this invention will be described in connection with the drawings which illustrate our presumably preferred embodiment . fig1 is a perspective view of our flow probe shown in closed position . fig2 is a section taken along broken line 2 -- 2 of fig1 . fig5 is a perspective view of the probe in open position . the lumen is formed of two arcuate parts 2 and 3 ; an arcuate bent coil 4 is encapsulated in part 2 , and a bent coil 5 is encapsulated in part 3 . the electrodes 6 and 7 are mounted in the conventional relation to the magnetic field for a faraday type flow probe . for this purpose , they are mounted within the body of the part 3 below the free end 8 and the end 9 of the part 3 . the end 9 is connected to or formed integrally with a handle 10 which extends at an angle to the chord connecting electrodes 6 and 7 . we prefer to employ a 45 ° angle . for convenience of holding the probe , the handle is joined to a handle part 11 which extends at an obtuse angle to the handle part 10 . the electrical leads 13 connected to the coil 5 are encased by cable sheath 17 &# 39 ; which passes through tube 20 embedded in handle 10 and 11 . a ground electrode 12 may be provided in the part 3 or an external ground connection may be utilized . the leads 15 and 16 connected to the electrodes 6 and 7 are encased by a cable sheath 17 which also passes through tube 20 for connection to suitable readout . the ground electrode is connected to cable sheath 17 and 17 &# 39 ;. the leads 19 connected to the coil 4 are encased by cable sheath 14 . the lumen part 2 is mounted on the slide 23 shaped to form a wedge dovetail with the handle 10 so that it may slide up and down the handle 10 and may be entirely withdrawn from the handle . the slide may be held in a selected position on the handle 10 by the screw 24 which fits in the recess 24b when the lumen is assembled . the screw is adjusted to permit the slide to move . when the screw reaches the recess , it &# 34 ; jumps &# 34 ; into the recess . the screw may be made of flexible material , such as nylon . the screw in the recess acts to lock the lumen in position . as will be seen by sliding the part 23 up the handle , the part moves so as to separate the free ends 8 and 25 , providing an opening which is in direction substantially parallel to the handle 10 and at an acute angle to the line connecting 6 and 7 . the size of the opening is dependent on how far up the handle the slide is moved . the slide and lumen part 2 may be removed completely from the handle . this permits the lumen part 3 to be maneuvered into position under an artery or other vessel . the slide may then be positioned on the handle and slid into position as shown in fig2 . the free ends of the lumen halves are formed with parallel ends 8a and 25a forming an interface between the lumen halves which are interference surfaces . these are entered at an acute angle to the horizontal diameter of the lumen . the pulsation of the artery creates a pressure against the internal surface of the lumen . the arrangement of the surfaces does not permit any substantial relative displacement of the lumen parts and eliminates electrical artifacts which would otherwise occur . the fit of 8a with respect of 25a may be as close as is practically accomplished in manufacture . the device has particular utility where it is used as a periarterial probe . the slide may be moved to open the lumen and may be held in position with one hand . the blood vessel may be inserted without constricting the blood vessel unlike a probe of like diameter which is of the shutter type .
this invention relates to a flow velocity transducer particularly adapted to the determination of blood flow in blood vessels .