Posts Tagged ‘electrical energy pulses’

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.