the sealing system 37 of the aperture 14 flexibility of the sealing system 37 can also be controlled by the cross sectional configuration including controlling thickness of the arm and walls supporting the capacitive sensor in the embodiment shown in fig4 the capacitive sensor 32 is molded directly into the sealing system 37 referring to fig5 wherein like primed numerals represent similar elements in an alternative embodiment the capacitive sensor 32 u2032 may be added as an aftermarket item by using adhesive 39 to attach the capacitive sensor 32 u2032 to the sealing system 37 u2032 referring to fig2 a door 36 of a motor vehicle 16 is shown the door 36 defines the aperture 14 a window frame in this case as an opening extending between a base 38 of the door 36 and around a window frame 40 having a forward boundary 42 an upper boundary 44 and a rearward boundary 46 the capacitive sensor 32 extends along the forward 42 and upper 44 boundaries the capacitive sensor 32 is designed to measure the electromagnetic field directly therebelow within the aperture 14 the capacitive sensor 32 is preferably a long conductor that extends out from and along a window frame 40 at a predetermined distance from the window frame 40 the predetermined distance creates.