This paper presents an optimized second generation electromagnetic (EM) MEMS power generator which can harvest energy from low frequency external vibrations. In the second generation scavenger, power is generated through planar electromagnetic induction using a magnet on the low frequency actuation plane, and coils on the high frequency resonance plane. It is demonstrated in this work through modeling and simulation that the generated power level is maximized by geometric optimization of the high frequency resonance plane. The geometric improvements in the diaphragm arms and magnetic actuation area within the MEMS device yield 318 nW maximum power and 23.8 mV maximum voltage. This corresponds to 2.6x improvement in output power, and 1.5x improvement in output voltage compared to previously reported design.