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What is a 'medical device'?


Medical devices are generally defined as articles which are intended to be used for a medical purpose. The medical purpose is attributed to a product by the manufacturer.

According to the European Medical Device Directive (2007/47/EC) which amended European Medical Device Directive (93/42/EEC), a medical device is -

'... any instrument, apparatus, appliance, software, material or other article, whether used alone or in combination, including the software intended by its manufacturer to be used specifically for diagnostic and/or therapeutic purposes necessary for its proper application, intended by the manufacturer to be used for human beings for the purpose of:

- diagnosis, prevention, monitoring, treatment or alleviation of disease;
- diagnosis, monitoring, treatment, alleviation of, or compensation for, an injury or handicap;
- investigation, replacement or modification of the anatomy or of a physiological process;
- control of conception;

and which does not achieve its principle intended action in or on the human body by pharmacological, immunological or metabolic means, but which may be assisted in its function by such means ...'

This new directive came into place on 5 September 2007 but will not be in force until March 2010

The annexes to the directive (denoted by the Roman numerals) are most important to manufacturers. Below is a brief explanation of some of the relevant annexes:

- Essential requirements for all Products (I);
- Applicable Conformity Assessment Procedures (II, III, IV, V and VI);
- Manufacturer Declarations (VII);
- Classification of Products and Definitions (IX);

- Clinical Evaluation (X).

Two other relevant European Directives are:

  1. Active Implantable Medical Device Directive (AIMDD) 90/385/EEC.
  2. In Vitro Diagnostic Medical Device Directive (IVD) 98/79/EC.

Further information

TWI provides its Industrial Members with technical support in a broad range of areas including device design, materials selection, reliability, durability, joining and coating methods and manufacturing procedures - there are overfifteen scientists and engineers with direct knowledge and experience in medical device developments and extensive range of facilities supporting TWI's medical sector activities.

Electronics, sensors and medical industries - TWI expertise and support services.

Classification of devices is covered by Directive 93/42/EEC

Currently TWI also manages the Health Technologies Knowledge Transfer Network (HTKTN). The website of HTKTN ( contains extensive information on medical device related activities

For more information please email: