A new type of flow controller for medical injection was developed and evaluated. The flow rate was controlled by simultaneously varying the friction length and depth of the micro-channel such that the relation between the flow rate and the length of the channel becomes more linear. The micro-channel was fabricated using ultra-precision machining technology. A seal made of butyl rubber was used to stop fluid leakage. The butyl rubber was coated with silicone oil to make the controller rotate smoothly. The flow controller was validated by comparing experimental data with theoretical predictions. Good agreement was found between theory and experiment. (C) 2004 Elsevier Ltd. All rights reserved.