How are injection needles made

An Disposable sterile syringe object of the present invention is to provide a needle suitable for hypodermic injection, in which the needle can be inserted basically without forming folds, and injection with this needle only takes up one hand. Although the injection of insulin is described as an example, this needle can be used for all types of subcutaneous injections, for example, injection of growth hormone.US Patent  mentions that an injection part with a total length of 8-12 mm is provided on the needle. Compared with the commonly used 16mm long needle, this length obviously reduces the risk of intramuscular injection. However, for thin men, the total thickness of the epidermis and subcutaneous tissue may even be less than 8mm. Therefore, its intramuscular injection The danger is still unacceptable.It is known from US Patent No. 5 015 235 that the effective length of a needle with a length of 12.5 mm can be changed by installing a sleeve coaxially surrounding the needle with a certain distance from the needle on the needle seat.

The sleeve only leaves a minimum injection length for the needle. Sleeves of different lengths can retain a needle length of 4 or 8mm free to penetrate the skin. The effective length of the needle can only be accurately defined when inserted perpendicular to the skin, and if the needle is inserted at an oblique angle, the effective length of the needle is further reduced in an inaccurately defined manner.A needle with a length between 3mm and 4mm has been imagined, but such a short needle will not penetrate the epidermis, especially when the needle is inserted at an oblique angle.When the needle with the total length of the needle injection part extending from the fixed end of the needle on the needle seat to the skin piercing end of the needle according to the present invention is between 4-6mm, the risk of intramuscular injection and intradermal injection is greatly reduced Sex.

The shortening of the total length of the injection part calculated from the supporting end of the needle on the needle seat to the skin puncture point makes it possible to use needles with thinner needle walls to reduce the risk of breakage. This reduced risk cannot be achieved by using a needle that reduces the effective length through a sleeve that surrounds a part of the needle but does not support the needle.Since it is possible to inject insulin with a needle as thin as  a thin-walled needle with an inner hole larger than 0.133 mm corresponding to the smallest inner hole of the  needle can also be used for injection. If the outer diameter is set to the maximum outer diameter allowed by the needle, then the thin wall allows an inner hole larger than the usual G0 needle.

According to an embodiment of the present invention, the outer diameter of the needle and the diameter of the inner hole of the needle can be consistent with one of the following conditions the outer diameter is less than, and the inner hole diameter is greater than 0.165 mm, or b the outer diameter is less than 0 298mm, and the diameter of the inner hole is greater than 0.133mm.The present invention will be described in more detail below with reference to the accompanying drawings, in which the accompanying drawings schematically show a needle inserted into a skin area with a part of the underlying muscle layer.The needle holder 1 with an injection needle 2 is fixed on a syringe 3. The injection needle 2 is inserted into the subcutaneous tissue layer 5 through a skin layer 4, and the muscle membrane 10 separates the subcutaneous tissue layer 5 from the muscle tissue 6 with blood vessels 11. In the subcutaneous tissue, there is a certain amount of liquid that has been injected but not yet absorbed by the number.