IMPEDANCE SENSOR

摘要

A transdermal transport device includes a reservoir for holding a formulation of an active principle, a needle (14) with a bore through which the formulation is transported between the reservoir and a target area of a biological body, and an impedance sensor(32). The impedance sensor has an electrode positioned to measure the impedance of a portion of the target area between the needle and the electrode to indicate the depth of penetration of the needle into the target area.