A fluid delivery device for transdermal delivery of a fluid to a patient. The device comprises an envelope that may be applied to a patients skin. The envelope comprises at least one diffusion layer (20) coupled to at least one impermeable layer (18) such that at least a chamber (22) is defined therebetween. Other embodiments include internal diffusion layers (42), and thus possess additional chambers, as well. In one arrangement, a boundary layer (200) permits the device to be removably secured to a patient and inhibits radial migration of fluid beyond the periphery of the device. In another arrangement, preferably, an anti-microbial layer (330) is provided to inhibit the growth of microorganisms.
