3D human proximity sensor based on the AC hum effect

Human proximity sensors are currently being employed in a variety of applications such as individuals' safety, touch-less interfaces, securing valuables, etc. Especially, 3D types are more attractive as they offer robust and accurate detection results. Popular technologies for implementing such sensors include infrared, acoustic, capacitive, and RF techniques. Implementation cost, system complexity, and detection range are some of the challenging design requirements. In this paper, we propose a simple, low-cost, passive 3D proximity sensor based on the AC hum effect on the human body offering a relatively large detection range of up to 50cm.