Intelligent micro-fluidic system for drug delivery

This paper describes the development and characterization of a micro-fluidic system which comprises of a micro-pump, passive micro-valve and its control circuit. Some applications for such a system include micro-coolant systems, micro-chemical analysis systems and fluid handling systems. Micro-fluidic systems are generally application specific and the focus of the proposed system is for drug delivery. The micro-pump is of the reciprocating membrane type and is based on piezoelectric actuation. It can be manufactured using MEMS fabrication technology such as silicon micro-machining. The pump utilizes check valves made of photosensitive polyimide as the rectifying unit and a 10 mm diameter piezoelectric diaphragm as the actuator unit. The theoretical analysis for the actuator and valve characteristics is presented in this paper. The resulting effects on the flow characteristics and performance are also presented. Results obtained from experiments are also described. Based on these characteristics, a controller circuit is designed and fabricated. The controller uses a Single-Chip-Computer as the processor unit. A liquid crystal display (LCD) is used to display the pump status and settings. The driver is powered by dry cells and it can provide a 200 V square wave input for the pump by utilizing a built-in transformer and regulator circuit. There are two modes of control, namely, frequency and voltage driving to control the pump performance characteristics such as flow rate and pump head. For this system, a maximum pump head and pump rate of 3.28 mH₂O and 900 μl/min respectively are obtained.