Macroporous-Enabled Highly Deformable Layered Hydrogels with Designed pH Response.

Environment-responsive hydrogel structures are of great interest in materials research and have a wide range of applications. By using a flow lithography technique, we report a one-step and high-throughput fabrication method for the synthesis of highly pH-responsive hydrogels with designed shape transformations. In this method, heterogeneous hydrogels with porous and nonporous layers are synthesized using a single UV exposure in a microfluidic channel.

Fabrication of Highly Porous Nonspherical Particles Using Stop-Flow Lithography and the Study of Their Optical Properties.

A microfluidic flow lithography approach was investigated to synthesize highly porous nonspherical particles and Janus particles in a one-step and high-throughput fashion. In this study, using common solvents as porogens, we were able to synthesize highly porous particles with different shapes using ultraviolet (UV) polymerization-induced phase separation in a microfluidic channel. We also studied the pore-forming process using operating parameters such as porogen type, porogen concentration, and UV intensity to tune the pore size and increase the pore size to submicron levels.

Wrinkling Non-Spherical Particles and Its Application in Cell Attachment Promotion.

Surface wrinkled particles are ubiquitous in nature and present in different sizes and shapes, such as plant pollens and peppercorn seeds. These natural wrinkles provide the particles with advanced functions to survive and thrive in nature. In this work, by combining flow lithography and plasma treatment, we have developed a simple method that can rapidly create wrinkled non-spherical particles, mimicking the surface textures in nature.

Functional polymer sheet patterning using microfluidics.

Poly(dimethylsiloxane) (PDMS)-based microfluidics provide a novel approach to advanced material synthesis. While PDMS has been successfully used in a wide range of industrial applications, due to the weak mechanical property channels generally possess low aspect ratios (AR) and thus produce microparticles with similarly low ARs. By increasing the channel width to nearly 1 cm, AR to 267, and implementing flow lithography, we were able to establish the slit-channel lithography.

Effect of needle geometry on flow rate and cell damage in the dispensing-based biofabrication process.

Biodispensing techniques have been widely applied in biofabrication processes to deliver cell suspensions and biomaterials to create cell-seeded constructs. Under identical operating conditions,two types of dispensing needles—tapered and cylindrical—can result in different flow rates of material and different cell damage percent induced by the mechanical forces. In this work, mathematical models of both flow rate and cell damage percent in biodispensing systems using tapered and cylindrical needles, respectively, were developed, and experiments were carried out to verify the effectiveness of the developed models.

Modeling process-induced cell damage in the biodispensing process.

Emerging biomanufacturing processes involve incorporation of living cells into various processes and systems by employing different cell manipulation techniques. Among them, biodispensing, in which the cell suspension is extruded via a fine needle under pressurized air, is a promising technique because of its high efficiency. Cells in this process are continually subjected to mechanical forces and may be damaged if the force or manipulation time exceeds certain levels.