BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to intravascular assemblies, and more specifically to a one-piece introducer needle and method of making the needle. 
     2. Background 
     Intravascular devices such as catheter assemblies are generally used for passing fluids between a device such as a syringe or a drip to or from body lumens such as veins or arteries, or other internal target sites. Such an assembly usually includes a hub, and a catheter tube. The tube is typically secured to the hub by means of an eyelet ring that is press fit within the nose of the hub. This hub and tube assembly is then mounted over an introducer needle comprising a sharp needle attached to a plastic hub. The sharp tip of the needle, protruding from the catheter tip, is used for piercing a body lumen so that access may be gained into the body lumen by the needle and subsequently the catheter. Once the catheter and the needle are located within the body lumen, the introducer needle is removed and discarded while the catheter tube remains in the body lumen. A syringe or a tube of a drip is then attached to the hub so that fluids may be passed through the hub and the catheter from the drip or the syringe to the body lumen. The hub is typically made of materials that provide sufficient rigidity thereto and the catheter tube is usually made of a material which is flexible. 
     Intravenous introducer needles with a surface groove are known in the art. One purpose of intravenous introducer needles is to allow a healthcare worker to be able to quickly observe when back-flow of blood enters a surface groove indicating that the needle has penetrated the vein. 
     Introducer hollow needles are conventionally made, one at a time, by a multistep process involving considerable time, labor, and precision machinary. For example, stainless steel hollow wire is straightened, cut to the desired length, tapered, and treated with a variety of finishing steps. There are additional disadvantages to introducer needles such as those described in U.S. Pat. No. 5,279,572, issued to Hokam (“Hokam”), and European Patent No. EPO 893 137 A2, issued to Terumo Kabushiki Kaisha. For instance, Hokam comprises an intravenous introducer needle having two blood back-flow passage routes in which the needle comprises a material that is made of steel. The needle and the handle are manufactured separately through a machining operation and thereafter are fastened together. By requiring that a stainless steel needle be joined to a needle base, an assembling cost is incurred. It is therefore desirable to have a method of fabricating a one-piece needle that is able to reduce the operational cost such as machining of the needle and handle, and the cost of assembling these elements. 
     SUMMARY 
     A method is disclosed for forming a one-piece introducer needle having a head. The method comprises introducing a photoresist material onto a substrate. The temperature of the substrate is increased and then cooled. A photomask is then deposited onto the substrate. The substrate is then exposed to light. A one-piece needle is formed from this process. Additional features, embodiments, and benefits will be evident in view of the figures and detailed description presented herein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
     FIG. 1 illustrates a substrate in accordance with one embodiment of the invention. 
     FIG. 2 illustrates the substrate as in FIG. 1, in which a photoresist is introduced onto the substrate in accordance with one embodiment of the invention. 
     FIG. 3 illustrates the same substrate as in FIG. 2 in which a photomask has been introduced over the photoresist in accordance with one embodiment of the invention. 
     FIG. 4 illustrates the same substrate as in FIG. 3 in which the substrate is exposed to light in accordance with one embodiment of the invention. 
     FIG. 5 illustrates a one-piece needle formed after unnecessary material has been removed from the substrate shown in FIG. 4 in accordance with one embodiment of the invention. 
     FIG. 6 illustrates a plurality of a one-piece needle in accordance with one embodiment of the invention. 
     FIG. 7 illustrates a one-piece needle inserted into a catheter and hub in accordance with one embodiment of the invention. 
     FIG. 8 illustrates a one-piece needle inserted into a catheter and hub in accordance with an embodiment of the invention. 
     FIG. 9 illustrates an isometric view of blood entering a surface groove of a solid tip-surface grooved needle in accordance with one embodiment of the invention. 
     FIG. 10 illustrates an isometric view of blood entering a surface groove of a solid tip-surface grooved needle inserted into a catheter tube in accordance with one embodiment of the invention. 
     FIG. 11 illustrates a top view of blood entering a surface groove of a solid tip-surface grooved needle in accordance with one embodiment of the invention. 
     FIG. 12 illustrates an isometric view of blood entering a surface groove of a solid tip needle in accordance with one embodiment of the invention. 
     FIG. 13 illustrates a top view of blood entering a surface groove of a solid tip needle in accordance with one embodiment of the invention. 
     FIG. 14 illustrates a one-piece needle that has a needle head that is substantially rectangular. 
     FIG. 15 illustrates a one-piece needle inserted into a catheter and hub in accordance with one embodiment of the invention. 
     FIG. 16 illustrates a one-piece spiral needle in accordance with one embodiment of the invention. 
     FIG. 17 illustrates the one-piece spiral needle inserted into a catheter and hub in accordance with one embodiment of the invention. 
     FIG. 18 illustrates a one-piece needle having a substantially rectangular head of in accordance with one embodiment of the invention. 
     FIG. 19 illustrates the one-piece needle of FIG. 18 inserted into a catheter and hub in accordance with one embodiment of the invention. 
     FIG. 20 illustrates a one-piece needle having a substantially cylindrical or substantially square head in accordance with one embodiment of the invention. 
     FIG. 21 illustrates the one-piece needle of FIG. 20 inserted into a catheter and hub in accordance with one embodiment of the invention. 
     FIG. 22 illustrates a one-piece needle having a substantially looped head in accordance with one embodiment of the invention. 
     FIG. 23 illustrates a one-piece needle inserted into a catheter and hub in accordance with one embodiment of the invention. 
     FIG. 24 illustrates a cross-section of a solid tip needle with a surface groove in accordance with one embodiment of the invention. 
     FIG. 25 illustrates a cross-section of a solid tip needle with a rectangular shaped surface groove in accordance with one embodiment of the invention. 
     FIG. 26 illustrates a cross-section of a solid tip needle with a v-shape surface groove in accordance with one embodiment of the invention. 
     FIG. 27 illustrates a cross-section of a solid tip needle with a surface groove having a half circle shape in accordance with one embodiment of the invention. 
     FIG. 28 illustrates a cross-section of a solid tip needle with a plurality of surface grooves having a half circle shape in accordance with one embodiment of the invention. 
     FIG. 29 illustrates a cross-section of a solid tip needle with a plurality of surface grooves having a substantially v-shape in accordance with one embodiment of the invention. 
    
    
     DETAILED DESCRIPTION 
     One embodiment of the invention relates to forming a one-piece introducer needle for use in an intravascular assembly by a photolithography process. Photolithography is a process that involves creating in and on the substrate surface dimensions that are close to the design dimensions. Photolithography also involves the correct alignment of the pattern onto the surface of the substrate. 
     Another embodiment of the invention relates to the formation of a beveled sharp end of the distal tip of the needle. Another embodiment of the invention relates to forming a single piece introducer needle with a groove. 
     Referring to the figures, exemplary embodiments of the invention will now be described. The exemplary embodiments are provided to illustrate aspects of the invention and should not be construed as limiting the scope of the invention. 
     FIGS. 1-6 illustrate one embodiment of the invention using a method related to photolithography to form a one-piece needle. FIG. 1 illustrates a substrate that may include a metal or other materials such as polymer or ceramic material. If metal is used as a substrate, the metal sheet should have a tensile strength of at least about 300,000 psi, a Rockwell C hardness of at least about 40-45, and ductility so that the needle may not be bent. The metals that may be used include stainless steel such as a stainless steel 410, Gin  5 , Gin  6  razorblade grade stainless steel, and molybdenum. The thickness of the steel may be about 0.0250 inches or less. 
     FIG. 2 illustrates photoresist  110  introduced over substrate  100  in accordance with one embodiment of the invention. Photoresist  110  is a light sensitive material. Exposure to light causes changes to its structure and properties. Either a positive-acting photoresist or a negative-acting photoresist may be used. A positive-acting photoresist when exposed to light, changes the chemical structure from a relatively nonsoluble condition to a more soluble condition which is referred to as photosolubilization. A negative-acting photoresist, on the other hand, when exposed to light is changed from a soluble condition to an insoluble condition which is referred to as polymerization. A negative-acting photoresist outlines the portion outside of the one-piece needle that is to be removed. In contrast, a positive-acting photoresist outlines the one-piece needle itself. For purposes of illustration only, a negative photoresist is used to represent photoresist  110 . 
     Photoresist  110  may include negative photoresists such as KMER or RISTON that are commercially available from DuPont located in Wilmington, Del. Photoresist  110  and substrate  100  is then baked at a moderately elevated temperature for several minutes such as at about 70° C. to 90° C. for approximately 10 minutes to dry the coating. Other temperatures may be used. The temperature used depends upon the photoresist used and the amount of photoresist applied to substrate  100 . After substrate  100  and photoresist  110  have been allowed to cool for a certain amount of time such as about five minutes. A photomask having a negative image of the plurality of the one-piece needles to be fabricated is positioned over the coated top surface of the substrate  100 . Substrate  100  and photoresist  110  are then exposed to light in the image of a plurality of one-piece needles as illustrated in FIG.  7 . The plurality of one-piece needles include a variety of shapes such as that which is shown in FIGS. 7,  14 ,  16 ,  18 ,  20 ,  22 , or any other suitable shape. 
     FIG. 3 illustrates a first photomask  120  introduced over photoresist  110 . Photoresist  110  may be deposited over substrate  100  using a variety of methods such as by using a screen over substrate  100  and spraying photoresist  110  over substrate  100  or any other suitable method. First photomask  120  includes suitable commercially available photomasks. First photomask  120  covers photoresist  110  such that an outline of a needle is formed as shown in FIG.  3 . 
     FIG. 4 illustrates substrate  100  having undergone exposure to light. The light source that is used to expose photoresist  110  to light may be ultraviolet radiation, a carbon-arc light, mercury-vapor lamps, ultraviolet rich fluorescent lights or any other suitable light. Substrate  100  is exposed to the light from a couple seconds to several minutes depending upon the nature and the power of the light source, the distance of the light from the photoresist  110 , and the sensitivity of the photoresist  110  that is chosen. FIG. 4 illustrates a one-piece needle of a plurality of one-piece needles formed from substrate  100 . After exposure to the light, the photoresist  110  is rinsed in a suitable solution such as any one of several commercially available developers to remove the unexposed photoresist  112 . Thereafter, FIG. 5 illustrates a single one-piece needle formed from the substrate. FIG. 6 illustrates a plurality of one-piece needles formed from the sheet of metal that was used as a substrate for the formation of a plurality of needles. After rinsing, the sheet of metal with the photoresist  110  in the form of intravenous needles, may be baked at, for example, 120° C. to 260° C. for 3 to 12 minutes to further harden the remaining photoresist  110 . 
     The next operation is to etch away the unnecessary metal in an etching process. The metal may be etched using an etching solution, plasma or any other suitable etching process. Typical etching solutions include 36-40° Baumé aqueous ferric chloride, an aqueous mixture of ferric chloride and hydrochloric acid, or a mixture of aqueous hydrochloric acid and nitric acid, or other suitable material. These etching solutions, etching processes, and the photoetching process are known in the art. 
     After the etching step, the plurality of one-piece needles are removed from the etching solution. The plurality of needles are then washed and dried. Each needle is separated from the plurality of needles formed. The process described in FIGS. 1-6 is then repeated to form another sheet of one-piece needles. It will be appreciated that the process described in FIGS. 1-6 may be repeated to the other side of substrate  100 . This allows for creative designs of one-piece needles such as the one-piece needles shown in FIGS. 14,  16 ,  18 , and  22 . 
     The type of designs of one-piece needles that may be formed from this process is limited only by the creativity of the manufacturer. It will be appreciated that the process described in FIGS. 1-5 are used to form the different designs that are presented below. 
     FIG. 7 illustrates one-piece needle  10  comprises a head in the shape of a handle  25 , a flange  30  portion of the handle, a tapered portion  35  of handle  25 , a stepped portion  37  of the handle  25 , a needle  40 , wherein the needle portion has a surface groove  60 , and a beveled portion  55  that transitions to a distal sharp tip  50  of needle  40 . Surface groove  60  extends from proximal end  65  of surface groove  60  to the distal end  72  of the groove channel. 
     The dimensions of the one-piece needle that is formed varies with the gauge of the intravascular assembly to be fabricated. In this embodiment, a solid tip needle with a surface groove is formed. The outer diameter of the handle may range from approximately 0.25 inches to 0.35 inches in the proximal portion of the handle. The inner diameter of the proximal portion of handle  25  may range from approximately 0.20 inches to 0.30 inches. The outer diameter of flange  30  may range from approximately 0.50 inches to 0.80 inches. The inner diameter of flange  30  may range from approximately 0.40 inches to 0.60 inches. Tapered portion of handle  25  has an inner and an outer diameter that varies with the tapered portion of a particular needle being formed. However, the range of outer diameters of the tapered portion may range from 0.20 inches to 0.30 inches. Similarly, the inner diameter of the tapered portion may range approximately from 0.15 inches to 0.25 inches. The first stepped portion of handle  25  has an outer diameter that ranges from approximately 0.30 inches to 0.40 inches and the inner diameter ranges from approximately 0.25 inches to 0.35 inches. Second stepped portion of handle  25  has an outer diameter that ranges from 0.25 inches to 0.35 inches and an inner diameter that ranges from approximately 0.20 inches to 0.30 inches, and a length that ranges from approximately 0.25 inches to 0.75 inches. Needle  40  may have a length that ranges from approximately 0.70 inches to 2.5 inches, an outer diameter that ranges from approximately 0.10 inches to 0.02 inches. It will be appreciated that a solid tip needle lacks the inner diameter dimensions listed for the proximal portion of handle  25 , flange  30 , the tapered portion of handle  25 , the first and second stepped portions of handle  25 . 
     In FIG. 7, needle  40  that is formed has a solid tip but a surface groove is formed therein. Surface groove  60  allows blood to enter needle  40  at or near the distal end of needle  40 . The blood moves in the proximal direction of needle  40  as shown in FIG.  7 . It will be appreciated that the surface groove channel in FIG. 7 illustrates that since the surface groove channel is formed on the external portion of the needle, there is no outer diameter for the surface groove channel. The distance from proximal end  65  and distal end  72  of surface groove  60  ranges from approximately 0.25 inches to 2.5 inches. 
     FIG. 8 illustrates the one-piece needle formed from the process shown in FIGS. 1 through 5 inserted into a catheter and hub. It will be appreciated that the one-piece needle tip formed from this process may be either solid or solid with surface groove. The surface groove may have a variety of shapes as illustrated in FIGS. 9 to  13 , and  24 , to  29 . 
     FIGS. 9 through 11 illustrate one embodiment of the invention in which a needle  40  has a solid tip portion and a surface groove  60 . FIGS. 9 and 10 provide isometric views of solid needle  40  and shows the flow of blood passing over the distal tip of needle  40  and entering surface groove  60 . FIG. 10 further illustrates the flow of blood when needle  40  is coupled to a catheter tube  70 . FIG. 11 illustrates a top view of needle  40  wherein blood flows around solid tip needle  40  and enters surface groove  60 . 
     FIGS. 12 and 13 illustrate needle  40  and needle tip with a pointed end inserted into a patient&#39;s vein. The needle tip is a solid sharp. The blood flows into the surface groove and travels to the proximal end of needle  40 . Given the explanation of a surface groove in the one-piece needle, the following description presents a variety of different shaped one-piece needles such as needles having different shaped heads and one-piece needles with and without surface grooves. 
     FIG. 14 illustrates one embodiment of the invention for forming a one-piece needle. The one-piece needle comprises a substantially rectangular portion at the proximal end formed by portions  230 ,  240 , and  250 . Disk portion  220  is located at the proximal end of the one-piece needle. One purpose of disk portion  220  is locking the one-piece needle into a catheter and hub as illustrated in FIG.  15 . The one-piece needle then transitions into a distal portion of one-piece needle  262 . The one-piece needle further comprises a beveled distal tip  210  at the distal end of the one-piece needle. 
     It will be appreciated that the dimension of the one-piece introducer needle that is formed vary with the gauge of the intravascular assembly to be fabricated. For example, the distal portion of one-piece needle  262  may range in length from 0.7 inches to 2.5 inches. Furthermore, disk portion  220  may range in diameter from 0.15 inches to 0.35 inches. This large range is present to accommodate the design of a luer lock feature in the hub. Portion  250  may range from 0.5 inches to 2.0 inches. Portion  240  may range from 0.5 inches to 2.0 inches. Portion  230  may range from 0.5 inches to 2.0 inches. It will be appreciated that the diameter of the needle is the same as that which is described above and is dependent upon the gauge of the intravascular assembly to be fabricated. 
     FIG. 15 illustrates the one-piece needle formed from the process illustrated in FIGS. 1-5 inserted into a catheter and hub  280 . It will be appreciated that the one-piece needle formed from the process illustrated in FIGS. 1-5 is snapped into place at block  285  that has a recessed region for receiving portion  230 . It will also be appreciated that disk portion  220  is locked in place at block  285  that also has a recessed region within the inner surface of hub  295 . When the one-piece needle snaps into place, a noise is emitted such as a clicking noise. This clicking noise indicates to the healthcare worker that the needle is locked in place. The blood flows from the distal portion of one-piece needle  262  and flows toward disk portion  220 . Disk portion  220  prevents the blood from exiting hub  295 . 
     FIG. 16 illustrates a one-piece spiral needle in accordance with one embodiment of the invention. The one-piece needle formed by photolithography comprises a proximal (or head) portion  380  and the distal portion  360 . The distal portion  360  has spirals throughout the length of distal portion  360 . In contrast, a proximal portion typically lacks spirals although it will be appreciated that it may have spirals in an alternate embodiment. It will be also be appreciated that the number of spirals depend upon the requirements of the health care worker. For example, the more spirals used, the more blood volume the needle can accommodate. This provides the healthcare worker with a better opportunity to observe flashback. The spirals that are formed extend toward the center of the one-piece needle. The diameter of the recesses may range from 0.03 to 0.2 inches. 
     In order to form spirals, after one side has completed the photolithographic process, the substrate is flipped and undergoes the process illustrated in FIGS. 1-5. In this manner, a plurality of spirals may be formed. Additionally, the one-piece needle may have a groove portion at the top portion of the one-piece needle. The groove potion is also formed by implementing techniques of the invention. 
     FIG. 17 illustrates the one-piece spiral needle inserted into a catheter and hub. The hub is located at  395 . The diameter of the one-piece spiral needle and hub may range from 0.15 inches to 0.35 inches. The number of spirals that may be used for the lowest to the highest gauge may range from 5 to 15. 
     FIG. 18 illustrates one embodiment of the invention for forming a one-piece needle. The one-piece needle comprises a substantially rectangular portion head (or handle) shaped head  425  and a distal portion  450  of the one-piece needle. At point  434 , portion  440  does communicate with portion  450 . 
     FIG. 19 illustrates the one-piece needle formed from the process illustrated in FIGS. 1-5 locked in place by using a catheter and hub that has a recessed region for receiving portion  440  of the one-piece needle. 
     FIG. 20 illustrates a one-piece needle that comprises a substantially cylindrical or substantially square head at the proximal end formed by segments  580  and  590 . Section  580  may range in length from 0.5 inches to 2.0 inches. The length and diameter of needle portion  560  depends upon the gauge of the needle used as described above. FIG. 21 illustrates the one-piece needle formed in FIGS. 1-5 inserted into a hub and catheter. 
     FIG. 22 illustrates a one-piece needle that comprises a head that has a straight portion  625  and an angled portion  620  that are joined together at disk portion  630 . Needle portion  640  forms the distal portion of the one-piece needle. Straight portion  625  has a length that ranges between 0.5 to 2.0 inches. Angled portion  620  generally has a radius that ranges from approximately 0.4 to 1.0 inches. 
     FIG. 23 illustrates the one-piece needle formed from the process shown in FIGS. 1-5 inserted into a catheter and hub. It will be appreciated that the one-piece needle tip formed from this process is solid. Additionally, the one-piece needle may have a surface groove. The surface groove may have a variety of shapes as illustrated in FIG. 9 to  13 , and  24  to  29 . 
     Given the variety of one-piece needles that may have surface grooves, FIGS. 24 through 29 illustrate a variety of surface grooves in the one-piece needles formed by using techniques described herein. 
     FIG. 24 illustrates a cross-section of a solid tip needle with a surface groove in accordance with an embodiment of the invention. Surface groove  60  is substantially circular in shape and is located in the wall of needle  40  near the outer diameter of needle  40 . The surface groove has a depth that ranges from 0.001 inches to 0.05 inches depending upon the needle gauge. It will be appreciated that surface groove  60  generally extends the length of needle  40  or any portion thereof. 
     In yet another embodiment of the invention, FIG. 25 illustrates a cross-section of a solid tip needle with a substantially rectangular portion shaped surface groove with one side that is open. Surface groove  62  ranges from 0.001 inches to 0.05 inches and the width  63  ranges from 0.001 inches to 0.05 inches both depending upon the needle gauge. Surface groove  60  allows blood to enter at the distal end of surface groove  60 . 
     FIG. 26 illustrates a cross-section of a solid tip needle with a surface groove having a substantially v-shape in accordance with an embodiment of the invention. Each side that makes up the v-shape ranges from 0.001 inches to 0.05 inches depending upon the needle gauge. With this shape of a surface groove, blood flow will have an increased rate of speed at the outer ends of the v-shaped surface groove and a slower rate of movement at the central end of v-shaped surface groove. 
     FIG. 27 illustrates a cross section of a solid tip needle with one surface groove  64  having a substantially half-circle shape in accordance with an embodiment of the invention. The surface groove has the depth approximately in the range of 0.001 inches to 0.05 inches depending upon the needle gauge. Surface groove  64  is formed at the outer surface of needle  40 . Surface groove  64  may extend the length of needle  40  or any portion thereof. Because needle  40  is solid, blood flows around the side of needle  40  into and through surface groove  64 . 
     In yet another embodiment of the invention, FIG. 28 illustrates a plurality of substantially half-circle surface grooves  68  in solid tip needle  40 . The depth of each substantially half circle ranges from 0.001 inches to 0.05 inches depending upon the needle gauge. Blood or other bodily fluids flow through surface groove  68 . 
     FIG. 29 illustrates a plurality of substantially v-shaped surface grooves  66  in accordance with an embodiment of the invention. Each surface groove may extend the entire length of needle  40  or any portion thereof. As noted previously, the flow of blood travels at an increased rate at the outer ends of the v-shape and flows more slowly at the central portion of the v-shape surface groove. Each side of the v-shape surface groove ranges from 0.001 inches to 0.05 inches depending upon the needle gauge. 
     In the preceding detailed description, the invention is described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.
A method and an apparatus is disclosed for forming a one-piece introducer needle having a member portion and a needle portion by introducing a photoresist on a substrate. The temperature of the substrate is increased and then decreased. A photomask is deposited onto a substrate.