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The PC as a Medical Device
It is very convenient to design medical devices based on the PC hardware platform. However care must be taken to ensure
that the resulting product complies with the requirements of IEC 60601-1.
Power Supply
A standard PC power supply almost certainly does not comply with the electrical IEC 60601-1 requirements from several
standpoints, e.g. leakage current requirements, dielectric strength requirements. There are two possible solutions:
- Replace the standard PC power supply with a power supply which has been designed to comply with IEC 60601-1.
- Power the PC via a 1:1 isolation transformer, which has
been designed to IEC 60601-1.
The second route is preferable if there are additional pieces of the equipment (e.g. computer screen), which also need
powering, as they also can receive their power via the isolation transformer. The first route is advantageous from the standpoint of size and weight.
Note that in any case the PC used should be approved to the appropriate safety standard for IT equipment, i.e. IEC
60950, or its national variants, EN 60950, UL 1950…
Simply powering a PC via a medical grade isolation transformer or an IEC 60601-1 approved power supply is not sufficient
to ensure that the device complies with all the requirements of IEC 60601-1.
Some additional points are noted below:
- Patient connections, particularly Type BF and Type CF, must be isolated from other secondary circuitry used for
signal input/output ports. This protects the patient if, as a result of faults on external equipment, dangerous voltages appear on communication lines.
- Any communication ports which are not part of the medical device, should be blocked off so that they cannot be used.
- Connectors on patient leads must not be of a type in common use, e.g. 9-pin D-type, keyboard connector, etc., to
prevent the possibly of the patient being inadvertently connected to an unsafe device or port.
- The PC must not have red or yellow indicator lights, buttons or switches, as these have special meaning.
- If there is a requirement for the product to prevent the ingress of liquids, then the PC used would have to comply
with the appropriate level of prevention of ingress of liquids.
In order to ensure that the device is fully compliant with all the requirements of IEC 60601-1 or UL 60601-1, it must
be submitted to an accredited test laboratory for investigation.
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