A novel design, material, and fabrication method are presented to fabricate a passive micro-ball valve. Microvalves are critical components in microflow control devices used to control the fluid flows in microchannels. These microflow control devices can be integrated with microsensors to form micro analysis systems. Glass/silicon-based fabrication is complicated and expensive. Therefore, other materials and fabrication methods have been proposed. In this research, Melinex 453, a polyester film, and pressure sensitive adhesives were used to fabricate a micro-ball valve by a microlamination method. The valve was designed to have a 450 μm diameter glass ball floating inside a chamber size of 800 μm. The ball will permit flow in the forward direction and impede flow in the reverse direction. The fabrication method consists of three steps: patterning, registration and bonding. The patterning step was accomplished using laser micromachining. Registration and bonding were performed with the use of a pin-alignment fixture. Pressure sensitive adhesive was used in the bonding step using double-sided acrylic adhesive tape. The micro-ball valve has advantages over other microvalves in terms of little dead volume, simple design, disposability, low operating pressure in forward direction, and low leakage in reverse direction. The micro-bal1 valve was characterized by pressure drop testing at different flow rates from 1 to 7.5 ml/min. The experimental results tend to agree with a simple theoretical model of the pressure drop through an orifice. Moreover, an average pressure drop diodicity of at least 2980 has been achieved. / Graduation date: 2002