When Michael Faraday introduced the concept of an electric field, little did he realize how far science would run with the idea. Today, engineers are using electric fields to sense the presence of other objects without relying on physical contact. Referred to as e-field sensors or capacitance sensors, they are becoming more and more prevalent in a wide range of inexpensive and long-lasting applications. When you take a closer look at how they work, you quickly see why their popularity is growing.