Prototype micropump for insulin administration based on electrochemical bubble formation.

As part of the development of a percutaneous artificial pancreas islet, an insulin injection micropump was fabricated using micromachine techniques. The major components of the device were a thin-film, two-electrode system incorporated in a closed compartment, a silicone rubber diaphragm to separate an electrolyte solution from an insulin solution, a reservoir for insulin and a microneedle attached to the outlet. Hydrogen bubbles were formed on a platinum working electrode when current was applied. This caused the diaphragm to deform and to exert pressure on the insulin solution in the reservoir on the other side of the diaphragm. The injection of insulin was smooth and the injection rate could be controlled by the electrode potential or current. When the insulin solution was injected into streptozotocin-induced diabetic rats, a decrease in plasma glucose level (PGL) was observed which was dependent on the dose of insulin. No substantial difference was observed compared to manual injection.