Advanced silicon micro sensors for pressure, acceleration, angular rate, infrared radiation and atomic force have been developed based on bulk silicon micromachining. Distortion- free, precise or very small micro-nanostructures enables extremely sensitive and quick response sensors. Packaged, capacitive and integrated sensors were fabricated. Electrostatic force balancing sensors and resonant sensors performed wide dynamic range and high sensitivity respectively. Novel micromachining techniques developed and applied for the sensors were vacuum packaging, distortion-free anodic bonding, deep RIE, XeF2 silicon etching, thickness monitoring during silicon etching, silicon nano-wire growth by electric field evaporation using UHV STM etc.