3D printing is commonly seen as a method that entails laying down layer after layer of molten plastic, which solidifies as a self-supporting structure is constructed. However, many soft materials do not melt and re-solidify in the same manner that the plastic filament used in 3D printers does. With soft materials like silicone, users only get one shot – they must be printed in a liquid condition and then irreversibly solidified.
How can you create a sophisticated 3D structure out of a liquid without creating a puddle or a sagging blob?
For this objective, researchers devised a comprehensive approach known as embedded 3D printing. The “ink” is deposited inside a bath of a second supporting substance designed to flow around the printing nozzle and retain the ink just after the nozzle moves away in this approach. This enables users to make complicated structures out of liquids by trapping them in three-dimensional space until the printed object is solidified. Embedded 3D printing has proven useful for constructing a wide range of soft materials, including hydrogels, microparticles, and even living cells.
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Unfortunately, printing with silicone has proven difficult. While most support materials are water-based, liquid silicone is an oil. Oil and water have a high interfacial tension, which is what causes oil droplets to take on circular forms in water. This force causes 3D-printed silicone structures to distort, even when supported by a support medium.
Worse, as they are printed, these interfacial forces cause small-diameter silicone features to shatter into droplets. A lot of research has gone into developing silicone materials that can be printed without support, but these drastic changes also change the attributes that consumers care about, such as how soft and elastic the silicone is.
AMULIT 3D Printing Silicone: Breaking the Interfacial Tension Barrier
As researchers at the intersection of soft matter physics, mechanical engineering, and materials science, we decided to solve the problem of interfacial tension by designing a silicone oil support material.
We reasoned that most silicone inks would be chemically similar to our silicone support material, reducing interfacial tension significantly, but also different enough to stay distinct when combined for 3D printing. We developed several possible support materials before deciding on a dense emulsion of silicone oil and water. Consider it like crystal transparent mayonnaise, formed from packed microdroplets of water in a silicone oil continuity. AMULIT stands for additive manufacturing at ultra-low interfacial tension.
We were able to print off-the-shelf silicone at high resolution using our AMULIT support medium, making features as small as 8 micrometers (approximately 0.0003 inches) in diameter. The printed structures are just as elastic and robust as their molded counterparts.
We were able to 3D-print accurate models of a patient’s cerebral blood arteries based on a 3D scan, as well as a functioning heart valve model based on average human anatomy, thanks to these capabilities.
Transforming Healthcare with 3D-Printed Patient-Specific Mimics of Physiological Structures
Silicone is used in a wide range of products, from daily consumer goods like cookware and toys to cutting-edge technologies in the electronics, aerospace, and healthcare industries.
Typically, silicone items are created by pouring or injecting liquid silicone into a mold and extracting the cast once it has solidified. Because of the cost and difficulty of producing high-precision molds, producers are limited to goods with a few preset sizes, forms, and patterns. Removing delicate silicone structures from molds without causing damage is another hurdle, and manufacturing faults rise when molding highly sophisticated structures.
Addressing these obstacles could pave the way for the development of advanced silicone-based technologies in the healthcare business, such as tailored implants or patient-specific mimics of physiological structures, which could transform care.
Source: Medindia
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