Proximity sensors detect the presence of objects without any physical contact and have high reliability and a long operating life. There are many types of proximity sensors on the market, such as capacitive sensors, photoelectric sensors, laser, radar, and ultrasonic transducers. Different types of objects require different proximity sensing technologies. For example, capacitive proximity sensors or photoelectric sensors might be suitable for plastic targets, whereas inductive proximity sensors require metal targets. Unictron's ultrasonic proximity transducers have been widely used for short-range object detection for liquid, solid, and powder level detection. Their wide applications are not limited by the types of objects detected, regardless of colors, transparency, and hardness.