Definition of medical devices: refers to instruments, equipment, appliances, materials or other articles used for human body alone or in combination, including required software; Its effects on human body surface and in vivo are not obtained by pharmacological, immunological or metabolic means, but these means may participate and play a certain auxiliary role; Its use aims to achieve the following expected purposes: (1) prevention, diagnosis, treatment, monitoring and alleviation of diseases; (2) Diagnosis, treatment, monitoring, mitigation and compensation of operation or disability; (3) research, substitution and adjustment of anatomical or physiological processes; (4) Pregnancy control.