Disposable infusion device

A disposable device is provided which accurately and reliably delivers an infusable liquid to a patient. The infusion device includes a housing which defines a bladder chamber. A compressible bladder is disposed in the bladder chamber and is compressed by the housing upon filling the bladder with an infusable liquid to create a pressurized bladder. The infusion devices further includes a delivery system for subcutaneously delivering the infusable liquid to a body. The delivery system includes a collapsible member that supports an injection needle and a cannula. The injection needle is used to insert the cannula into the skin of the body being treated. The cannula is in communication with the bladder during delivery of the infusable liquid. The housing includes microfluidic passageways that allow communication between fluid in the bladder and the cannula.