A PZT Insulin Pump Integrated with a Silicon Micro Needle Array for Transdermal Drug Delivery

Abstract

Many of the compounds in drugs cannot be effectively delivered using current drug delivery techniques (e.g., pills and injections). Transdermal delivery is an attractive alternative, but it is limited by the extremely low permeability of the skin. Because the primary barrier to transport is located in the upper tissue, micro-electro-mechanical-system (MEMS) technology provides novel means in terms of both micro needles array and PZT pump, with the former one to increase permeability of human skin with efficiency, safety and painless delivery, and the latter one to decrease the size of the pump. Micro needles array has many advantages, including minimal trauma at penetration site due to the small size in needle, no condition limit, painless drug delivery for penetration depth with few nerves, and precise control of penetration depth for micro needle extension length. The micro needles array drug delivery is precise, painless, effective, clean and neatness, without any inconvenience. This promotes the development of biomedical sciences and technology and makes medical devices more humanized. So far most of the insulin pump has been using mechanical pump in clinical practices. We present the first development of this novel technology which can assemble the PZT pump and the micro needles together for diabetes mellitus. The micro needle array based on a flexible substrate can be mounted on non-planar surface or even on flexible objects such as a human fingers and arms. The PZT pump can pump the precision insulin much more accurately than the mechanical pump and the overall size is much smaller than those mechanical pumps. The hollow wall straight micro needles array is fabricated on a flexible substrate by deep-reactive ion etching (DRIE) and anisotropic wet etching techniques. The fabricated hollow micro needles are 200/spl mu/m in length and 30/spl mu/m in diameter. The micro needle array, which may be built with on-board fluid pumps, have potential applications in the chemical and biomedical fields for localized chemical analysis, programmable drug-delivery systems, and very small, precise fluids sampling. The micro needles array has been installed in an insulin pump for demonstration and a leak free packaging is introduced.