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Writing in the granular gel medium.

Bhattacharjee T, Zehnder SM, Rowe KG, Jain S, Nixon RM, Sawyer WG, Angelini TE - Sci Adv (2015)

Bottom Line: This physical approach to creating three-dimensional (3D) structures negates the effects of surface tension, gravity, and particle diffusion, allowing a limitless breadth of materials to be written.We crosslinked polymeric materials and removed them from the granular gel, whereas uncrosslinked particulate systems were left supported within the medium for long times.This approach can be immediately used in diverse areas, contributing to tissue engineering, flexible electronics, particle engineering, smart materials, and encapsulation technologies.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA.

ABSTRACT
Gels made from soft microscale particles smoothly transition between the fluid and solid states, making them an ideal medium in which to create macroscopic structures with microscopic precision. While tracing out spatial paths with an injection tip, the granular gel fluidizes at the point of injection and then rapidly solidifies, trapping injected material in place. This physical approach to creating three-dimensional (3D) structures negates the effects of surface tension, gravity, and particle diffusion, allowing a limitless breadth of materials to be written. With this method, we used silicones, hydrogels, colloids, and living cells to create complex large aspect ratio 3D objects, thin closed shells, and hierarchically branched tubular networks. We crosslinked polymeric materials and removed them from the granular gel, whereas uncrosslinked particulate systems were left supported within the medium for long times. This approach can be immediately used in diverse areas, contributing to tissue engineering, flexible electronics, particle engineering, smart materials, and encapsulation technologies.

No MeSH data available.


Related in: MedlinePlus

Granular gel as a 3D writing medium.(A) A microscale capillary tip sweeps out a complex pattern as material is injected into the granular gel medium. Complex objects can be generated because the drawn structure does not need to solidify or generate support on its own. (B) As the tip moves, the granular gel locally fluidizes and then rapidly solidifies, leaving a drawn cylinder in its wake. The reversible transition allows the tip to traverse the same regions repeatedly. (C) The soft granular gel is a yield stress material, which elastically deforms at low shear strains and fluidizes at high strains. (D) Stress-strain measurements reveal a shear modulus of 64 Pa and a yield stress of 9 Pa for 0.2% (w/v) Carbopol gel. (E) The cross-sectional area of written features exhibits nearly ideal behavior over a wide range of tip speeds, v, and flow rates, Q. The trend line corresponds to the volume conserving relationship, .
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Figure 1: Granular gel as a 3D writing medium.(A) A microscale capillary tip sweeps out a complex pattern as material is injected into the granular gel medium. Complex objects can be generated because the drawn structure does not need to solidify or generate support on its own. (B) As the tip moves, the granular gel locally fluidizes and then rapidly solidifies, leaving a drawn cylinder in its wake. The reversible transition allows the tip to traverse the same regions repeatedly. (C) The soft granular gel is a yield stress material, which elastically deforms at low shear strains and fluidizes at high strains. (D) Stress-strain measurements reveal a shear modulus of 64 Pa and a yield stress of 9 Pa for 0.2% (w/v) Carbopol gel. (E) The cross-sectional area of written features exhibits nearly ideal behavior over a wide range of tip speeds, v, and flow rates, Q. The trend line corresponds to the volume conserving relationship, .

Mentions: One of the most confounding problems in condensed matter physics is the transition between the fluid and disordered solid states (8, 15). Recently, a new complexity has been added to these studies by replacing the traditionally hard particles with soft microscale hydrogel particles (1, 10). Jamming transitions in soft granular gels are graceful and exhibit a smooth variation in material properties when crossing between the fluid and solid states. We leverage this intriguing behavior at the transition to write sophisticated multidimensional structures in a soft granular gel made from 7-μm-diameter hydrogel particles. This medium is fluidized under low shear stresses (1 to 200 Pa), permitting easy insertion and rapid motion of delicate needles deep within the bulk. The locally fluidized gel rapidly resolidifies in the wake to give a permanent and continuous medium that firmly holds the injected material in place (Fig. 1, fig. S1 to S5, and movies S1 and S2).


Writing in the granular gel medium.

Bhattacharjee T, Zehnder SM, Rowe KG, Jain S, Nixon RM, Sawyer WG, Angelini TE - Sci Adv (2015)

Granular gel as a 3D writing medium.(A) A microscale capillary tip sweeps out a complex pattern as material is injected into the granular gel medium. Complex objects can be generated because the drawn structure does not need to solidify or generate support on its own. (B) As the tip moves, the granular gel locally fluidizes and then rapidly solidifies, leaving a drawn cylinder in its wake. The reversible transition allows the tip to traverse the same regions repeatedly. (C) The soft granular gel is a yield stress material, which elastically deforms at low shear strains and fluidizes at high strains. (D) Stress-strain measurements reveal a shear modulus of 64 Pa and a yield stress of 9 Pa for 0.2% (w/v) Carbopol gel. (E) The cross-sectional area of written features exhibits nearly ideal behavior over a wide range of tip speeds, v, and flow rates, Q. The trend line corresponds to the volume conserving relationship, .
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643780&req=5

Figure 1: Granular gel as a 3D writing medium.(A) A microscale capillary tip sweeps out a complex pattern as material is injected into the granular gel medium. Complex objects can be generated because the drawn structure does not need to solidify or generate support on its own. (B) As the tip moves, the granular gel locally fluidizes and then rapidly solidifies, leaving a drawn cylinder in its wake. The reversible transition allows the tip to traverse the same regions repeatedly. (C) The soft granular gel is a yield stress material, which elastically deforms at low shear strains and fluidizes at high strains. (D) Stress-strain measurements reveal a shear modulus of 64 Pa and a yield stress of 9 Pa for 0.2% (w/v) Carbopol gel. (E) The cross-sectional area of written features exhibits nearly ideal behavior over a wide range of tip speeds, v, and flow rates, Q. The trend line corresponds to the volume conserving relationship, .
Mentions: One of the most confounding problems in condensed matter physics is the transition between the fluid and disordered solid states (8, 15). Recently, a new complexity has been added to these studies by replacing the traditionally hard particles with soft microscale hydrogel particles (1, 10). Jamming transitions in soft granular gels are graceful and exhibit a smooth variation in material properties when crossing between the fluid and solid states. We leverage this intriguing behavior at the transition to write sophisticated multidimensional structures in a soft granular gel made from 7-μm-diameter hydrogel particles. This medium is fluidized under low shear stresses (1 to 200 Pa), permitting easy insertion and rapid motion of delicate needles deep within the bulk. The locally fluidized gel rapidly resolidifies in the wake to give a permanent and continuous medium that firmly holds the injected material in place (Fig. 1, fig. S1 to S5, and movies S1 and S2).

Bottom Line: This physical approach to creating three-dimensional (3D) structures negates the effects of surface tension, gravity, and particle diffusion, allowing a limitless breadth of materials to be written.We crosslinked polymeric materials and removed them from the granular gel, whereas uncrosslinked particulate systems were left supported within the medium for long times.This approach can be immediately used in diverse areas, contributing to tissue engineering, flexible electronics, particle engineering, smart materials, and encapsulation technologies.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA.

ABSTRACT
Gels made from soft microscale particles smoothly transition between the fluid and solid states, making them an ideal medium in which to create macroscopic structures with microscopic precision. While tracing out spatial paths with an injection tip, the granular gel fluidizes at the point of injection and then rapidly solidifies, trapping injected material in place. This physical approach to creating three-dimensional (3D) structures negates the effects of surface tension, gravity, and particle diffusion, allowing a limitless breadth of materials to be written. With this method, we used silicones, hydrogels, colloids, and living cells to create complex large aspect ratio 3D objects, thin closed shells, and hierarchically branched tubular networks. We crosslinked polymeric materials and removed them from the granular gel, whereas uncrosslinked particulate systems were left supported within the medium for long times. This approach can be immediately used in diverse areas, contributing to tissue engineering, flexible electronics, particle engineering, smart materials, and encapsulation technologies.

No MeSH data available.


Related in: MedlinePlus