A vibration electrode plate 112 is formed on the upper face of a silicon substrate 32 with an insulating coat film 35 interposed in between. The macroporous copolymers can be made using an interpenetrating polymer network techniques. In specified positions of the outer frame and the partitioning part of the dynode, glass receiving parts wider than the outer frame and the partitioning part may be provided integrally with the dynode. The extension is restricted such that the vane does not contact the inner diameter of the engine block during at least a portion of a combustion stroke.