text: Micromechanical systems have been evolving based on applying microelectronic processing and production techniques for microscopic mechanical systems such as gears, motors, diaphragms and levers. Microscopic mechanical systems have been used as sensors for sensing acceleration, pressure, and chemical composition, and have been used as actuators such as moving mirrors, shutters, and aerodynamic control surfaces. More particularly, micromechanical systems have been proposed for use in fluid control, such as in medical pharmaceuticals, bearing lubricators and miniature space systems. Many types of fluid flow control systems require the use of pumps and valves.
  Micromechanical pumps are miniature versions of standard size pumps which operate by opening and closing valves in an appropriate sequence while changing the volume between the valves to move fluid through the valves. The valves function to obstruct the path of a communicating fluid. For example, a silicon diaphragm is pushed against a silicon orifice to block the communication of fluid through the orifice. Sealing around the orifice to perfect the obstruction is disadvantageously unreliable because the sealing area is relatively very small as compared to macromechanical systems and because minor imperfections in the sealing surface will lead to leak rates which are negligible at the macroscopic level but significant in comparison to the total fluid flow at the microscopic level. Elastomeric materials have been used for improved valve sealing but are difficult to manufacture on a micromechanical seal. The reliability of micromechanical valves is disadvantageously limited by leakage of the valves on a micro scale. Micromechanical valves and pumps also disadvantageously use moving parts to change the volume of the pumps and suffer from long term reliability problems of moving parts. These and other disadvantages are solved or reduced using the invention.