Posts Tagged ‘instructions’

Systems Engineering In Medical Device Design – Preproduction, Part 3

Monday, February 18th, 2013
     We’ve been discussing the Preproduction aspect of the Development stage of our systems engineering approach to medical device design.  Last week we learned that once the medical devices produced during Preproduction are assembled, they’re subjected to rigorous testing, first in the lab, then in the real world.

     Once devices produced in Preproduction pass the test in a controlled laboratory environment, it’s time to place them into field testing.  The objective is to place Preproduction devices within actual working environments, such as healthcare facilities.  These facilities must be willing to cooperate with design engineers during testing on a number of items, including but not limited to evaluation of product performance and clarity of instructions.

     In order for this to happen, design engineers must coordinate their efforts with their company’s sales and marketing departments to locate, qualify, and enlist suitable facilities.  To qualify, a facility must be able and willing to put enough hours of use onto the test device to effectuate a thorough and complete analysis of its effectiveness.  Depending on FDA regulatory requirements and the complexity of the design, field testing could take as little as several months or as long as several years.

     During field testing valuable data is gathered to enable engineers to evaluate the performance of the Preproduction devices.  This data will then be measured up against stakeholder requirements.  What this process might entail in a dialysis machine, for example, is that test data is analyzed to make sure all operational parameters fall within the desired range.  Data would be derived from measurements of such things as the pressure of blood flowing pre- and post- introduction to the dialyzer.  Measurements are dutifully recorded by engineers and field personnel onto data sheets for later evaluation back at the manufacturer’s engineering office.  Persons contributing data vary widely, from healthcare facility end users and maintenance personnel, to the medical device dealer’s service technicians.

     End users also provide feedback to design engineers regarding the field test device’s functionality, effectiveness, reliability, and maintainability.  Feedback can include specific information about things like glitches in software, unusual noises, erratic operation, breakdowns, and even difficulties encountered during repairs.

     If any problems are discovered with the device during lab and field testing, revisions are made.  Design engineers and technical writers get back to the drawing board to rework things and find resolutions until all issues have been addressed.  Only then is the design presented to stakeholders for final approval.  If all goes well, manufacturing will now take over and place the device into full commercial production.

     We have now concluded our discussion on the Development stage of systems engineering as it relates to medical device design.  Next time we’ll move on to the Production stage where we’ll examine post-production concerns.


medical device field test data

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 3

Sunday, January 20th, 2013
     Last time we looked at the objective of the quality control department in the Production stage, that being to ensure that the end product produced fits all requirements.  We learned that to meet this objective a great deal of collaboration must take place in the Development stage between quality control staff and design engineers in order to produce a complete set of instructions for quality control inspection and testing.  Now let’s see how these instructions are developed.

     Inspection and test methods are devised by the quality control department to ensure that a completed medical device lives up to its intended use.  What good is a diagnostic imaging machine that doesn’t provide accurate internal views of a patient’s body?  Or a heart defibrillator that sends electrical energy pulses to a patient’s heart muscles when it’s not supposed to?  Quality control instructions are developed to guide inspection and testing methods so they’re performed correctly and consistently during the medical device Production stage.  The objective is to catch problems before they occur.

     For example, it can be specified that the plastic body components of a medical device be visually inspected after they are received from an outside vendor to check for undesirable defects, such as the presence of burrs, cracks, or non-uniform coloration.  If anomalies are discovered, they’re documented, and the components are rejected.  In other words, they are barred from being used in the assembly process.

     Quality testing methods are varied.  They may involve hooking up the completed medical device to test instruments to simulate all possible modes of operation and any anticipated glitches that may occur during testing.  While hooked up, the device’s operation is measured against key parameters to ensure that all is working well, and the data gathered is recorded and analyzed to see if operation is within normal limits.  For example, an electric multimeter could be connected to the power cord of the device to measure how much electrical current is being drawn from the wall outlet during operation.  If current drawn is too high, it may be indicative of a defective electrical component, and an in depth examination would follow.

     Generally speaking, if test measurement parameters do not fall within acceptable limits as determined by previously established stakeholder requirements, then the medical device will be rejected by quality control.  It will then be sent back to the manufacturing department, along with a detailed inspection and test report explaining why it was rejected.  At this point the rejected device is either reworked or disposed of entirely.

     Next time we’ll continue our discussion on the development of instructions for the Utilization stage, the stage where the medical device is actually put into use by the end user.


Medical device engineering expert.

Systems Engineering In Medical Device Design – Instructions, Part 2

Monday, January 14th, 2013
     Last time we discovered that clearly written instructions are one of the desired end results of the Development stage of the systems engineering approach to medical device design.  We learned that one of the objectives of these instructions is to make sure the devices are manufactured in a cost effective manner and with minimal defects during the Production stage. 

    Other instructions created during the Development stage are those addressing quality control inspections and testing instructions.  The objective of the quality control department is to ensure that, during the Production stage, the end product has been assembled correctly, making use of the prescribed parts, and absent manufacturing defects.  This end is achieved by virtue of the fact that the quality control department staff is usually not under the management of the engineering or manufacturing departments, therefore they are positioned to offer an impartial assessment of the production process. 

     An undesirable side effect of quality control’s impartiality is that because they are not intimately involved in the design process, a great deal of collaboration must take place between them and design engineers to produce quality control instructions which meet objectives.  To this end, many discussions must take place concerning subject matters as diverse as requirements for component dimensions, component material properties, and the proper assembly of parts.

     Next time we’ll continue our discussion on the Development stage by further examining how instructions are developed to ensure that the quality control department meets its objectives while performing inspections and tests during the Production stage.


Medical device quality control.