A fluid delivery device for transdermal delivery of a fluid to a patient. The device comprises an envelope that may be applied to a patient's skin. The envelope comprises at least one diffusion layer coupled to at least one impermeable layer such that at least a chamber is defined therebetween. Other embodiments include internal diffusion layers, and thus possess additional chambers, as well. In one arrangement, an adhesive boundary layer 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 is provided to inhibit the growth of microorganisms.