Design & Development

“Your Design Input Specification is important beyond regulatory compliance”

An insufficient or incomplete design input specification (DIS) can lead to a host of problems and create a big mess.


A design input specification is a design control requirement for medical devices seeking regulatory approval.  According to the FDA, your DIS must be testable, measurable, unambiguous, and traceable.


Ambiguity leads to poor design inputs.  Inputs that are open to more than one interpretation will be very complicated to measure.

Early on, without a strong DIS, it is difficult to tell if your prototype is good or bad.  90% of prototypes fail their first submission. Will yours?


The misgivings from a poor DIS can also present as issues much later in your product lifecycle.  What if your device fails in the market?

You can miss your target or attempt to sell something that no one wants to buy; even if your device is highly useful and beneficial.  Without proper sales, you would be trapped and stressed.

It would be back to the drawing board.  You may even have to redo your entire design.  How would you trace back to what you missed?


Even worse, not having a proper DIS can lead to complaints from customers.  Without taking the time to do proper research and testing, the device may end up not being in tune with what the customer wants.

Worst case, there is the potential to harm someone, and having your product recalled.

Your reputation will be damaged.



Anxious about the state of your design input specification?

As you can see,

Having a proper design input specification is very important.  Your DIS is like a master plan, complete with all the checkpoints you must make.

Most of the important DIS come from what the customer or patient needs.

To generate these inputs, you must go out and gather them.  Create models of your device and have the actual target users use them – during DIS development.

Generating DIS is an active process and overlaps with other stages of product development.


You must also pay attention to perception.



Imagine developing a Design Input Specification to define the term “portable”.

Simply perceiving portable as “lightweight” is not enough.  To be portable, you must also consider shape and size.

Also, your understanding of “lightweight” may not be the target user’s perception of “lightweight”.  Imagine your device is for someone wheelchair bound, what is lightweight to them?

With a robust DIS, the resulting design outputs will be measurable and testable; suitable to demonstrate that you’ve satisfied the user’s definition of portable.


Don’t guess what might be right, discover what IS right.

With a well-formed DIS, you will stay on track with what your vision REALLY is.




Assumptions are dangerous.  Whether they are our own or others’, they can be misleading.  For example, you cannot assume you know what a customer wants or, like previously, what lightweight is.

Times change and with it come new perspectives and methods.  Unfortunately, some assumptions can take too long to follow suit.  What was attractive 10 years ago may not be so today.

For an example of this concept, surgical mesh was once assumed to be a simple 20-minute procedure; a quick fix for conditions like hernias or urinary issues.  The designers and even doctors assumed it would work.

However today, it has come under fire for causing chronic pain in 10-20% of cases.

See link:

This highlights the serious implications of what can go wrong. Could this have to do with improper DIS?

Be cautious.



Here at Koven’s cardiovascular innovation, we understand the pitfalls of inefficient DIS and innovate tailored solutions for every problem brought to our attention

When designing a product, it is very important to refine a comprehensive DIS so that your product does as intended without causing harm—and that is the bottom line.

So how do you know if your DIS is up to par?


Ian Maclean

As a medical device consultant, I offer up wealth of knowledge and guidance, especially in Design Input Specification development.

Many product developers utilize outsourcing; there are specific areas where high levels of expertise are required.

invite you to connect with me for a discussion. I am also available to hear any concerns you may have or to review your DIS if you want an outside perspective.

My name is Ian Maclean, let me be your expert.


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