Posts Tagged ‘design engineers’

Systems Engineering In Medical Device Design – Preproduction, Part I

Monday, February 4th, 2013
     If you’ve been following along with our blog discussion on the systems engineering approach to medical device design, you should by now be convinced that instructions are important.  In fact, the meticulous instructions produced during the manufacturing, operating, and maintenance  phases of the Development stage are also crucial to later stages, that of Production  and Utilization.  Let’s finish up our discussion on the Development stage by taking a look at its final aspect, Preproduction.

     The Preproduction aspect is instrumental to nipping potential problems in the bud before the medical devices go into actual production.  In the initial Preproduction stages, systems engineers coordinate with the manufacturing and purchasing departments within the company as well as outside suppliers.  The goal is to acquire all parts and equipment necessary to build a limited number of medical devices on the assembly line.  Subjects such as preference in molded plastic components, motors, gears, pumps, springs, electronic components, circuit boards, wire, and tubing are discussed and agreed upon.  Vendors are assessed with regard to their ability to produce parts when they are needed and that meet design specifications, satisfy quality requirements, and have costs that fall within budgetary constraints.

     The assembly of Preproduction devices provides an opportunity for systems engineers to validate manufacturing and quality control instructions and assess the device design with regard to manufacturability, meaning, the extent to which devices can be manufactured with relative ease, at minimal cost, while maintaining maximum reliability.  Devices manufactured during this aspect of the Development stage serve as a test.  Are instructions clearly written?  Do the device parts fit together as they should?  Are parts strong enough to withstand the assembly process?  Can the devices be assembled as quickly and easily as expected?

     If the answer is “no” to any of these questions, then the device design and instructions must be returned to the design engineers and technical writers.  Heads come together to rehash things and work out the bugs.

     Next time we’ll continue with the Preproduction aspect of the Development stage to see how laboratory and field testing enables systems engineers to shake out any more bugs from the medical device design, operating instructions, and maintenance instructions.


Medical Device Design

Systems Engineering In Medical Device Design – Instructions, Part 4

Sunday, January 27th, 2013
     Last time we wrapped up our discussion on the development of quality control instructions for use during the Development stage of the systems engineering approach to medical device design.  These instructions are used to guide quality control inspection and testing during the Production stage.  Now let’s continue our discussion on the development of instructions for the Utilization stage, the stage when the medical device is actually put into operation by the end user.

     In the systems engineering approach to medical device design, design engineers must work closely with technical writers, those responsible for writing operating and product service instructions.  The objective here is to share the engineering staff’s intimate knowledge of the medical device’s design with the writers in order to ensure that instructions are clearly written, comprehensive, and follow a logical progression.  Instructions must be written so as to be easily understood by lay people outside of the engineering profession and medical device industry, because most of the individuals using the device will be healthcare professionals and service technicians, individuals lacking a background in engineering or medical device development.

    Instructions are not only meant for the eyes of end users.  They are also subject to review by governmental agencies.  This fact acts as a safeguard to ensure device compliance both with regulatory requirements and industry standards as regards cautions and warnings.  For example, instructions may be required to caution the user to allow the device to warm up for a certain period of time before use to avoid patient discomfort when coming into contact with cold metal.

     Instructions might also warn against a harmful interaction if the device is used in conjunction with other devices. For example, an electronic muscle stimulator may send electrical pulses into a patient’s body that can interfere with the operation of their heart pacemaker.  No doubt this is something that the operator of the device and the patient would want to be informed of.

     At this point our medical device design has been completed, and instructions and procedures written, but the Development stage is not yet complete.  Next time we’ll continue our discussion on this stage to see how a systems engineering step helps us to be safe rather than sorry after full production of the device has begun.


medical device design

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.