Reuse of improperly sterilized steel hypodermic needles is a leading factor in cross infection of diseases between people in specific groups such as patients in developing countries and drug addicts. Disablement after single use is a potential strategy to reduce disease spreading, but disablement of expensive steel needles requires specialized equipment and is a concern in developing countries. Needles made using micromolded polymer are examined in this study as a potential replacement for steel needles. Instead of using specialized tip cutting instruments for steel needles, soft polymer needles can be easily disabled. Material cost and processing temperature of polymer needles are lower than steel. However, further reduction of cost is limited due to the low production rate in conventi...[ Read more ]

Reuse of improperly sterilized steel hypodermic needles is a leading factor in cross infection of diseases between people in specific groups such as patients in developing countries and drug addicts. Disablement after single use is a potential strategy to reduce disease spreading, but disablement of expensive steel needles requires specialized equipment and is a concern in developing countries. Needles made using micromolded polymer are examined in this study as a potential replacement for steel needles. Instead of using specialized tip cutting instruments for steel needles, soft polymer needles can be easily disabled. Material cost and processing temperature of polymer needles are lower than steel. However, further reduction of cost is limited due to the low production rate in conventional micro-molding. In this study, we analyzed the flow behavior of polymer in the micro-molding process using FEM and determined that runner length limits the production throughput. On the basis of the FEM results, we developed a high throughput, hot embossing production method with multi-parallel material delivery. This process allows multiple molding of needles in a single operation. Standard 22 gauge acetal polymer needles were successfully fabricated. Puncture and buckling tests were conducted to examine the mechanical behavior of the polymer needles on silicone rubber. The puncture load ranged between 1 – 1.5N. While this puncture load is higher than that required for commercial steel needles, it is below the critical buckling load of the polymer needles and is within the range of load suited for human administration. We conducted puncture tests using polymer needles and achieved 8mm needle penetration in silicone rubber, which is the working range of hypodermic injections. The successful development of a high throughput fabrication method is demonstrated in this study and polymeric needles are shown to be suitable for use as a potentially low cost replacement for steel needles.