Microphones have advanced tremendously since Thomas Edison patented a device in 1877 based on the resistance of carbon granules. The most commonly used microphone today is the foil electret microphone, which was developed in the 1960s, and enabled microphones to be easily incorporated into a multitude of products. It appears that a new breakthrough in microphone technology may be imminent: the MEMS microphone. MEMS, an acronym for microelectromechanical systems, refers to any small mechanical device that can be fabricated on a silicon chip, often connected to some form of electrical system. A MEMS microphone can be very small (less than 1 mm) and can be incorporated directly onto an electronic chip.