A drug delivery device includes a housing with at least one pressure communication channel or aperture, which distributes a negative fluid pressure across its base to draw tissue against the device. The device can also include a porous, adhesive layer over the channel(s) or aperture(s), for attaching to tissue. The device can also include a pressure sensor for determining whether there is proper attachment. Further, a bladder may be used instead of the adhesive layer for attaching the device. The bladder, in a partially inflated state, can apply constant pressure across a contact surface causing a flexible adhesive layer attached to the bladder to confirm and adhere to the tissue. Subsequent evacuation of the bladder causes it to deflate and collapse or retract, thereby causing the flexible adhesive layer to pull and stretch the tissue toward the base.