MEMS-based micropumps in drug delivery and biomedical applications

This paper briefly overviews progress on the development of MEMS-based micropumps and their applications in drug delivery and other iomedical applications such as micrototal analysis systems ( TAS) or lab-on-a-chip and point of care testing systems (POCT). The focus of the eview is to present key features of micropumps such as actuation methods, working principles, construction, fabrication methods, performance arameters and their medical applications. Micropumps have been categorized as mechanical or non-mechanical based on the method by which ctuation energy is obtained to drive fluid flow. The survey attempts to provide a comprehensive reference for researchers working on design nd development of MEMS-based micropumps and a source for those outside the field who wish to select the best available micropump for a pecific drug delivery or biomedical application. Micropumps for transdermal insulin delivery, artificial sphincter prosthesis, antithrombogenic icropumps for blood transportation, micropump for injection of glucose for diabetes patients and administration of neurotransmitters to neurons nd micropumps for chemical and biological sensing have been reported. Various performance parameters such as flow rate, pressure generated nd size of the micropump have been compared to facilitate selection of appropriate micropump for a particular application. Electrowetting, lectrochemical and ion conductive polymer film (ICPF) actuator micropumps appear to be the most promising ones which provide adequate flow ates at very low applied voltage. Electroosmotic micropumps consume high voltages but exhibit high pressures and are intended for applications here compactness in terms of small size is required along with high-pressure generation. Bimetallic and electrostatic micropumps are smaller n size but exhibit high self-pumping frequency and further research on their design could improve their performance. Micropumps based on iezoelectric actuation require relatively high-applied voltage but exhibit high flow rates and have grown to be the dominant type of micropumps n drug delivery systems and other biomedical applications. Although a lot of progress has been made in micropump research and performance of icropumps has been continuously increasing, there is still a need to incorporate various categories of micropumps in practical drug delivery and iomedical devices and this will continue to provide a substantial stimulus for micropump research and development in future. 2007 Elsevier B.V. All rights reserved.