Posts Tagged ‘systems engineering’

Systems Engineering In Medical Device Design – Concept Evaluation

Monday, December 17th, 2012
     How many times have you bought something and lugged it home, only to discover that it didn’t work as advertised?  These days this scenario is all too common.  Chances are it was developed haphazardly and rushed into production without adequate research and testing.  A chief contributor to the product’s not living up to expectations is very often the result of a poor beginning.  In its concept and development stages, design engineers failed to use a systems engineering approach.

     Last time our discussion of the Concept stage of systems engineering identified stakeholder requirements as being of three basic types, serving the needs of functionality, performance, and constraint.  Once identified, these requirements were incorporated into a detailed specification that is approved by all stakeholders involved, then used to devise alternate medical device concepts in order to really size things up.  Let’s now move on to the Development stage of the design process to see how the alternate concepts are evaluated.

     The Development stage of the systems engineering approach to medical design begins with research and development of alternate device concepts.  Stakeholder requirements as defined in the original product specification are used to guide the process, then mockups and prototypes of the alternate concepts are built, tested, and analyzed in view of the requirements.  Considerations such as cost, ease of manufacture, operation, durability, and potential risk of harm to users are evaluated.

     As often happens, the best alternate concept satisfies all but a few of the specified requirements, resulting in a “good enough” scenario.  That is to say, if stakeholders can agree the requirements not met aren’t all that important in the scheme of things, they may be willing to remove them from the specification, thus approving the concept for further development.  If an agreement such as this cannot be reached, it may be necessary to return to the Concept stage and begin the entire process again.  This re-evaluation of the process should result in a set of requirements that are further refined and from which better options in alternative concepts can be developed.

     Next time we’ll continue our discussion of the Development stage and see what it takes to finalize design and begin manufacture.


Systems engineering in medical device design.

Systems Engineering In Medical Device Design – Concept and Requirements

Monday, December 10th, 2012
     Last time we introduced the first phase of the systems engineering approach to medical device design, the Concept Phase.  It’s a phase which emphasizes clear communication between design engineers and stakeholders in the project.  Effective communication results in clearly defined stakeholder requirements.

     Stakeholder requirements are of three basic types, serving the needs of functionality, performance, and constraint.  A functional requirement is a basic starting point, specifying the tasks to be accomplished by the system and its basic operation.  For example, a medical diagnostic imaging device can be required to operate on a dedicated 15 amp branch circuit when plugged into a 115 volt wall outlet.

     Performance requirements delineate specific expectations as regards the system’s functionality, typically specifying parameters within which the system is to perform.  For example, a medical device can be required to process a minimum number of test samples per hour.

     As for constraint requirements, they’re typically concerned with satisfactorily complying with both governmental regulations and industry standards.  Governmental regulations include those established by the US Food and Drug Administration, as well as any applicable foreign agencies that may be involved should the medical device be introduced to other countries.

     Once the draft specification is written, design engineers review it in painstaking detail.  Stakeholders’ requirements must all be accounted for and interpreted correctly.  This is typically done by sitting down with each stakeholder and reviewing the draft.  Finally, each stakeholder’s signature is obtained, signifying their approval.  Now complete, the approved specification is used as a roadmap to guide project development through to the next and final step of the concept stage, devising alternate medical device concepts.

     Why discuss alternate concepts?  Just like consumer comparison shopping for TVs and other goods, you’ve got to have a basis of comparison in order to make a sound judgment.  This holds true for the medical device industry as well as private households.

     Next time we’ll proceed to the next stage of the design process, Development.  We’ll see how alternate concepts are evaluated to find the best overall option, thus beginning the actual design process leading to manufacture. 


Systems Engineering in Medical Device Design

Systems Engineering In Medical Device Design – Concept and Communication

Monday, December 3rd, 2012
     “Ask and you shall receive,” like “Make your thoughts known,” have the same objective, to initiate a dialogue between someone with a vision and those who can get the job done.  In other words, if you don’t ask for it, you’re probably not going to get it, and the moving force behind it all is communication.  Communication is as important in design engineering as it is in marriage.

     Last time we learned that a system is a combination of interacting components organized to achieve one or more specific purposes and that communication is a key ingredient in the process.  Now let’s see how the systems engineering approach is used within the medical device design process.

     The systems engineering approach consists of five key stages, the first being Concept.  In this stage the objective is to identify all stakeholders, that is, those who have a stake in the outcome, then exhaustively define and capture their requirements.  Crucial to this stage is a good line of communication between design engineers and stakeholders.  This usually takes the form of brainstorming sessions in which all parties meet to toss around ideas.  These ideas eventually solidify into design requirements.

     Once the design requirements are identified, they are incorporated into the first draft of a working specification.  This specification will be written using plain English to minimize any potential misunderstandings.  Within the specification each requirement is not only well defined, but traceable back to whoever proposed it.  To this end, all requirements are listed in tandem with the names of stakeholders proposing them.  Accountability is the main concern here.

     Next time we’ll talk more about these design requirements, and how they must serve the needs of functionality, performance, and constraint.


Systems Engineering Communications in the Concept Stage

Systems Engineering In Medical Device Design – Introduction

Monday, November 26th, 2012
     I once worked with a medical device design engineer who, although talented enough, was not adept in the subtle yet indispensable skill of verbal communication.  He lacked a concise, organized approach to his projects, and his problem solving skills were unilateral and obtuse, that is to say, his only aim was to satisfy his personal requirements, what he felt was important.  Creative problem solving and brainstorming with customers as to what they desired did not fall within his repertoire.  As a result customer complaints and a long string of product failures eventually led to him losing his position.

     Where specifically had he failed?  The net result of his approach was that he designed devices that did not deliver the desired customer results.  They also had a varying tendency to be either unnecessarily expensive to produce, unreliable to operate, or difficult to service.  All concerned with the product were often dissatisfied, from customers to service technicians.  This caused the company we worked for to incur considerable expense to rectify his design errors.  The company also lost some of their customer base to competitors.  Sadly, none of this would have happened if my coworker had used a systems engineering approach in designing his projects.

     Before we get any further into a discussion on systems engineering, let’s get a handle on what is meant by a system.  In a nutshell, a system is a combination of interacting components that are organized to achieve one or more specific purposes.  The components can be tools, machine parts, electronics, people, or any combination thereof.  For example, hundreds of parts can be combined by a manufacturer into a system to form a medical device such as an x-ray film developing machine, the end result of which is to produce a film of diagnostic quality. 

      The system part of Systems Engineering stays true to this definition. It is an interdisciplinary approach to complex engineering projects which guides all activities during the course of a product’s life cycle, from conception to production. While doing so it will integrate and monitor work processes between all departments involved, with a constant eye towards optimization of processes and reduction of costs in order to satisfy stakeholder requirements.

     A key objective of systems engineering is to produce systems that satisfy stakeholder needs by producing reliable, cost effective, and safe products capable of performing tasks as designated by the customer.  Within the medical device arena stakeholders include patients, nurses, doctors, the US Food and Drug Administration (FDA), device service technicians, device dealers, as well as the device manufacturer.

     Next time we’ll begin our exploration of how systems engineering addresses the medical device design process with a discussion on the first of its five stages, known as Concept.


 Systems Engineering In Medical Device Design

Medical Device Design Controls – Planning and Input

Sunday, August 29th, 2010

     Have you ever had the divine experience of remodeling a major-use room of your house?  Was the general contractor you employed able to understand what you wanted, plan out the work according to your requirements, and finish the job to your satisfaction?  Maybe you had the unfortunate experience of hiring one that forgot your requirements, made things up as they went along, and stuck you with a room that looked awful, violated building codes, and didn’t meet your needs.

     Now imagine what would happen if a medical device company took this haphazard approach to designing new products.  Suppose the company’s engineers ignored the input of regulatory, marketing, procurement, quality control, and manufacturing staff?  What if they chose not to follow applicable industry standards for performance and safety?  And what if they failed to check design calculations or test prototypes for errors before putting the device into production and introducing it to the marketplace?  The result is likely to be unfavorable, just like your contractor forgetting that you wanted a black granite countertop, not a beige one.

     To help eliminate painful and costly scenarios such as these, the FDA requires that medical device manufacturers establish and maintain procedures to control the design of  Class II and III devices, and even some Class I.  This requirement for a system of design controls is part of the Quality System Regulation (QSR) under Title 21 of the Code of Federal Regulations.  In case you’re not too familiar with the Code of Federal Regulations, Title 21 gives the FDA legal authority to regulate food, drugs, and medical devices in the United States.

     So what falls under the premises of FDA design controls?  Well, the FDA requires that a medical device company develop procedures for:

  • • Design and Development Planning
  • • Design Input
  • • Design Output
  • • Design Review
  • • Design Verification
  • • Design Validation
  • • Design Transfer, and
  • • Design Changes

For now, let’s focus on Design and Development Planning and Design Input Procedures.

     In the Design and Development Planning Procedure companies must carefully plan who will be involved in each phase of product development, as well as how they will interact, all in an effort to ensure that information flows and design requirements are met.  The right pool of people would include design engineers, in addition to those employees responsible for making sure that regulations are complied with and those who are charged with securing intellectual property rights to the design.  Then there are those who must acquire the physical materials required to manufacture the device and those who will do the actual manufacturing of it.  Also, those responsible for quality control, marketing, sales, and product service should be involved.  Perhaps others should be involved as well.  Mind you, the Design and Development Planning Procedures are not set in stone.  They must be regularly reviewed and updated as the project evolves.

     Now let’s talk about Design Input, which is another term for a design requirement.  These inputs can come from inside or outside the company.  An example of a requirement coming from within is when Marketing stipulates that the maximum manufacturing cost of the device should not exceed $150 in order to maintain an acceptable margin of profit and be most competitive in the marketplace.  A design requirement coming from outside the company would include industry standards that make specific requirements, such as requiring that the device in question be designed to protect its electronics from radio frequency interference. 

     Next time we’ll continue our discussion on medical device design by exploring Design Output, Design Verification, and Design Review Procedures.