Medical products must be constructed as safe as possible for the approval of patients, users and third parties. To guarantee or ensure this, tests must be carried out by qualified personnel. senetics testing laboratories offers selected tests for functional, mechanical and biological safety. Functional safety has the aim of evaluate medical devices in such a way that every assumed technical defect is recognized in advance and does not present a hazard.
Functional Safety – Preparation
The different classifications of a medical device combined, are an important component in the safety philosophy. When it comes to classification, it is always necessary to determine: classify according to what? Application part, protection class, IP protection. The basis for this is the intended use including purpose and user groups. Define this at the beginning.
The next component relevant to functional safety is the classification of the application part after protection for the patient. Here the devices are divided into different classes according to their field of application and the devices must meet different requirements depending on the class. Where and when do users, patients and third parties get into contact with the device?
The measures for isolating the application parts in the insulation diagram are documented. Regardless of the EN 60601-1, further classifications for medical devices have to be made, a few of these are exemplified below.
The above stated classifications relate to protection against electric shocks. For medical devices, there are also classifications, which affect other devices, e.g. the IP classification according to DIN EN 60529 for enclosure protection.
Medical Device Classification
Depending on the application period and the type of application (invasive, non-invasive, etc.), medical devices are divided into different classes. This type of classification is not related to protection against electric shock and is defined in Annex IX of Directive 93/42 / EEC or soon after the new Medical Devices Regulation (expected in early 2017).
Documentation in the insulation chart
The easiest way to describe the electrical safety requirements of a medical electrical device is to use an insulation diagram. Although the term insulation diagram does not appear in the EN 60601-1, the appendices include a few examples of simplified “patient leakage diagrams”. Nevertheless, it is necessary for the approval, as it is part of the TRF. (TRF stands for Test Report Form of the IECEE. This template is used for CB reports by Notified Bodies.) For battery-operated devices, this is sometimes dispensed with or the approval office prepares it itself, since it turns out simple. For more complex devices with mains connection and several application parts, it is urgently necessary.
And a good insulation diagram has many benefits:
- It represents the safety-relevant parts of the device in the form of a block diagram
- It serves as the basis for improvements, ideas and alternatives within the project
- It serves as the basis for discussions with the Admission Board
- It shows possibilities in which it may be possible to lay down parting lines technically or financially
- It serves as the basis for the dielectric strength tests
- It can show possible hazards that might arise when connecting external devices at one glance
If e. g. a computer is connected via USB to the medical device and suddenly the patient is no longer separated via two protective measures to EN 60601-1 from the power supply
The insulation diagram is usually created by the HW developer of the device and then discussed with the TÜV if special specifications or assumptions are present.
(Source: Martin Bosch, Ingenieurbüro Madzar & Bosch)
Functional Safety of Software
The software has to be classified according to risks concerning the patient. This is a complex and interesting topic, but not the subject of this article. Depending on device type and requirements, there are other types of classifications that must be considered.
Software (stand-alone or as part of a medical device) must comply with the software life-cycle requirements of IEC 62304. In addition, it must have a high level of serviceability and must be taken into account in risk management.
senetics offers you various functional safety tests in a certified testing laboratory.
- Checking the product specification for compliance with RoHs and REACH
- Testing the suitability of a medical device for use in a magnetic resonance tomography
- Check for compliance with IEC 62304
- Test of electrical safety
- Emission test acc. EN 60601-1-2 up to 10 GHz
- Testing of rigid endoscopes according to EN 60601-2-18
- Programmable electrical medical systems IEC 60601-1-4
- Software lifecycle according to IEC 62304
- Usability and human factor according to IEC 60601-1-6 3ed