A non-contact proximity sensor with low frequency electromagnetic field

In this paper, a non-contact proximity sensor that is able to detect any kind of material with low frequency electromagnetic field is proposed. The sensor is simple and based on a single probe. In addition, it has two unique features which are flexibility of the probe and sensitivity to object thickness. After the theoretical analysis of the operation principle, experiments are given to analyze the validity of the theory and verify the ability of the sensor to detect object's proximity and thickness. Another experiment is also performed to examine the possibility of the sensor to detect the motion of the human heart. The sensor may potentially be applied in non-contact cardiac disease detection, micro-electromechanical systems (MEMS), cheap safe-guard system with one single sensor, thickness monitoring in standardization manufacturing, sport monitoring, and a lot of other places, etc.