Reading the Document “8–13 Hz Fluctuations in Rectal Pressure Are an Objective Marker of Clitorally-Induced Orgasm in Women” it shows a graph of rectal pressure against Frequency; and Time:

As you can see there is a marked difference in pressure against time during Orgasm than during tasks. One way to sense this would be the use of a pressure sensor coupled with an inflatable butt plug.

In theory the but plug would be inserted into the young lady; inflated till it was under pressure; the valve would then be closed; the analogue value read from the Pressure Sensor as a zero point.

With a little bit of signal processing you could abuse the feedback to turn off other machines before or during orgasm; and also hopefully before…

Now to purchase a few sensors and try it out.