Detecting a phase of a short pulse

Hello everyone. I am trying to think of a simple circuit design, ideally using only passive components, which would light an LED if a pulse produces a positive voltage. Basically I have an analog system I am testing in which when I activate the sensor, I want to see a positive voltage swing, and then when I release the sensor it should produce a smaller negative voltage swing.

If the sensor is installed backwards, it instead would produce a large negative voltage, and then a smaller positive voltage.

I want to use passives to avoid the need for an external power supply. In my head, some sort of capacitor and resistor combination should be able to do this, but I am not sure on the design.