[From June Issue 2014]

Injectors are medical devices that come into contact with our skin. The majority of injectors consist of a syringe filled with medicine and a needle. Many people hate injections due to the moment of pain experienced when the needle penetrates the skin.
A routine blood test or flu shot may be just about the only time healthy people require an injection. Children with type one diabetes, however, need to inject themselves with insulin several times a day. With this problem in mind, MATSUNO Takao, formerly the person in charge of research and development for Terumo Corporation, wondered whether they could develop a needle that would make injections as painless as possible.
Matsuno and his fellow engineers understood that “in order to reduce the pain, it would be necessary to make the needle thinner.” The thinner they make the needle, however, the harder it became to get the medicine to flow through it. In order to minimize pain and maximize the flow of medicine, they came to the conclusion that it was necessary to design a needle with a narrow tip and a wide shaft. But they had a hard time finding a company that would collaborate with them on this project.
In order to find a company that could manufacture a tapered needle, Terumo Corporation’s engineers contacted and visited about a hundred companies. Finally, a small factory, Okano Manufacturing Corporation in Sumida Ward, Tokyo, agreed to take on the project. Normally, injection needles are made from a long pipe cut into a certain length. At Okano Manufacturing, however, they came up with a method of rolling individual sheets of stainless steel one at a time into a tube. So that liquids can flow through unimpeded, the inside of the needle is carefully polished. This production method can only be carried out by Okano Manufacturing.
In 2005, by developing the world’s thinnest needle, “Nanopass” – which has a 33-gauge (0.2 millimeter) tip –they achieved what no other company had managed to before. In 2012, they broke their own record for thinnest needle by constructing an even thinner one with a 34-gauge (0.18-millimeter) tip. This was made possible by Okano Manufacturing’s press-working expertise and Terumo’s needle manufacturing technology.
To reduce the pain of injections even further, they not only made the tip of the needle thinner, but also gave considerable thought to its design. In order to avoid that sharp twinge of pain felt the moment the needle punctures the skin, rather than simply making the tip sharper, they made it asymmetrical, so that the edge of the blade would slice into the skin.
Those with diabetes have to have injections several times a day and this adds up to over a 1,000 injections in a year. Nanopass has been widely used to moderate the physical and emotional pain these patients go through every day. “I am glad to contribute to their medical treatment by alleviating just a little of their pain,” says Matsuno.
Terumo Corporation
Text: ITO Koichi[2014年6月号掲載記事]


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