How a 3D Printer Makes Flexible Medical Devices with Two Liquids

This patent describes a specialized 3D printing system that precisely mixes and deposits two liquid silicone parts to create flexible, solid medical devices like prosthetics, using a rotating and translating base and a special nozzle that prevents drips.

What it covers

This system is designed for "additive manufacturing" (3D printing) of medical devices using liquid silicone. It uses two separate reservoirs, one for "part A" and one for "part B" of an uncured liquid silicone material (Claim 1). These two parts are kept separate until they reach a "dynamic mixer" inside the "deposition apparatus" (the print head), where an "impeller" blends them together just before they exit the "nozzle" (Claim 1). The mixed silicone is then deposited onto a "cylindrical or conical mandrel" (a rotating mold) which can both "rotate" and "translate" (move along its axis) (Claim 1). The print head also moves to build up the desired shape (Claim 1). A key feature is a "pneumatic suck-back valve" that pulls back the silicone from the nozzle after each deposit, ensuring "clean breaks between distinct filaments" (Claim 1). For example, it could precisely build up layers of a custom prosthetic liner directly onto a rotating mold.

What it doesn't cover

• —Does not cover 3D printing systems that use non-silicone materials or materials that are not two-part liquid curable systems.
• —Does not cover systems that mix the two silicone parts before they enter the dynamic mixer within the deposition apparatus, as the patent specifies a "combined, but unblended, flow" before mixing.
• —Does not cover deposition onto flat or irregularly shaped substrates that are not cylindrical or conical mandrels.
• —Does not cover systems that lack a pneumatic suck-back valve to prevent dripping and ensure clean filament breaks.
• —Does not cover systems where the mandrel does not rotate and translate, or where the deposition apparatus does not translate.

The clever bit

The novelty lies in the combination of a dynamic mixer that precisely blends two liquid silicone components just before deposition, coupled with a pneumatic suck-back valve that actively retracts material from the nozzle. This ensures consistent material properties and prevents messy drips, allowing for intricate and high-quality elastomeric structures.

Why it matters

This patent is important for creating custom medical devices that need to be flexible and precisely shaped, like prosthetic sockets or orthotics. By allowing precise control over the mixing and deposition of elastomeric materials, it enables the creation of devices tailored to individual patient needs, which can improve comfort and function. The ability to form clean breaks between deposited material segments is critical for high-quality, consistent structures.

Real-world examples

• 1.Custom prosthetic liners
• 2.Orthotic inserts
• 3.Soft robotic components
• 4.Flexible medical implants
• 5.Custom seals and gaskets made of silicone