Micromachining isa technology that miniaturizes mechanical sensors and actuators through the use of tools and materials commonly used in the integrated circuit industry. The physics of the devices formed in this way are sometimes similar and sometimes different to achieve the same functionality of current macroscopic devices, but in sizes that are hundreds or thousands of times smaller. This article will discuss a few chemical detectors being developed as examples of the application of microelectromechanical systems (MEMS) for nonoptical laboratory instruments, Tn this article, we will report on the development and demonstration of two approaches (quadrupole and magnetic Lorentz) to fabricate a mass filter as part of a mass spectrometer. This article is, not meant as a review of the field of MEMS chemical sensors, but rather a tutorial on how miniaturization:ls achievable through the use of MEMS fabrication techniques for mass spectrometers.