it is to be understood that the figures are schematic and do not necessarily show the various aspects of the embodiments of the present invention to scale . references to features being relative to another feature or the like are not intended to be limiting and are for ease of understanding . for example references to anything being ‘ proximal ’ or ‘ distal ’ are not intended to be limiting except insofar as they describe the relationships between various aspects of the embodiments . in the present specification , proximal is used to describe anything that is at the end closest to the practitioner carrying out the procedure and distal is used to describe anything that is at the end furthest from the practitioner carrying out the procedure . fig1 schematically illustrates a release mechanism 10 in accordance with the present invention . the mechanism comprises an elongate shaft 12 having an inner lumen 14 passing through it . an actuating member such as a wire 18 can pass through the lumen and be positioned to maintain the mechanism 10 in its closed configuration ( as shown ) and can be retracted from this interlocking position to a releasing position to enable the mechanism 10 to release a medical device as discussed below . integrally formed with the shaft 12 , by cutting suitable shapes from the shaft 12 , are a pair of arms 20 , 30 . in this example the arms 20 , 30 and shaft 12 are formed from the same flexible tube by laser cutting suitable shapes from the tube along cut line 16 . fig1 shows the front side of the mechanism 10 and the rear side of the mechanism has the same cut line 16 , as can be appreciated from fig2 to 4 that show the mechanism 10 of fig1 in cross - section . the cut or slit 16 allows the arms 20 , 30 to open such that gripping portions 42 , 43 at the distal ends of the arms 20 , 30 ( which in this example are also laser cut from the same tube ) open to release a medical device ( not shown ). the arms 20 , 30 are mutually opposed and are substantially parallel when in this closed configuration as can be seen in fig1 . though not depicted , the arms are biased to open and when free to do so will separate away from each other , opening up the gripping portions 42 , 43 . each arm 20 , 30 has a respective interlocking member 23 , 33 and a respective connecting member 25 , 35 . these are each formed by the cutting the tube and are interposed with each other to form a very compact and low profile mechanism 10 . as can be seen in fig2 , the upper arm 20 has a connecting portion 25 located at section 2 - 2 , above and interposed between the outermost tips of the interconnecting member 23 of the lower arm 30 . the connecting portion 25 connects the interlocking member 23 of the upper arm 20 to the shaft portion 12 and the connecting portion 35 of the lower arm 30 connects the interlocking member 33 to the gripping portion 43 of the lower arm 30 . each connecting portion 25 , 35 opposes the interlocking member 33 , 23 of the other arm 30 , 20 and defines a recess into which the interlocking member 33 , 23 is received . as can be seen from fig2 , at this section along the length of the mechanism 10 , the interlocking member 33 of the lower arm 30 forms more than half of the inner shaft lumen 14 . when an actuating member ( not shown ), such as a wire , is received in the lumen 14 , movement of the lower arm 30 in the direction of its bias ( i . e . downwards in fig1 to 4 ) is prevented because the interlocking member 33 surrounds more than half of the wire and the spacing between the end portions of the interlocking member 33 is too small for the wire to pass through ( and there is insufficient flexibility in the end portions of the interlocking member 33 to allow them to be deflected apart for the wire to pass through them ). thus downward movement of the lower arm 30 is prevented for as long as the wire is in place in the lumen 14 , by this section of the mechanism 10 . similarly , and as can be seen from fig3 , at this section along the length of the mechanism 10 , the interlocking member 23 of the upper arm 20 forms more than half of the inner shaft lumen 14 . when the wire is received in the lumen 14 , movement of the upper arm 20 in the direction of its bias ( i . e . upwards in fig1 to 4 ) is prevented because the interlocking member 23 surrounds more than half of the wire and the spacing between the ends of the interlocking member 23 is too small for the wire to pass through ( and there is insufficient flexibility in the ends of the interlocking member 23 to allow them to be deflected apart for the wire to pass through them ). thus upward movement of the upper arm 20 is prevented for as long as the wire is in place in the lumen 14 , by this section of the mechanism 10 . as shown in fig4 , at this section along the mechanism 10 , the arms are substantially the same and are mirror images of each other and neither arm 20 , sufficiently encircles the wire to prevent movement of the arm 20 , 30 in the direction of its bias . therefore each arm 20 , 30 is prevented at a particular section along the mechanism 10 from opening by the interaction of the interlocking portion 23 , 33 of the arm 20 , 30 with the wire . the upper arm 20 interlocking portion 23 interacts with the wire at one location along the length of the mechanism 10 and the lower arm 30 interlocking portion 22 interacts with the wire at another , longitudinally spaced location along the length of the mechanism 10 , enabling the mechanism 10 to be formed from a single strip of tubular material and providing a compact and low profile mechanism 10 . once the wire is removed , it can readily be seen from fig2 and 4 that the arms 20 , 30 are free to move apart under their bias . fig5 illustrates an alternative release mechanism 10 in accordance with the present invention . the mechanism comprises an elongate shaft 12 having an inner lumen 14 passing through it , the same as the arrangement of fig1 . indeed the release mechanism 10 of fig5 is the same as the release mechanism of fig1 but the interlocking members of the fig5 arrangement are further provided with arcuate strips 26 , 36 . these strips 26 , 36 are also integrally formed with the shaft 12 , by cutting a pair of circumferential strips 22 , 24 from the interlocking member 23 of the first arm 20 and a pair of circumferential strips 32 , 34 from the interlocking member 33 of the second arm 30 . the slits 22 , 24 , 32 , 34 of each pair are substantially parallel to each other and are substantially perpendicular to the longitudinal axis of the elongate shaft 12 . in the example shown in fig5 , the slits 22 , 24 , 32 , 34 when viewed from the end of the mechanism 10 have a substantially semi - circular or arcuate shape , although they may cover more or less of the surface of each arm 20 , 30 in other arrangements . the slits 22 , 24 , 32 , 34 define the deflectable strips 26 , 36 of the interlocking members 23 , 33 of the arms 20 , 30 . each deflectable strip 26 , 36 is pushed inwardly ( i . e . in the direction towards the opposing arm 20 , 30 and towards the centre of the lumen 14 ). the strips 26 , 36 are shown fully deflected in fig5 to 7 , with the strip 36 of the second arm 30 being seen in fig6 and the strip 26 of the first arm 20 being seen in fig7 . in this arrangement , once deflected the strips 26 , 36 remain in their inwardly deflected position even after removing the pressing force . the deflected strips 26 , 36 partially define an actuator lumen 50 , which can be seen in the arrangement of fig8 and 9 ( to which the arrangement of fig5 to 7 is similar ). the actuator lumen 50 is within the inner shaft lumen 14 that extends along the length of the mechanism 10 . the strips 26 , 36 clearly only define parts of the walls of the lumen 50 , with an upper partial wall segment being defined by the upper strip 26 and a lower partial wall segment being defined by the lower strip 36 . however these partial segments are sufficient for an actuating member 18 ( not shown ) when introduced into the actuator lumen 50 to abut against the strips 26 , 36 ( under the biasing of the arms 20 , 30 ) and to oppose their opening . in other words , upper arm 20 is biased upwardly but is prevented from moving upward by abutment of the upper strip 26 on the underside of the actuating member 18 and lower arm 30 is biased downwardly but is prevented from moving downward by abutment of the lower strip 36 on the topside of the actuating member 18 . the actuating member 18 obstructs and prevents movement of the strips 26 , 36 of the interlocking members 23 , 33 thus preventing movement of the arms 20 , 30 and likewise preventing the gripping portions 42 , 43 opening to release a device held between them . as best seen in fig8 and 9 , which show a mechanism 10 similar to the schematically shown mechanism of fig5 to 7 , gripping portions 42 , 43 of the arms 20 , 30 at least partially define a hollow spherical space 44 and an opening orifice 46 for holding an object to be released . in particular , this arrangement is suitable for holding an embolic coil ( not shown ) having an enlarged head portion at its proximal end , typically a ball . the ball is held in the spherical space 44 and the orifice 46 , through which the coil protrudes from the mechanism 10 , is too small for the ball to pass through . however when the actuating member ( not shown in this figure ) is moved to its releasing position the strips 26 , 36 are released and the biased open arms 20 , 30 open and thus also enlarge the orifice 46 and release the ball from the spherical space 44 . the medical device is thus deployed . as can be seen in fig9 , this mechanism 10 is particularly suited to use for procedures where space and size are constrained , as the profile of the mechanism 10 is defined by the diameter d of the shaft portion 12 . whilst the arrangement of fig5 to 7 and 8 and 9 illustrate mechanisms 10 having interlocking members 23 , 33 that surround more than half of the wire at portions along the length of the mechanism 10 ( as also in accordance with fig1 to 4 ) and additionally strips 26 , 36 , it is within the scope of the invention for the interlocking members 23 , 33 to comprise just the strips 26 , 36 and it is not necessary for the interlocking members 23 , 33 to also surround more than half of the wire if the strips 26 , 36 are present .
the disclosure provides a release mechanism , method of manufacturing , and method of releasing a medical device . the mechanism comprises a generally elongate shaft , an actuating member receivable in the elongate shaft , the actuating member having an interlocking position and a releasing position , and at least two opposed arms at a distal end of the elongate shaft , biased to open relative to each other , each arm comprising a gripping portion at a distal end , and at least one interlocking member . the gripping portions of the arms may define a hollow space for holding a device . the interlocking member of each arm is longitudinally spaced from the interlocking member of any other arm and extends circumferentially around the actuating member . the actuating member is longitudinally retractable from the interlocking position to the releasing position to enable the arms to open for releasing a medical device from the gripping portions .