Opto-MEMS refers to micro devices that either manipulate light or use it for sensing. Two examples of manipulating Opto-MEMS devices are the WDM and optical switch: The WDM splits information contained in wide band of frequencies into narrow bands for example by using tunable Fabry-Perot interferometer. The micromachined optical switch redirected such light to different optical fibers for example by using tilting micro=mirrors. Applications of optical sensor, on the other hand, can be found for wide range of applications from displacement sensors to chemical sensors. These sensitive sensors are based on the interaction between some physical phenomena (i.e., acceleration, chemical reaction, etc.) And the optical properties of the sensor and can be used to sense extremely minute effects. In some cases MEMS and particular Opto-MEMS do not follow the VLSI paradigm of high yield, repeatedly and mass production, even thought they relay on very similar technologies. This contradiction raises questions as to the commercial value of MEMS and Opto-MEMS. This talk will view the bottlenecks of MEMS with emphasis on Opto-MEMS and will discuss current research aiming to increase the compatibility of Opto- MEMS with conventional VLSI. In addition, examples of optical displacement sensors, and optical switches will be presented.