SaMD refers to software intended for medical purposes that operates independently from any hardware medical device. It performs medical functions on its own, without being embedded in a physical product. Examples include AI-powered diagnostic tools, mobile applications for disease risk assessment, or cloud platforms that analyze patient imaging data. SaMD plays a central role in digital health because it can be deployed quickly, updated remotely, and used across diverse care settings.
SiMD is software that is integral to a physical medical device, enabling, driving, or controlling its primary functions. It cannot operate on its own and is validated as part of the device it is embedded in. Examples include firmware in infusion pumps, control logic in pacemakers, or image reconstruction software in MRI machines. SiMD is tightly tied to the parent device’s functionality, meaning that changes to the software directly impact the regulatory and technical status of the device.
While both SaMD and SiMD fall under global medical device regulations, the classification and approval pathways differ. Authorities evaluate them based on integration, risk, and clinical impact.
| Aspect | SaMD | SiMD |
|---|---|---|
| Integration | Operates independently | Embedded within a device |
| Regulatory Pathway | Classified as a medical device on its own | Assessed as part of the parent device |
| Updates & Changes | May require separate regulatory submissions | Covered under the device’s regulatory approval |
| Risk Assessment | Based on intended use and clinical context | Based on device function and patient impact |
In the EU, the Medical Device Regulation (MDR) explicitly classifies both SaMD and accessories, while SiMD is regulated under the parent device submission. The FDA makes a similar distinction: SaMD is regulated as an independent device, while SiMD is tied to the overall device approval. The IMDRF framework provides harmonized guidance for classifying and regulating SaMD globally.
SaMD examples:
SiMD examples:
These examples highlight the regulatory distinction: SaMD must stand alone in its regulatory file, while SiMD is validated through the device it supports.
Understanding the difference between SaMD and SiMD is critical for developers and manufacturers because the classification determines:
For manufacturers, the key takeaway is that software strategy must be aligned with the intended use and integration model. Early classification decisions shape regulatory timelines, market entry strategies, and compliance costs.
