The design process of a medical device – Case: Serres Saga

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What is it like to design a medical device? What should be considered, and what expertise does such a product development require? Read about the work of Innokas Medical's Design Studio, and the process of designing Saga surgical fluid management system. There were several challenging elements in the device, but with expertise and cooperation in the design and manufacture of the device, the project was done effectively. Innokas’ knowledge of production and taking the device to production scale became the key elements in the project.

 

What product is Saga?

 

The Saga surgical fluid management system (picture 1) is a suction system whose task is to remove excess fluids that form during surgery into suction bags. The device can be used to manage large amounts of liquids safely, improve workflow and get real-time information to secure patient care and thus make the nurses' work easier. The device can e.g., calculate the amount of fluid entering and exiting the patient.

 

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Figure 1. Saga consists of three main modules: a control unit, a collection cart, and an irrigation pole. The collection cart contains suction bags and can be removed. The end user can have several collection carts and they can be changed, for example, in the middle of an operation and thus increase the collection capacity. 0-2 irrigation poles can be connected to the device as needed.

 

Saga's design work had already started with third parties before it was transferred to Innokas. It was a project, which purpose was to continue the design into a finished and productive product and to start manufacturing the product.

In one important part, the project was also a DfX design project, where special attention was paid to the design angle of Design for Manufacturing. The device was developed to suit better production scale and serial production, and its functionality was improved.

 

Steps in the design of a medical device

 

Saga's design is a good example of a project where the design of the device has already started in the company or another design office and comes to Innokas as an unfinished project. The design processes proceed on a device-by-device basis, depending on what has already been done and what is required of the device.

"Steps in the design process of a medical device include e.g., creating the requirement specification, concept proof, implementing and verifying the design," says Tapio Parkkinen, Senior Mechanical Engineer, Innokas Medical's Design Studio.

  • "The requirement specification clarifies what the intended use of the product is, and what requirements the device must comply with. Medical devices are divided e.g., into different categories based on the device's risks, operating environment, and users, and each category has its own requirements," Tapio explains.

  • In the concept proof, the product idea is clarified and tested more extensively from different perspectives. It depends on the device how these tests are carried out.

  • In the implementation of the design, the design is rolled forward: various prototypes are made, and the product is refined. Gradually parts and manufacturing are transferred to production.

  • "Lastly, the design process includes verification, i.e., official testing, which determines whether the device meets the requirements that have been set. Various tests are already carried out during the planning. In addition, production testing processes can be done, for example, to optimize the production of circuit boards", continues Tapio about the different stages of the process.


The result of the design is a validated end-product that meets the regulatory requirements and quality standards of the target markets and can be manufactured cost-efficiently.

 

Challenging structures and tolerance management


"Thinking about the design work, Saga had several demanding structures. The device has, among other things, several scales that are mechanically challenging for the scale to work properly. The device has welded subassemblies, vacuum functions, and a vacuum connection between the controller and the collection cart", says Tapio.

"The fitting of the controller and the collection cart to each other also requires careful reflection. Challenges were found in the design of tolerance chains. Tolerance refers to how a part is allowed to vary from another part so that they work together. In a large device, a tolerance chain is formed, and this should be kept as short as possible so that the device as an entity can be controlled. This is one of the most challenging things in the design of complex devices. The bigger the device, the more difficult it is to plan the tolerances", comments Tapio, especially about the challenges of mechanical design and continues:

"In the design, it should be considered that things can be fine-tuned and adjusted as desired and needed in prototypes, but this is not possible on a production scale. Usually, the challenge with tolerances is noticed at the stage when the product is started to transfer to production. "

 

With cooperation to the successful design


Design work often requires the input of many types of experts. The Saga's design process involved e.g., 4 mechanical designers, HW and software designers, testers, a DfX designer, and a project manager. In the most intense planning phase, more than 10 people were involved at the same time.

Also, cooperation with the client's organization was close, and the customer had responsibility and expertise, especially for the clinical side of the device.

 

The interplay of design and production


In the development of the device, it is of the utmost importance that design and production cooperate.

"It is important to communicate and think about the process together. Often the wisdom of how things are done best in production does not reside on the designer's desk. Even though a designer can take things far and nowadays there are many kinds of tools to help, such as 3D printers, things really become concrete in production”, comments Tapio.

Depending on the device, logistics chain planning, and packaging design also require consideration already in the designing phase: "How does the customer's order flow, how do the parts flow in production, what kind of package is the product sold in? How does the delivery take place sustainably and cost-effectively: does the product fit, for example, on standardized pallets, in which case the transport is significantly more affordable?" Tapio lists questions to consider.

 

Get it right at once


There are always challenges in large projects, but overall, the cooperation went well, and Saga's planning was done efficiently.

The project was engaging. "Personally, the most interesting thing was managing new technology, for example, vacuum technology and vacuum arrangements of this size class. I learned a lot through the project", says Tapio.

Key takeaways from the project were the importance of testing: it must be done several times along the way to avoid subsequent changes. When the product is approved and CE-marked, making changes is more laborious and difficult, especially with medical devices in terms of regulations and documentation. Making changes during the planning phase is much easier.

Ideas, projects, and products often have a busy schedule and cost pressures. Most of the product’s life cycle costs are solved in the design phase. When things are done right at once and investment is made in the design, savings are achieved in the longer term.

As seen in Saga's design, it makes a difference in succeeding in the design, when a design is done in a house that understands also manufacturing and changes can be done already during the design phase.

 

Designing since 1994

 

Innokas Medical has a long experience in designing and manufacturing medical devices. More than thirty experts work in our Design Studio. Design and production work closely and in continuous cooperation. Innokas Medical's expert and extensive QA/RA team helps ensure that the product is created according to the requirements, and our own software house Digious is also part of the projects when needed.

 

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