 times as those of gelatin (8 %) fiber. The COMSOL simulations indicate that the size and cross section of gelatin fiber can be tuned by microfluidic device with four-chevron grooves. The experiment results demonstrate that the decrease of sheath-to-core flow-rate ratio from 150:1 to 30:1 can increase the aspect ratio and size of ribbon-shaped fiber from 35 µm × 60 µm to 47 µm × 282 µm, which consists well with the simulation results. The increased size and shape evolution of cross section can not only strengthen the Young's modulus and tensile stress at break, and also significantly enhance tensile strain at break.

Rapid prototyping of microchannels with surface patterns for fabrication of polymer fibers

“…From these devices, polymer fibers were produced according to literature [16], and the process is shown in Figure 4. A solution of 2% Polycaprolactone (PCL) polymer in 2,2,2-Trifluoroethanol (TFE) was used as the core flow and 5% Polyethylene glycol (PEG) in a 1:1 ratio of water and ethanol was used as the sheath flow.…”

“…Recently, researchers have been exploring the possible uses of microfluidics in biomedical diagnostics [9][10][11][12][13][14][15] and biocompatible polymer microfiber fabrication [16][17][18][19][20][21][22][23][24]. Microfluidic diagnostic devices show a lot of promise as they have high portability, reduced analysis time, and inexpensive production compared to benchtop instruments.…”

“…Polymer microfibers can be made by a microfluidic focusing approach, which allows control over the shape and size of the fibers [18,19]. These fibers show promise as substrates for drug delivery [16,19], cell growth [17,19,22], and tissue engineering [19,20]. The high cost and slow production of the popular silicon wafer template for creating microchannels, however, is limiting the expansion of this field.…”

“…This approach is also flexible across various geometries and materials [19,20]. Various shapes of fibers have been reported [16,19,20] with fiber diameters ranging from nanometer scale to several hundred microns [20]. Finally, a single microfluidic channel is capable of creating an assortment of unique fibers by adjusting the flow rates, whereas industrial spinning techniques would require some form of retooling to change the fiber's characteristics [20].…”

Sulfur and Its Role In Modern Materials Science

“…[66,89] Other shapes,w hich are also likely achievable using thiol coupling reactions,h ave been subsequently demonstrated using other reactions and similar microfluidic devices. [99] Wicking,c ell transport, and interlocking capabilities can be Figure 11. Schematic representation showing the modification of ferrocene through thiol-ene and thiol-yner eactions with the resulting possible addition products.…”