Low-power detect rise and fall of input signal
You can generate a pulse on any edge of a signal using some logic gates. For instance combining a rising edge detector with a falling edge detector and adding a time delay would probably achieve what you want:







simulate this circuit &ndash; Schematic created using CircuitLab

Simulate it here.

The length of time the pulse is on for is (roughly) defined by the time constant of R1 and C1.  That's T=RC, so in this instance 100 x 0.0000001 =  10uS.

for a time of (say) 30 seconds, you will want to massively increase those values. For example, 470uF and 80K would give you around 32 seconds. 

Power consumption? Well, that's all dependent on the logic gates and how you build the circuit.  74HC chips are pretty efficient now (far better than the old 74LS ones), but you will want to reduce it down to as few chips and gates as possible. That means converting the circuit to just one gate type (for example NAND) and reducing redundancy in the circuit to minimise power consumption.