Various techniques are described herein for using smell sensor-based Internet-of-Things (IoT) devices to detect and identify individual users based a unique scent or smell print. Interconnected networks of such devices may be used in collaboration, along with other devices such as IoT devices and home monitoring system devices, to track user movements and activities. Such smell sensor device also may be used to detect weapons, explosives, narcotics, and other prohibited items that may be concealed and/or not detectable using security cameras. The data received from the smell sensors and smell-based IoT devices may be used, alone or in combination with other security sensors and systems, to perform safety and security screening within homes, airports or other secure areas, or within any public indoor or outdoor location.