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Additive Manufacturing for Micro Medical Parts and Components

Avi Cohen VP of Healthcare and Education at XJet.
By Avi Cohen EVP Global Sales, Nanofabrica
A micro filter for medical applications created using Nanofabrica’s Tera 250 AM system. (All images provided by Nanofabrica)

AM equipment that makes small parts with micron sized features

There are a number of issues in the medical device sector that require OEMs to consistently review how they manufacture products.

First, there is a constant need to produce innovative, often geometrically complex parts repeatably and to exacting tolerances. Second, there is the drive to produce ever-smaller parts needed for minimally invasive procedures to enhance outcomes while minimizing recovery times. And third, there is a move away from mass production of multiple-millions of identical parts towards mass customization.

Because of these trends, using additive manufacturing (AM) is now a serious consideration for medical device OEMs. AM is agnostic to part complexity, requires no costly and time-consuming tooling, accommodates new design iterations without punitive time and cost implications, and promotes mass customization.

However, AM has until recently struggled with producing micro parts and components, and has also struggled with attaining the micron tolerances required in many medical devices. That is until the introduction of micro-AM technology by Nanofabrica, which through producing parts or direct rapid soft tooling (DRST) is now presenting a viable alternative process for medical applications.

Nanofabrica’s Tera 250 AM system achieves single micron resolution, and is targeted squarely at the medical, life sciences, optics, semi-conductor, micro-electronics, MEMS, and microfluidics sectors. These sectors demand accuracy and complexity, and until now their only choice has been disproportionately expensive or restrictive traditional manufacturing technologies.

What Drives Micro AM?

The Nanofabrica Tera 250 AM system achieves true single-micron resolution for both prototypes and mass-produced parts, enabled by a range of innovations.

Hardware. The Tera 250 AM system uses the digital light processor (DLP) engine, but crucially this is used with unique adaptive optics. In the Tera 250, once the image is projected through the Micro-DLP unit, the light then passes through an adaptive optics module, which electronically controls various critical optical working point parameters such as focus, tilt, and astigmatism.

The Micro-DLP unit is also placed on an optomechanical apparatus that facilitates real-time corrections of other working parameters such as location and accuracy in the X-Y plane. This apparatus also corrects for degrees of freedom such as wobbling to allow for better surface finish on parts.

The Tera 250 is able to build both small parts and large “macro” parts with intricate micro details, which can be manufactured at speed through what is called a “multi-resolution” strategy. This means that the areas where fine details are required are printed relatively slowly, but in the areas where the details aren’t so exacting, the part is printed at speeds 10-100 times faster.

Software. The Tera 250 uses algorithms to control and optimize the hardware during production. Within the Tera 250, feedback algorithms are used in a closed loop to increase accuracy and repeatability in production. Of particular importance, positioning errors are corrected using laser distance measurements. Another algorithm family is focused on customized file preparation, optimizing print angle, build plate orientation, and supports—all to ensure the most accurate, timely, and cost-effective part production.

Materials. Through R&D and in-house materials expertise, Nanofabrica developed its own proprietary materials (based on the most commonly used industry polymers such as ABS and PP). These materials enable ultra-high resolution in parts through modifications in polymerization radii, viscosity, surface tension, and spectral-optical penetration depth. Nanofabrica’s material R&D is also focused on the production of DRST robust enough to open up the possibility of medium-volume runs, which opens up potential for agile and cost-effective manufacturing.

With its hardware, software, and material innovations, the Tera 250 can be used in exacting medical micro manufacturing applications.

The Key—High Voxel Capacity

The name of the Nanofabrica micro AM technology is a nod to its most unique aspect; it produces micro products with micron resolutions. The AM system has 250 teravoxels in the build volume of the printer, hence the name—the Tera 250. Two hundred and 50 teravoxels means 250 trillion (250 times 1012) voxels. Nanofabrica’s technology applies a huge amount of data onto one part, which means precise, micron -level accuracy. Such capacity is only really required when dealing with with miniaturization and micro manufacturing.

The voxel capacity means that a large number of end-use parts can be accommodated in one build volume. For example, the Tera 250 can manufacture over 10,000 1 × 1 × 1 mm parts in a single build. True mass manufacture is now attainable through AM.

For medical device manufacturers, this is the goal when looking at AM as a production technology. It gives them the ability to mass produce AM parts without the need for hard tooling, and AM provides agility and geometric complexity that are impossible to achieve using traditional production techniques.

Using AM to Manufacture Medical Filters

The use of filters in medical applications is widespread since they protect patients from contaminants that may be deleterious. However, medical device manufacturers are constrained in what they can produce when using traditional molding processes when manufacturing devices such as filters for prefiltration applications, bioburden control, or sterilization.

First, the economics of molding and the cost of hard steel tooling means that it is suited to mass manufacturing, but is uneconomic when small to medium-sized runs are required. While the Tera 250 AM system can be effective for high-volume applications (multiple thousands of small parts and components fitting easily in the machine’s build envelope), the introduction of an AM solution for micro manufacturers also means that OEMs are able to reduce reliance on economies of scale, as the technology makes full production runs measured in thousands as inexpensive as producing one-offs.

In addition, it is not just the tooling cost that is often prohibitive. The time needed to fabricate and adjust steel tooling can add months to the product development process.

Also, design engineers are constrained when using traditional molding technologies. The required geometry of a filter may have to be compromised as it is impossible to create using traditional molding.

Nanofabrica's Tera 250 AM system delivers single-micron resolution which is especially important for medical devices.

All of these issues are exacerbated when manufacturing micro filters, or filters with micro features. Until the Tera 250 opened up the use of AM for producing micro parts, manufacturers relied on micro molding technologies, which required intricate, time-consuming and expensive micro tooling. The Tera 250 requires no tooling. Since it can produce highly complex parts, the Tera 250 opens up the possibility to produce parts with tight micro tolerances and features. It also enables the economical production of filters in small and medium-sized runs, and promotes mass customization. Using 3D printing for micro filters also delivers rapid design iterations, if required.

The micro filter shown is used in medical device applications, more specifically a drug delivery system. It measures 6 × 6 × 9 mm (X-Y-Z). Using the Tera 250 system, this micro filter was 3D printed as one part.

Conventional manufacturing processes require the production of three sub-systems to create the filter, and these sub-systems must be manually assembled post-production, adding time and cost.

This micro filter also displays the intricacy of the features that can be produced on the Tera 250, which enhance the part’s functionality as it optimizes filtration and flow. The filter also incorporates fine details and exacting and complex internal geometries, including 580 holes–each with a perfect 50-μm diameter.

Innovative Products Needed

The heat is on for medical device OEMs to maintain profitability despite pressure on prices, and as the decade progresses this will be achieved through the development of innovative products that fulfill the ever-more exacting requirements of end users. Demand will grow for versatile devices that embrace the potential for “smart” diagnostics and treatment presented by the proliferation of “big data,” as well as devices that provide cheap alternatives to traditionally used but expensive diagnostic and therapeutic devices.

The Tera 250 is useful for an array of medical device applications that until now have not been able to cost-effectively or efficiently fulfill design intent using traditional manufacturing processes. In addition, being agnostic to part complexity—and therefore allowing the manufacture of hollow structures, holes, complicated interior details, and atypical shapes—Nanofabrica’s micro AM technology is promoting innovation and is an enabling technology.

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