Here’s why medical device creators need to design wearables and microfluidics manufacturability and scalability to achieve the optimal performance patients and providers rely on.

David Franta and Matt Berdahl, 3M Medical Materials and Technologies

Point-of-care, microfluidic and wearable medical devices play a key role in the enablement of positive care outcomes and help simplify care management — changing patients’ quality of life for the better. In order for these devices to achieve peak performance and produce accurate measurements and readings users can rely on, design engineers need to particularly focus on three elements of the development process. Thoughtfully considering materials, manufacturing processes and scalability according to the application are critical steps in bringing the device to life.

From prototype to product, materials matter

In order to demonstrate the ability to function reliably while being mass produced, it’s important to use the same materials in the prototype that will also be used in the end product. If you use different materials for the prototype and finished device, it could yield unexpected results at various phases in development, throwing a wrench in the overall plan.

Some of the most common materials used in device design include glass, PMMA, polycarbonate, polystyrene, COP or COC, PDMS, metal, flexible web and paper. Glass typically has the best chemical resistance, but it’s fragile and is not the easiest material to work with, if the device will be mass produced. Considering all of the tradeoffs based on your product and its unique application is crucial. For microfluidic devices, polymeric films and sheets are popular because they enable a scalable manufacturing process.

It is also important to consider compatibility and temperature conditions. If the polymer materials used in your device are not compatible with each other, it can affect diagnostic integrity. In addition, note the polymer material’s thermal-transition properties, if the device will be exposed to extreme temperatures or hostile environments during storage. Hostile environments, pressures or chemical reactivity and other harsh conditions may require resilient and versatile materials.

Plan ahead for manufacturing

While it may sound obvious, manufacturing processes influence other design decisions you will have to make before the device gets to the production floor. There are a variety of manufacturing methods used to produce medical devices. While some use chemicals, such as strong acids, others require thermal operations to fabricate devices. These processes can have a huge impact on material properties. Some common methods include etching, lasering, casting, molding, roll to roll hot embossing, and planar processing. Below is a short summary of each process to keep in mind before selecting one for your project.

Small to large volume processes

• Roll to roll processing: This method is compatible with an array of different materials. During this process each material layer is cut individually. First, the device is designed as a CAD file, then the geometry is cut, the inner portion is cleaned, and the layers of the device are bonded together. Keep in mind, this process’ accuracy is dependent upon your chosen cutting method, materials, layer registration, and layer thickness.

Large volume processes

• Hot embossing: This is a process commonly used for replicating products since it is typically easy to tool-up for and execute. This is a preferred process for replicating microstructures, as the tooling is fairly simple.
• Injection molding: Molding is often used for microreplication and microscale thermoplastic replication. While it may have faster cycle times, it requires more expensive, intricate tooling, and larger investments in order to execute effectively.
• Other planar processing: Other types of planar processing can be used on silicon or glass materials. Processes may involve chemical etching, dry etching and powder blasting.

Others processes

Casting (small volume): Casting is the process of creating a device by pouring (casting) PDMS into a mold of the product.

Laser (small to medium volumes): This process utilizes noncontact micromachining systems. Laser systems have the ability to be reprogrammed to produce varied patterns, which makes them ideal for the design and development phase of the microfluidic biosensor.

Powder blasting: Powder blasting creates fluidic channels by mechanically removing part of the structure’s material with a particle jet machine.

Etching: There are several types of etching. Dry etching can create deep, high density, high aspect ratio structures in glass and silicon substrates. Similarly, wet etching can create useful features but uses chemicals like hydrofluoric acid to create channel structures in glass and silicon substrates. Feature fidelity and edge sharpness should be evaluated when using etching processes.

Make it scalable from the beginning

Scalability of the prototype impacts material selection, end-user, environment, as well as manufacturing process decisions, which is why it needs to be thought about early on in device development.

There are three main stages that comprise the scaling process. During the first stage of scaling, materials and individual components are joined to create a working assay. Once this step is complete, the product’s robustness, including sensitivity, selectivity, specificity and reproducibility, is evaluated and compared to laboratory performance. This evaluation will inform whether design improvements are necessary to mitigate any design issues or manufacturing variations that arise. The second stage of scaling may use higher-speed replication processes to produce the desired batch/volume of devices, while still meeting the critical design parameters identified. In the final stage of scaling, you should be able to produce the volume of devices needed to meet your forecasted yearly-use volumes – perhaps 10,000 devices or more in the span of a few months. Depending on the production goals you set for your product, a clear manufacturing path needs to be laid out before beginning production, in order to successfully achieve the desired target volumes.

Since mass-manufacturing medical devices is an iterative and multi-step process, making thoughtful decisions on material selection, manufacturing techniques, scalability and development parameters will help ensure device development and production goes smoothly. If you decide change is necessary later in the design and development phases, you will likely run into setbacks, such as added costs and time delays. Visit FindMyAdhesive.com and answer a series of project-specific questions to get started down the right path. Be sure to engage your material supplier early on to solicit recommendations – and pay attention to these considerations to ensure your solution is scalable and successful— from concept through commercialization.

For more tips, read 3M’s “Guide to Manufacturing Microfluidic Device Key Components.”

David Franta is microfluidics global business manager at 3M Medical Materials and Technologies. Franta received a BS in material science from the University of Minnesota, Twin Cities. He has more than 25 years of experience at 3M in product and process development, business management, strategic product platform creation and Lean Six Sigma operations. His experience has involved new technology creation in biomedical sensors, biotechnology solutions and medical adhesives. 

Matthew Berdahl is global marketing manager for pressure-sensitive adhesives and tapes at 3M Medical Materials and Technologies.  Berdahl received his BA in operations management as well as his MBA from the University of St. Thomas in St. Paul, Minn.  Matt has 23 years of experience at 3M in a variety of roles including the supply chain, procurement, Lean Six Sigma, sales, marketing and business operations.  His business experience has involved tapes and adhesives that are used in the industrial, consumer, transportation safety and medical markets.  

The opinions expressed in this blog post are the author’s only and do not necessarily reflect those of Medical Design and Outsourcing or its employees.