Some design considerations

fabrication issues and structure improvements of siliconbased micro electrostatic motors are described.On-chip detection of micromotor rotational speed

which is significant for studying micromotor dynamics and constituting MEMS

is realized by integrating photovoltaic devices on silicon substrate beneath the rotors.A cone bearing structure

which reduces the friction

is obtained by use of SiO2/PSG composite sacrificial layer technology.The preliminary measurement results show that the mininum starting voltage of micromotors is 93V and the maximum rotational speed is more than 239 rps at 180V driving voltage.