V S Veersamy & A Arbor of Michigan has developed a method for sensing the presence of moisture. The inventor was issued USP No. 7,516,002 in April, assigned to Guardian Ind Corp. The abstract released read: "A system &/or method for sensing the presence of moisture (eg rain) &/or other material/s on a window such as a vehicle window (eg windshield or backlite). In certain example embodiments, a capacitor-based system &/or method is provided for auto-correlating sensor data to determine the existence of a material on the window, & then cross-correlating sensor data to identify the type &/or amount of material. This data may be used to actuate &/or deactivate a vehicle's wiper/s, &/or adjust wiper speed. In certain example embodiments, the sensor may include an array of at least two capacitors. In certain example embodiments, the system &/or method may perform checks to enhance the accuracy of the detection by comparing, for example, the sign of autocorrelation values, maximum autocorrelation values and/or gradients of autocorrelation values."
