The largest source of design input is market research. Understanding the market gap for your product can help to understand what services need to be fulfilled by your product. From this market research, an outline of customer needs can be developed. The way to meet each of these needs will require detailed technical research that will outline the physical and performance characteristics of your device. The design inputs are the foundation of what the product will become. The source of all the data collected here will be highly concentrated in what is already in the market. Current market trends for the product specific medical industry will show what criteria needs to be met by the design. The higher level requirements which are the design inputs will soon lead to the lower level more specific outputs for the project after thorough technical research is performed.

In my point of view, I think there can be three types of sources of design input:
1. Modifying a similar design from previous models to suit our present needs
2. Using previous designs as a basis to create new and improved design, not necessarily similar or a replica of the previous design
3. Using two or more previous designs to crate a new design as a combination design

I will mainly talk about customer input sources. Every organization actually has two different types of customers: Internal Customers and External Customers.Most people are familiar with their external customers – these are your end users and even your intermediate users (dealers, distributors, brokers, etc).
If you’re in a regulated industry (and which ones aren’t these days), you’ll have Regulatory Agencies as another type of external customer.Your other customer, those internal ones, are extremely important when you’re designing a new product, process or service.For example, the manufacturability of your design or the serviceability of your design are very important to your internal customers (the manufacturing team or the service team)

Design Inputs should not just be the responsibility of one person. It's a team effort. When a team is involved, they will get the benefit of everyone's opinions and experience.
The other sources of Design Inputs like:
Industry standards, Regulations, Previous projects/products, Competitor products, End-users

Examples of design input: device functions, safety, standards, regulatory requirements, human factors, environmental limits, labeling and packaging.

Establishing solid design inputs are essential to the success of a project. Each and every single requirement to a product needs to be clearly stated and understood by everyone working on that project so that it can be developed correctly. The primary source for design inputs is usually the end users. Besides these people there are other sources that determine inputs such as industry standards, regulations set by FDA and other departments related to the product, products that were on the market before and products developed by competitors.

I think knowing what is the market need or work very close to your customer to understand the potential projects with them and knowing your company capability. you can analyze it and convert it to a valid input for a valid product that can help the market and the customer need. Also, design input not necessary to be a new product however it could be a new feature or adding to an exciting product as releasing a new revision of the same product with more option into it. In my opinion, the market needs in a specific industry can be transfer to input to a new product or project.

Design inputs are mainly customer needs. An individual can come up with an innovative idea for a medical device, however it is the design inputs that will ultimately dictate what goes into the device itself. These design inputs are basically the desires of the end users. Dr. Simon gave us a great example of a design input: "a red door knob". That would be an example of a design input. It offers a very generic quality about the device and is not specific. Think of what a client/customer would ask you to produce during the initial brainstorming of a device. Would a client come up to you and ask you to make "a 3-cm diameter knob dyed with Red #5" or would they ask you to make "a red door knob" with various other needs?

Nonetheless, a customer may want a specific function to the device that may not be feasible - according to the standards set out by the FDA, which @hzy2 had mentioned. Overall, the design inputs are ultimately shaped by the end users along with the standards and regulations of the FDA to ensure feasibility.

Design inputs are the foundation of medical devices, and so without a strong foundation it would be difficult to bring up the whole product. In a nutshell I would say that design inputs define all performance criteria, requirements, and features of the product. Some goals to considered are: Capture all functional, performance and safety requirements. Build user needs. Make clear objectives. State them in a way to prove and disapprove them. User is a primary source. Several other sources are: Industry standards, regulations, Previous projects products, end users, prototypes etc.

The user needs you have defined should be the primary source for your design inputs. When a team is involved, you get everyone’s experience and opinions, which will make the effort stronger. Besides user needs and the team, there are several more sources you should consider while defining design inputs: Industry standards, Regulations, Previous projects or products, Competitor products, End users and Prototypes. You need to consider all aspects of the medical device you are designing and ensure that you have defined all design inputs. You should capture everything, all criteria about your product, what’s important, how the device should perform, and so on.

Design inputs include customer needs as well as customer requirements. These are the aspects of the product that are expected to happen. For example, if you state that your product has a sensor that should flash red when interacting with a certain indicator, it should not flash green. These are the broader inputs that are addressed in the DID. The DSD document contains the more specific aspects of the product. Going back to that example, the measurements for the sensor, as well as the intensity of the green light should be stated along with a tolerance. Ultimately, the design inputs are what is expected to happen with the product with specific requirements.

To understand the importance of an input source leading to the design of a medical device, it only suffices to recall Dr. Simon's lecture Marketing - week 7. This lecture examines the volume of sales from the conception phase to obsolescence. It will be seen that the curve describing the sales trend is not a straight line. At one point - specifically toward the end - it enters a decline phase. What this means is that the value associated with the device essentially trends toward zero.

Now, who would want this their product?

Sales of their product is what keeps a company alive.

What we really want for our device is to find that the sales trend does not move into some decline phase.

Just to sight an example, the Stethoscope has been in the market since 1816 and instead of seeing a decline of its presence in the market we see more and more brands of the device spring into existence as time goes on.

What this translates to is that the source of intel preceding the design of a medical device is crucial.

Valuable discussion on this topic has already taken place. Sister Luisa Gutierres has, for example, delivered a brilliant discuss on the subject matter; but considering the importance of this subject, I believe we can use some more ideas from different perspectives on the subject.

Let us not lose sight of the fact that companies may have reasons to exist; hence, such promulgations as MISSION STATEMENT. That this statement is important to a company is seen in the fact that a company is willing to spend to keep its need to live on going. So if a management of the company can be convinced that design of a device will place the company in an enviable position, the bosses will be more than willing to dish out as much financial resource towards the existence of the medical device as may be needed. What I am really saying is that financial resources are a valuable input towards the design of a medical device.

In most lectures on Medical Device Development, Dr. Simon has essentially run out words with which to stress the value of getting inputs from potential the end user - the customer - of a medical device.

With he help of a prototype, the most valuable (sincere) intel can be fished from the customer.

Research on emerging technologies would be invaluable. Obviously there is competition out there; yet the customer fails to be satisfied. This emerging technological awareness integrated with a company's device is likely to give the company a competitive edge if, in integrating this technology with a company's medical device, consideration is focused on what makes similar devices fail to satisfy the existing customer.

These are not all, but are among the sources of intel that may be considered for exploitation.

Design input sources can vary depending on what could be the most efficient way to obtain them.
Many times, market analysis can offer significant information about a product. Technical research is also valuable to bring in an input of the best ways to create a product. However, these are not the only strategies that can be used for design input. Sometimes, it's very helpful to come up with a "proof-of-concept" that allows the audience to give feedback on the customer needs and to evaluate how the targetted audience receives the idea of the product. The feedback can be highly helpful to modify user requirements, and customer needs to ultimately come up with a good product.

Design inputs is important for medical devices and it will ultimately dictate what goes into the device itself. These design inputs are basically the desires of the end users.Some sources state that establishing design input can take easily up to 30% of the project timeline. Sometimes people are in a rush to get the product to market and give very little time to design input process.This is essential as it will build a strong foundation to ensure an easier and smoother path to market the medical device. Some good sources would be to obtain advice from a superior or those familiar with the design of your product to really ensure that it is feasible to create this project and for it to actually work effectively. The Goals of the design input should include user needs and intended use, safety, device functions, reliability, regulatory requirements. we need to consider all aspects of the medical device you are designing and ensure that we have defined all design inputs.

I agree with all of you that the main two point of design input is a market analysis or a customer needs/requirements. These two points are major for design input for industrial. However, from academia, it could be an idea or scientific research that trigger the input or the idea of the product. So I believe the source of design input could be different between the industrial point of view and academia. As industrial looking for a quick return from revenue-wise. you could think about design input as the foundation of the whole project.

Often it is not the end user that is the source of design input. Especially for medical devices, more technical design inputs are inspired by suggestions from surgeons and other medical practitioners. These inputs can be improvements on fit of an implant, or increase time between revision surgeries, etc. Over the years as more patients use the product doctors learn more about the patients needs.