Abstract: Multielement ultrasonic probe production process connecting a piezoelectric ceramic block incorporating an upper conductive layer and a lower layer to two printed circuits having a metallized face and a face provided with conductive strips, electrically connecting one of the conductive strips to one of the faces of the printed circuits and the other conductive strip to the other face of said circuits, cutting out said block and the upper part of said circuits so as to form equidistant piezoelectric elements and mechanically insulating them from one another, as well as the connections with respect to each element.The invention has application to medical echography.

Abstract: An echography device with dynamic focusing and sectorial scanning, comprising a transmitting portion (16) and a receiving portion (18) constituting piezoelectric transducers (4), juxtaposed in a form of a linear bar (2), each transducer (4) being associated with a delay line (26,32), the delays applied when a wave is being received being determined as a function of a reference dependent on the delays when the wave is being retransmitted and stored in a digital memory (34), the said reference being fed into a frequency adjustable oscillator (42) associated with a servo-device (38, 56, 54) through a computer.

Abstract: Process for producing complex ultrasonic transducers comprising cutting out a piezoelectric ceramic block along lines which are parallel to one another by means of at least two rows of channels making it possible to produce elementary transducers and selecting the cut elements so as to obtain the desired complex transducer shape, wherein the selected elements are electrically interconnected by one of their faces by means of a conductive deposit and the other face of said elements is raised to reference potential.Application to the production of ring grating or annular transducers.

Abstract: The device for studying vascular behavior particularly in a lower limb of a patient comprises pressure applying means for causing occlusion of the limb under study, means for controlling the characteristics of progressive variation in the pressure applied by the pressure-applying means as a function of time during occlusion of the limb under study, a plethysmograph for delivering signals which are representative of an electrical impedance related to the limb under study and of variations in such electrical impedance, and means for determining, from coefficients of standardization which are characteristic of the healthy vascular operation of a normal limb of the same type as the limb under study and from the signals, indices which are representative of the vascular behavior of the limb under study.

Abstract: In order to excite living cells, a FM transmitter transmits for a period t at a frequency f such that the difference between f and a reference frequency f.sub.O sets the amplitude of a desired nerve stimulation pulse. A receiver implanted in the living body is inductively coupled to the transmitter and processes the signal so as to obtain an output signal having an amplitude which is proportional to the frequency deviation. The duration of the stimulation pulse is adjustable independently of the amplitude. The output signal is applied between two electrodes which are implanted in the vicinity of the cells to be excited and can be multiplexed to excite several pairs of electrodes in succession by an electronic circuit advanced by signal segments at a frequency at one end of the deviation range.