Abstract: An inexpensive disposable plastic flow body interchangeably flow connects in line a conduit flowing fluid, and also, concurrently, acoustically connects to one or more ultrasonic transducers, so as to serve as an acoustic chamber for use with an ultrasonic flowmeter in the measurement of fluid flow velocity and/or volume. The flow connection is preferably accomplished by plugging, preferably by inserting nozzles into surgical tubing. The external ultrasonic transducer(s) is (are) normally connected under pressured contact, typically under spring forces which are preferably of external origin. Acoustic-coupling elements in the walls of the acoustic chamber serve to match the acoustic impedance of the flow body to acoustic impedance of blood. The disposable plug-connected flow body is particularly safe, sterile and convenient for extracorporeal ultrasonic blood flow measurement.

Abstract: Multiple, typically four, acoustic transducers of a time delay acoustic flowmeter are arrayed in a X-cross, crisscross, folded geometry so as to establish a lengthy multiple-leg, typically a two-leg, acoustic path within a compact volume. An ultrasonic signal is transmitted from a transducer A to a transducer B, then electrically amplified and applied to a transducer C which retransmits the ultrasonic signal to a transducer D. The compact transducer configuration is particularly suitable for use during in-vivo blood flow measurement. The acoustic signal is maintained in amplitude from one leg to the next by amplification as an electrical signal.

Abstract: In an acoustic flowmeter of the transit time or Doppler type the electro/acoustic, and/or acousto/electric, gain of one or more elongate acoustic transducers is varied spatially along the length of the transducer. When the transducer(s) are situated across the width of a lumen that is both flowing fluid and surrounded by material that attenuates sound differently that does the fluid during acoustic fluid flow measurement, the differing transducer(s') gain(s) serves to compensate for differing acoustic attenuations in different acoustic paths. Particularly during in-vivo acoustic blood flow measurement, the non-uniform acoustic gain(s) serves to compensate for the differing acoustic attenuations of blood and tissue, commonly fat, surrounding a blood vessel, and to produce a more accurate measurement of blood flow.