Methods, apparatuses, systems, and implementations of an ultra-compact RF (30 GHz-10 THz) imaging sensor topology that provides a new insight into the human skin are disclosed. The skin tissue is the largest organ in the body—；both in weight and surface area—；and stores valuable information that can revolutionize security biometrics and mobile health monitoring. The proposed compact sensor enables, for the first time, portable and wearable devices to perform superior biometric authentication compared to current fingerprint methods. Additionally, these devices could probe into the skin to monitor vital signs in real-time and enable mobile health monitoring.
