A knocking-based, micro-combustion engine constructed in three layers of micromachined material. Two outer layers contain means for directing gases and fuels into and out of vents in a middle layer. The middle layer has machined in it two, linear, free pistons with or without integral air springs, and...http://www.google.com.tw/patents/US6276313?utm_source=gb-gplus-share專利 US6276313 - Microcombustion engine/generator
