Timing truly is central to business success.
 
Microsoft, for example, could very well have been the world’s first trillion-dollar company had the public warmed to its tablet at the millennium’s dawning. Similarly, the world was not quite ready to embrace the future when Bell Labs unveiled its Picturephone in 1964 (imagine how different life would be today had it become commonplace back then).
 
Surprisingly, biotechnology firm Vaxxas hasn’t encountered that same dead end despite its invention being a bit ahead of its own time. The privately-held company is developing needle-free vaccination technology originally hatched by the Australian Institute of Bioengineering & Nanotechnology at The University of Queensland.
 
The technology uses a proprietary high-density micro-projection array patch (HD-MAP) to streamline and improve vaccine delivery. The postage stamp-sized silicon patch contains tens of thousands of projections 200-300 microns in length that release vaccine antigens directly to immune cells sitting just below the skin’s surface.
 
Preclinical studies have shown the Nanopatch to be considerably more effective than conventional vaccine delivery systems, with as little as 1/100th of its dose eliciting the same immune response as a “full” portion through intramuscular injection. Moreover, Nanopatch’s dry-coating technology eliminates the need for vaccine refrigeration during storage and transportation, thereby eliminating the resource burden of maintaining a cold chain.
 
“Based on our results, we believe that Vaxxas’ HD-MAP could offer a compelling solution that importantly could use less vaccine and potentially could be readily distributed without refrigeration for self-administration,” David A. Muller, Advance Queensland Industry Research Fellow, School of Chemistry and Molecular Biosciences, The University of Queensland, said last June. “This combination could make the HD-MAP extremely well suited to support the massive need for global population vaccination and indeed, we believe that HD-MAP offers a superior alternative to conventional needle-and-syringe.”
 
That superiority lies in the microscopic projections responsible for delivering vaccines. Those projections likely were created through micromolding, a highly specialized manufacturing process that produces extremely small, high-precision thermoplastic components with micron tolerances. This technique has become integral to medical device manufacturing of late as devices continue to shrink in size and scale. 
 
MPO’s feature “Big Shots” details the trends and market forces driving micromolding in the medical device industry. Donna Bibber, CEO, and Brent Hahn, sales/marketing director at Isometric Micro Molding Inc., were among the more than one dozen experts interviewed for the feature. Their full input is provided in the following Q&A:
 
Michael Barbella: What are the latest trends in micromolding technology and services?
Donna Bibber and Brent Hahn: CT scanned component and assembly data, full factorials of combinations of number of cavities, lots, material lot to lot variation, and building these assemblies with all of these combinations and CT scanning these results in STL files of utmost importance to clinical trial data, visual recognition of variation, and innovation for new and improved products and processes of the future.
 
Barbella: What are customers demanding or expecting of their micromolded products and have these demands/expectations changed in recent years?
Bibber and Hahn: The ability to mold smaller and smaller parts in overall size as well as micro features and/or tight tolerances on 5-inch or smaller parts. Furthermore, Industry 4.0 and ISO 21CFR Part 11 compliance is trending for micromolding technology due to pharmaceutical and drug delivery data and process control. Data, changes to process, and analysis of automated, collected data will contribute to next-generation products. 

Barbella: How have advances in materials impacted micromolding technology?
Bibber and Hahn: Newly developed polymer formulations are coming to market with ISO 10993 ratings and melt flow properties needed to fill ultra-thin and high aspect ratio injection molded components. Materials such as Pebax and Arnitel nylon copolymers

have strong tensile and other physical properties, even down to 25-micron thicknesses. With smaller and smaller spaces in catheters, endoscopes, and robotic surgery instruments, these materials are key drivers to successful miniaturized device sizes and strength. Other commonly used micromolding polymers are PEEK, polycarbonate, polysulfone, polyurethane, bioresorbables, and liquid crystalline polymers, to name a few. 
Some polymers require risk mitigation strategies that Isometric employs prior to completing mold designs. Micro tensile bar molding as shown in the figure to the right has a range of 0.001” -0.008” thick bars with varying gate styles (edge and pin) and varying gate diameters from 0.006” to 0.013”. These inputs mimic the gate diameter/type and wall thicknesses of the parts we plan to mold and generate the following outputs that are used by in-house mold designers and process engineers to flush out risks very early in the project phase. These outputs are: 

• Actual polymer shrink vs. estimated
• Gate style effectiveness to fill
• Gate vestige with actual gate size/material
• Thin wall molding test prior to mold building
• Gate shear of Pin gate vs. Edge gate and material property impact 

Molding thermoplastic urethane (TPU) for example, has a very wide range of shrink. If not calculated properly, molded parts sizes can be much smaller or larger than designed and cause molds to be rebuilt, pushing timelines out significantly. Running micro tensile bars in the thickness and gate diameter pre-planned for the actual molded part mitigates this costly error and feeds the necessary inputs into a geometrically correct and robust mold design. 
 
Barbella: Please discuss the challenges and complexities involved in micromolding tooling design. How can these challenges be overcome?
Bibber and Hahn: Since the mold is the enabler to micro molding, this is an extremely important component of a PFMEA, which Isometric developed called Microns Matter®. As shown in the figure to the left, the Microns Matter® method breaks down the tolerances such that our mold is built to 20 percent or less of the tolerance to leave the remaining 80 percent of the tolerance to be taken up with molding process, gage R&R, material lot to lot variation, and material drying. The reason for a robust mold design/fabrication plan is two-fold.  
First, if the part tolerances are 16 microns and the Cpk is 1.33, the mold needs to be built to 4-micron tolerance to be capable. Missing this important step in the risk mitigation plan results in tolerance stack-up errors later in the project where costs are exacerbated and cannot be afforded by medial and drug delivery device OEMs. Second, the mold maintenance, dimensional monitoring and control are key to holding the Cpk over the full depreciation schedule of the mold. When this maintenance is completed by the very same journey mold makers that fabricated it, this addresses again the overall Cpk and reduces stack-up errors. 
As Vice President of Operations Wayne Shakal noted in an October 2020 micromolding feature in MPO:
A tool designer must have a clear understanding of what is possible with micro-machining in order to properly design a mold that is manufacturable. For example, it is not uncommon for us to see part features that are only a few thousandths in size. The designer must know what machining method will be optimal to put the feature into the tool steel and whether or not there are limitations with cutter reach, cutter diameter, electrode overburn, accuracy requirements, etc. Often these limitations require separating this tool steel out from the rest of the cavity and manufacturing it as a stand-alone piece. Knowing that this is required adds complexity in fitting the componentry together without giving up positional accuracy of a micron. Also, due to the extreme injection speeds and extremely small fill volumes, the molds must be able to vent properly. This is important in any mold, but it is exceedingly more difficult to achieve in many micro applications. The difference from failure and success is once again at the micron level.   A 1–2-micron difference in vent depth can be the difference between a part that will not fill and a part that has too much flash. It takes painstaking attention to detail, beginning at design and carried all the way through for these applications to be a success.
 
Barbella: Design for Manufacturability is critically important in micromolding. How is this different than conventional DfM?
Bibber and Hahn: As shown in Microns Matter®, DfM is critical to reduce error in micromolded components, and even more critical in reducing stack-up errors in assemblies. Isometric Micro Molding has designed and built micro automation systems in-house for 14 years. It has therefore become evident during this experience, that scalability of 32 cavities of one part, 16 cavities of another, 16 cavities of yet another, and eight cavities of another can cause stack-up errors in automated assemblies. Addressing these stack-up risks start as early as the project quote. Reviewing component tolerances with Microns Matter® mentality addresses the full factorial of molding, cavity to cavity, process DOE extremes, and material lot to lot variation. Using in-house CT scanning throughout this process provides visual STL color deviation plots such as the one in the figure at right Cavity 6 and 7 are nearly short shots where others are full. Within 15 minutes of molding these, the error has been identified with a full first article view of all cavities and the process variables that contribute to critical-to-function specifications. Dialing this in quickly using in-house CT scanning data leads to faster and more accurate component and assembly DfM, scalability, and economically feasible automated assemblies.
 
Barbella: Are machine learning and AI playing a role in medical device micromolding? If so, how?
Bibber and Hahn: Yes, there continue to be machine learning and AI advancements with the molding presses, third party add ons, and automation. We have incorporated these advancements into algorithms and control functionality that we create, allowing us to support Industry 4.0 automation data for OEMs on their next-generation platforms.
 
Barbella: Is there a limit to how small a micro molded part can be?  
Bibber and Hahn: The short answer is yes, and it is dependent on many variables such as material selection, gate size and location, and mold design robustness. Having said that, our smallest molded part was over 1,000 parts per plastic pellet. Parts that are hundreds of parts to a single pellet are moldable, but there’s a limit as to the number of cavities that can be pellet split and still be moldable in scale. This is known on a case-by-case basis; however, generally speaking this extreme is rarely more than four cavities while other micro molded parts can be 16, 32, or even 64 cavities. 
 
Barbella: What medtech speciality (cardiology, wearables, orthopedics, etc.) presents the greatest challenge in producing micro molded parts and why? Which present the greatest opportunity?
Bibber: Every medtech specialty and application has its own challenge so I’ll speak in generalities. 
Cardiology: Interventional catheters require many moving parts in small and long spaces. The challenges here are stack-up tolerances, automating and mimicking traditionally hand-loaded operations, handling guidewires, creating extremely clean and accurate catheter tips. These challenges all require accurate tooling, robust automated assembly design, and a correspondingly detailed process map and PFMEA to validate. Isometric has built automation systems that handle 0.001” diameter guidewires with 5 nanoliters of dispense volumes. Just as the mold is the enabler to the molding, the positional accuracy of the automated fixtures is the enabler to micro device automation. The devil is in the details for sure.
Wearables: Micro molded components and assemblies for wearables relies heavily on the accuracy of the electronics and whether those electronics can be potted or encapsulated without damaging the electronics. Special handling, dispensing, and visualization through highly magnified fixtures and high-speed cameras address these challenges during setup and validation to achieve the necessary mix of electronics, polymers, guidewires, and sensors in the wearable. 
Hahn: Orthopedic applications continue to get smaller and typically incorporate PEEK or bioresorbable resins in their long-term implants. The ability to mold flash-free parts to prevent flash from breaking off in the body while molding very high temperatures and pressure is a skill set developed over many years. In addition, new orthopedic applications are getting longer and thinner, creating long flow aspect ratios in high viscosity resins. Isometric has been on the forefront of mold design, process control, and air and gas venting of high aspect ratio molding and thin wall molding in materials like PEEK.
 
Barbella: What regulatory requirements/changes have impacted medtech micromolding and how?
Bibber and Hahn: The impact a molder has on a medical OEM’s submission has increased. Isometric supports our customers’ filings by creating a plan for each component or assembly. There are many aspects, but the most impactful has been incorporating CT scan data into the OEM’s submissions.
 
Barbella: How might the medtech micromolding industry evolve over the next five years?
Bibber and Hahn: Molding, 3D micro printing, material development, and miniaturized devices are a high-growth niche business. It will be important for micromolders and automated micro assemblers like Isometric to continue to focus on moving the decimal points to the right in terms of part size, tolerance, wall thickness, and feature size.  
Retaining skilled talent will continue to be important to innovation. Isometric has less than 1 percent employee turnover in the 31-year history of the company. The basis of Isometric’s core values will continue to be important factors in our ability to retain these skill sets and employees to ensure future success. 
Adding surface finishes, incorporating biomimicry of hydrophobic and hydrophilic surfaces, and other surface treatments such as plasma and corona treatments will enhance the physical bond strength and performance of miniaturized devices of the future. It’s common for technical and engineering-focused companies to get side tracked on “the shiny stuff”; however, to truly grow, partnerships with key customers and fulfilling their needs is the heart of what provides continued growth and prosperity.