Electronic MEMS for triggered delivery Amy C. Richards Grayson 1 , Rebecca Scheidt Shawgo, Yawen Li, Michael J. Cima * Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, 12-011, Cambridge, MA 02139, USA Received 20 December 2002; accepted 20 July 2003 Abstract Implantable electronic devices such as pacemakers and neural implants are often used for electrical stimulation. The usage of microfabrication techniques to produce microelectromechanical systems (MEMS) has allowed engineers to address a wider range of clinical indications. A new direction in the area of MEMS technology is the goal of achieving pulsatile drug delivery. The digital capabilities of MEMS may allow greater temporal control over drug release compared to traditional polymer-based systems, while the batch-processing techniques used in the microelectronics industry can lead to greater device uniformity and reproducibility than is currently available to the pharmaceutical industry. A repertoire of structures, including microreservoirs, micropumps, valves, and sensors, is being developed that will provide a strong foundation for the design of integrated, responsive MEMS for drug delivery. D 2003 Published by Elsevier B.V. Keywords: MEMS; BioMEMS; Implant; Implantable; Electronic; Drug delivery; Triggered; Microchip Contents 1. Introduction ..................................................... 174 2. Implantable microelectromechanical systems ...................................... 174 2.1. Neural implants ................................................ 174 2.2. Retinal implants ................................................ 175 2.3. Microneedles ................................................. 176 2.4. Drug-coated stents ............................................... 176 3. MEMS components for drug delivery ......................................... 177 3.1. Microreservoirs ................................................ 177 3.2. Mini- and micropumps ............................................. 177 3.3. Valves .................................................... 178 3.4. Sensors .................................................... 179 4. Silicon MEMS for drug delivery ............................................ 180 5. Conclusions ..................................................... 180 References ......................................................... 181 0169-409X/$ - see front matter D 2003 Published by Elsevier B.V. doi:10.1016/j.addr.2003.07.012 * Corresponding author. Tel.: +1-617-253-6877; fax: +1-617-258-6936. E-mail address: mjcima@mit.edu (M.J. Cima). 1 Current address: School of Chemical and Biomolecular Engineering and the Biomedical Engineering Program, 120 Olin Hall, Cornell University, Ithaca, NY 14853. www.elsevier.com/locate/addr Advanced Drug Delivery Reviews 56 (2004) 173 – 184