The objective of this project is to design, fabricate, and assemble a 2.4 mm rotary internal combustion engine with integrated electrical generator and apex seals. The purpose of a such a tiny, on-chip electrical generator is to replace batteries with a power source that lasts much longer and is more environmentally friendly. The energy density of a liquid hydrocarbon fuel (such as gasoline) is much higher than that of most batteries. If the energy of the fuel can be converted into power at a 20% efficiency (an automobile engine's efficiency is typically 30%), then such a device would have 10 times the energy density of a battery. As a result devices powered by a tiny engine can be lighter than those powered by batteries or could operate longer for the same weight. In addition these devices could be "refueled" reducing the cost of waste and deposal typical of batteries.
The MEMS REPS 2.4 mm engine design has been completed. The engine is composed of a rotor, housing, shaft, and cover plate. The engine housing consists of two wafers Deep Reactive Ion Etched (DRIE) and die bonded together. Fabrication of the rear plate has been completed. The rear plate of the engine consists of intake and exhaust ports, fuel intake ports, and a spur gear. Since this engine is larger than its predecessor (1 mm engine) and the epitrochoid and the gear teeth are fabricated separately, spur gears with higher teeth counts are possible with a greater degree of accuracy. Test wafers show that even 50 tooth spur gears can be fabricated.