Automatic Battery "ON/OFF" Circuit, Analog or Micro?

I have an interesting challenge where I need to automatically turn on a circuit that is powered by a single 1.5V battery and that battery is the only source of power. I need the circuit that is powered by the battery to be "off" and switched on when a tiny sense current is detected and then I need the circuit to be "switched" or powered on. The catch is, I need whatever detection scheme to be essentially zero current until there is a current sensed so the battery lasts for years. I've been tinkering with high side current monitors but the lowest operating voltage I can find is 2 volts and up, not to mention their quiescent current is pretty high. Not going to work for a single cell battery operated circuit. I need the circuit to be off unless there is 1uA of current or more being drawn through the auto on sense circuit I dont have yet. I think I need a MOSFET GURU to help me find a low voltage MOSFET that can be turned on some how when any current is drawn by the sense CKT. Past that, I'm clueless! Off is the other challenge. I am hoping to be able to use a capacitor to make some sort of RC timing CKT that holds the on/off CKT on for a period of several minutes before the whole thing shuts off again. If the auto on sense CKT continues to sense current being drawn through the separate detection path, that should continue to retrigger the RC CKT to stay on. If this can all be done in a pico-power micro that can be coded to go into a deep sleep @ less than uA when off, then I'd go off in that direction as long as the micro is very small.