Medical Electronics
Designing for medical devices
Cochise Mapa looks at the various design factors that need to be taken into account when designing a suitable power supply for a medical device
W
hen it comes to manufacturing power supplies for electronic equipment, many design factors
must be considered such as operating performance, efficiency, density, form factor, environmental conditions, and global safety approvals. Clearly for medical devices, power supplies are required to meet very exacting standards as defined in the IEC 60601-1 3rd edition, effective June of 2012 for Europe.
While power is a critical component for any medical electronic device, most medical device OEM designers put off power supply design and power management options until near the end of the medical device design cycle. The choice of power supply unit (PSU) is relegated to picking a medical safety certified PSU that meets specified device parameters. However, specific applications, environmental conditions and even findings from adverse events of electro- medical device failures have pushed clear demands on capabilities on a better PSU.
New standards The IEC 60601-1 standard is a globally recognised standard for electro-medical equipment safety. The next evolution in the IEC 60601-1 third edition requires a risk management file and process conforming
24 October 2012
to ISO 14971, the international standard for Application of Risk Management to Medical Devices.
Medical device OEMs are required to meet this standard for their end products and are responsible for the risk management and applications categorised as Means of Operator Protection MOOP or Means of Patient Protection MOPP. Even though the 3rd edition standard really does
not apply directly onto components, leading power supply manufacturers are working closely with their medical device customers to comply with this new regulation. For next generation medical device products, it is easier to start requiring power supplies certified to the 3rd edition. For existing electro-medical devices especially those in the EU market, complying may mean re-qualifying another power supply through end-device verification and validation or doing risk assessment of the continued use of current power supply.
Risk management
Risk Management covers risk analysis and evaluation followed by risk control to
bring overall risk to an acceptable level, with a continuous monitoring and feedback process. Below is a table typically used to identify hazards and conditions affecting safety and critical performance of the medical device, to gauge the severity of harm done, identify the cause of the condition, to assign probability of occurrence and to define activities to mitigate the risks. To include the power supply in the risk assessment, the medical device product team (i.e. staff coming from regulatory affairs, engineering, marketing, quality, etc.) should consider feedback from their power supply partner in identifying the hazard conditions as well as the probability of those events occurring. The
Table 1: Power risk analysis Components in Electronics
www.cieonline.co.uk
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