Abstract: A noninvasive method and apparatus for withdrawing fluid from an organism and determining the concentration of a substance in the fluid is disclosed. The noninvasive apparatus comprises a substance concentration sensor (120) that includes an extraction transducer (126) and a substance sensing transducer (133). The extraction transducer includes a container (123); a planar piezoelectric (ultrasonic) transducer (124); a focusing lens (125); and a backing layer (127). The container includes a flange (129) that is attached to the skin of an organism by an adhesive film seal (131). The focusing lens (125) is a plano-concave shape such that the concave side faces the skin of the organism. Thus, the focusing lens (125) defines a cavity (135). Located in the cavity (135) is the substance sensing transducer (133). Positioned above the focusing lens is the ultrasonic transducer (124). A pulse generator (121) is connected to and drives the ultrasonic transducer.
Abstract: Ultrasonic energy is used to release a stored drug and forcibly move the drug through the skin of an organism into the blood stream. A housing (81) includes a cavity (67) defined by an assembly of ultrasonic transducers (65) and separated from the skin by a polymeric membrane (69) that stores the drug to be delivered. The ultrasonic transducer assembly includes a flat, circular ultrasonic transducer (85) that defines the top of a truncated cone and a plurality of transducer segments (87a, 87b, 87c, 87d . . . ) that define the walls of the cone. The resonant frequency of the planar transducer is lower than the resonant frequency of the transducer segments. The planar, flat, circular transducer generates fixed frequency (5 KHz-1 MHz range) ultrasonic stimuli impulses for a predetermined period of time (10-20 seconds). Between the stimuli pulse periods, the transducer segments receive variable frequency ultrasonic pumping pulses.