What, exactly, are design controls?

Why are they important in the world of medical devices?

Today we’re talking with Grace, a mechanical engineer, about her experience with design controls and how to implement them without stalling design progress.

 

Julia

So Grace, what’s your role at Blur and what experience do you have with design controls?

Grace

I’m an R&D engineer here at Blur, so I work primarily on mechanical design. Throughout my time here I’ve worked on several projects that involve design controls, from drafting requirements and user needs to creating design control matrices and then that dictates V&V. Also, executing V&V protocols and writing reports.

Britt

So what are design controls and why are they important?

Grace

Design controls are a road map for medical device development, and it takes a concept and brings it to a final design. It really starts from the beginning of a design and evolves with a device.

Julia

What’s one misconception people have when it comes to design controls?

Grace

That you can start after you’ve already designed your device. I know that Dustin touched on in a previous episode that a pitfall is you’ve only concentrated on the device and then you have to go back and come up with your user needs, product requirements, and the whole process. You could miss something because you don’t have all of those requirements outlined. You’ve created a device where there’s no way to calibrate it, or there’s a part in your device that is going to need regular maintenance and it’s really difficult to access so from a service standpoint you’ve missed something and you’ll have to go back and change things. 

I think it’s best to start after you have some sort of concept, or maybe the client has come to you with some sort of rudimentary prototype. That helps you identify here’s my user needs, here’s my product requirements, I have a handle on that. If you move forward and iterate on the prototype without design controls, you’ll probably end up with something close to the final device but have to go back and generate all of the documentation.

Julia

How do you balance the paperwork side of design controls, getting it done and not letting it all live in your head, but as a mechanical engineer getting the actual design done. Working on it, testing it, and evaluating it. I think maybe there’s a perception that design controls are taking away progress of the device design.

Grace

It has to be hand in hand, where you’re making progress on both sides, not just focusing on the design and you’ll do documentation later. It really impacts the timeline when you have to go back and do all of the documentation when you weren’t trying to keep up with it throughout the design.

Britt

Or even adapting. We had a client recently that came and they designed a device to fit in your hand, and it does that beautifully. Then when they actually put it in the field to test it out, the nurses were actually putting it in their coat pockets because it’s a small device. Now when the nurse bends over, it will fall out because it’s kind of slippery and it’s meant to be a remote control type feel.

We’re helping them come up with a more durable solution now that we understand that they’re not going to hold this and walk around the hospital. They’re going to put it in their scrubs pocket or they’re going to put it on a cart and their cart is also slippery. So then just working with clients to adapt their products and then think through the next risk associated with that. That’s some of what we have to do.

Julia

What does the process look like at Bur for implementing design controls?

Grace

Well, we start by generating a development plan. We work with a client and define the purpose of the device, provide a basic overview of what we want to create, and we break up the design into phases so we have a more manageable timeline. It’s an easier way to manage budget as well. 

Then identify any regulatory standards you want to comply with, that’s really important. Then working with clients to outline the needs of the user, and then after that’s defined including engineers to create product requirements. Think internal hardware, like pumps and sensors, anything that’s important to create a functional device. 

Once you have your user needs and product requirements laid out, you’re going to move on to risk assessments where we’ll identify potential hazards or harms associated with user operation of the device. So, how are you preventing unnecessary exposure to laser or electric shock which is very important to demonstrate to the FDA? 

Once all of those inputs are defined, we’ll go into design and development. Now I’ve got a strong foundation that I can create my design, making sure I’m taking into account the user needs and the product requirements. 

Julia

Having those requirements actually takes some of the fatigue out of making decisions; when you give yourself those guardrails, you can more easily say, “Oh, do we need an app or do we not need an app? Is the user population actually going to use this?” It takes the fatigue out of it, makes it easier to make decisions, and that also helps the timeline.

Grace

I think it helps to involve the whole team, too, so the teams aren’t siloed. You don’t want to say your firmware needs to do this, your mechanical engineer needs to do this, your electrical engineer needs to do this. Once you have an overall idea of how you need your device to work, I think it helps cross-functional teams communicate better so you can move faster in design and development.  

Throughout the process you’re doing design reviews, so have I checked all of the boxes for my requirements? You may change things from your design review. After that you’re going to generate your design control matrix, which is the big document that links all of the user and clinical needs and product requirements and risk to the design characteristics of your device. Say the user needs to use the device in a wet environment, now I need to create a sealed enclosure with a gasket to prevent water ingress. 

From that big design control matrix document, that’s how you generate all of your verification and validation protocols. This is really the final step in your design, you’ve made it, you’re almost there to submit regulatory approval. You have to test your device and make sure you’ve met all of those outputs. 

Like I said before, if you’re trying to create a device that’s going to be used in a wet environment then you would send the device off to a third-party ingress testing. They’re going to test your device, open it up and make sure there isn’t any water inside. 

Julia

How does Blur’s design control system adapt to different levels of technology with different levels of risk?

Grace

Taking risk into account from the beginning of the project so you’re not designing blind to any harms to the user or the clinical environment. So, having a risk management plan to outline what steps you’re going to take throughout the design controls process to identify and mitigate risk and determine who’s responsible for what tasks along the way. Then doing a risk analysis where you’re breaking down every risk associated with the device or process by identifying the intended use or misuse and then the hazards or hazardous situations, and assigning a probability of occurrence. What’s the likelihood of  a fire hazard or electric shock to the user? Taking all of that and putting controls in place to mitigate the risk. Say for a fire hazard, I know I need a fire-rated enclosure. For electric shock, I know I need to design the housings to prevent the user from being exposed to the electronics if they drop the device, things of that nature.

After device V&V, we can always go back and see if there is any residual risk by completing a benefit-risk analysis and maybe modify the intended use if necessary. Throughout the design process you’re conducting risk reviews, writing reports, and ensuring the final design is a low-risk device that is safe for the intended use.

Julia

Having seen a risk document or two, they can be super detailed. How do you know what to put in there, how do you determine that?

Grace

That’s a good question, I think it takes a team to fill out a risk analysis. You’re going to have to lean on the client because they’re going to know more about the environment it’s being used in. 

Also, not just having one person do the risk analysis is very important; one person is only going to think about a subset of the risk, and maybe they’re only going to think about the risk from the electrical standpoint or from the mechanical design standpoint. Having as many eyes as you can look at the risk analysis is how you get to a good document that everyone is happy with, including the FDA.

Julia

We’ve talked a lot about mechanical design and device development on the physical side of things. Can you tell me a little bit about how software and firmware is handled within our design controls?

Grace

Our approach is to separate the software and firmware from the hardware. Software and firmware gets its own development from the outset of the design. 

Once the user needs and product requirements have been established and you’ve created your software and firmware, you generate a product specifications document. You basically describe the functionality of the software and firmware to show how you’ve written it and accomplished those functions. 

Obviously we’re going to have separate V&V protocols to test against the inputs and show that you’ve met your requirements. All of the software and firmware releases are documented; every time you release software and firmware on the device it’s a heavily documented process. Everything is under controls. 

Julia

If you were to sum up design controls and the importance of it in a couple of sentences, tl;dr, what would you say?

Grace

Design controls are important for knowing how the device should be designed and what features you need to include to mitigate risk. 

We talked about having water ingress protection, or being able to pass a drop test to prevent electric shock, or having a fire-rated enclosure so there’s no fire hazard to the user or use environment. 

Ensuring that you’ve included everything that a user needs to successfully use your device and ultimately benefit from the use of your device, because that’s what medical device development is all about.