UDI即Unique Device Identifier，器械唯一识别符，指满足CFR part  830.20要求的，通过其分销和使用来充分识别一个器械的一种识别符。UDI是一种数字或字母编码，由两部分组成，分别为器械识别符(device  identifier, DI)和生产识别符(production identifier,  PI)。

Device labelers are required to submit information to the FDA-administered Global Unique Device Identification Database (GUDID). GUDID includes a standard set of basic identifying elements for each device with a UDI and contains ONLY the device identifier (DI), which serves as the key to obtain device information in the database. GUDID does not include the production identifier (PI).