Consumables are a recurring cost that can make or break the market success of a Point of Care (POC) diagnostic device. As a result, device companies must pay close attention to the cost the market will bear and make decisions that keep consumable prices low. That means controlling materials and manufacturing costs and implementing an iterative product development process to minimize development costs. By paying close attention to these two elements, device manufacturers can lower consumable costs, mitigate delays, reduce development times, and more rapidly move their product into the marketplace.
Keep materials and manufacturing costs low
The design team must make many choices during development, and each decision is not made in isolation—choices often have downstream consequences. It’s important to consider the entire manufacturing workflow at each decision point.
1. Simplify the consumable design
POC device manufacturers should strive to make their consumable architecture as simple as possible by limiting the amount of functions performed on the consumable. If appropriate, always move a process from the consumable to the instrument.
Consumables are a recurring outlay for users, and complexity increases costs. Simplicity is also more sustainable. If a pump is on the consumable, it will be used once and thrown away; however, a pump on the instrument will last many cycles, reducing costs for end users.
2. Choose materials carefully
During development, you often have to choose between two or more materials. The first consideration is whether the material is compatible with the assay, but there are other factors as well. For example, polypropylene and polystyrene are both inexpensive materials. Polystyrene, however, is easier to mold with certain geometries, which can reduce manufacturing costs and produce a less expensive consumable.
Another potential issue is the coefficient of thermal expansion (CTE). When mixing and matching materials, CTEs must correspond. Materials that expand at different rates when heated can lead to problems down the road.
3. Reduce the number of parts
When possible, look for methods to reduce the number of parts in a consumable. For example, a cap to close a container can be formed in the same mold as the container. Also, you can avoid using an O-ring/elastomer on the cap by using an integrated flange in the cap to create the seal. Choosing the right materials early in the design could reduce this potential three-piece assembly to one piece. Each additional piece adds complexity and inflates manufacturing costs.
4. Choose the most appropriate manufacturing methods
The same care that goes into choosing consumable materials should apply to manufacturing processes. For example, there are many different bonding methods, including thermal, ultrasonic and laser welding. All three fundamentally melt pieces of plastic together.
Laser welding can be attractive because it’s a newer process that offers some advantages. Thermal welding is older, well-established, and a bit boring; however, thermal welders are significantly less expensive than laser instruments. Also, because thermal has been used for many years, the manufacturing process may be easier to develop. Choosing a newer, but less known, technology could add process development time. These choices should be driven by the consumable’s requirements, not by the newest technology.
5. Reduce labor costs
Labor is a major manufacturing expense. Each time a part is manually manipulated, costs increase. But this can be mitigated through design.
For example, when a reagent is dispensed in a collection of wells, ensure the wells are placed at the same orientation. If only some wells are filled and the device must be moved to fill other wells, that will increase costs.
Employ an iterative design approach
Problems will arise and trade-off decisions will need to be made – that is the nature of product development. However, using a proven framework of identifying high risk areas and employing an iterative design approach will mitigate risks early and inform a smarter decision-making process to keep development costs from spiraling out of control.
6. Address the highest risks first
You want to get your product to market as rapidly as possible. To do that, it’s important to identify and focus on key risks. Addressing every subsystem is far too time-consuming and may not be necessary. Instead, focus on pieces that are new, unique, or different. Adopt the 80/20 rule: 80 percent of the outcomes come from 20 percent of the causes.
7. Design the consumable architecture from subsystems
Divide the consumable into subsystems. Break down what the consumable has to do (its function) and define subsystems accordingly. After de-risking and developing independently, the subsystems are integrated to create a cohesive cartridge. This ultimately extends to instrument design—good design moves from the consumable subsystems to the integrated cartridge to the instrument. Each level informs the next.
8. Learn to pivot early
There are many choices that go into crafting a consumable. However, if a decision has gone awry, it’s important to correct that mistake as quickly as possible. Perhaps the consumable needs to be heated. Convection heating may seem appropriate at first, but don’t take that for granted—test early.
Results may show convection heating is generating problems, and conduction heating can work more efficiently. If that’s the case, make that decision to change rapidly, as it will have an enormous impact on the consumable’s geometry. Pivoting later could introduce unnecessary redesigns and delays, impacting the overall time to market.
9. Reducing unit costs vs. time to market
Identifying your critical design parameters early in the development process will make it easier to understand (and make) certain trade-offs. Time to market is critical for most device manufacturers, but some design decisions that may have long-term benefits can also extend development timelines. It’s important to understand the implications of design choices to the overall program and make the trade-off decisions most appropriate for the business.
For example, how will a filer be retained in a consumable? Let’s say it could be melted to the plastic (heat staked) or encapsulated (inserted during molding). Encapsulation might reduce consumable costs in the long run, but it could also increase development time. Understanding the critical success factors for the overall product development program can make these design trade-off decisions easier.
10. Consumable before instrument
Having the consumable design lead the instrument design is critical as the consumable architecture will change in early development. Trying to design an instrument to interface with it would be like trying to hit a moving target. Starting detailed instrument design after the consumable architecture has been locked can prevent instrument iterations and reduce development costs.
For example, consumable valve design and actuation force may create an incompatibility between the consumable and the instrument. If it is determined that more force is needed and you’ve already invested quite a bit into injection molding, redesigning the mold tool would be costly and cause delays. It would be better to change the force provided by the instrument as that rework is typically faster and cheaper.
Another issue can be solving problems during the testing process. If the instrument and consumable are being tested in unison and fail, it’s difficult to know which piece is causing the problem. Evaluating their functionality independently will reduce these instances, but even this may pose a challenge for consumables. POC devices typically have a relatively small manufacturing run, so a 5 percent failure rate could be worked around; however, if millions of consumables are produced, 5 percent is a disaster. In addition, some consumable failures may not be realized until larger quantities have been produced.
11. Consider the experience of the end user
Many products fail due to poor usability. Insights achieved from early research into user needs and feedback through formative testing will inform consumable design decisions, surface concerns early, and head off potential problems while they are less expensive to mitigate.
While chemists and other bench scientists may design the original assay, medical assistants, nurses, and possibly patients will be the ones managing the POC test. The final product must be designed with these users in mind. For example, something that may be as simple as loading a sample into the consumable can benefit from user testing. Questions like how much to load, can the user over or underfill, etc. is something that can only be answered by observing real users.
Adopting an iterative process, in which inexpensive prototypes are tested and retested with users, can ensure the device reaches a high standard for usability. Different disciplines should work together as the design comes together – consumable engineers, instrument engineers, industrial designers, human factors engineers, usability engineers, digital designers, embedded software developers, electrical engineers, and molecular scientists may all play a role in bringing a low-cost consumable to fruition.
Make the right choices
Developing a Point of Care diagnostic device requires making trade-offs, and each one has different ramifications. Some can reduce instrument or consumable costs but may increase time to market. Consumable development teams must understand how each component, the materials being used, and the manufacturing process, all impact the big picture. That’s the best way to efficiently make informed decisions that reduce costs and keep product development on track.
Ultimately, keeping the consumable cost low offers more flexibility on price and improves the potential for market success and profitability.
Guide: Best Practices for Point of Care Product Development
For more strategies to decrease costs, download our Best Practices for POC Product Development Guide.
Darryl is Associate Principal Mechanical Engineer at Invetech’s San Diego office. He leads a cross-functional team of engineers on product development projects for our medical device and life science clients.