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Jeffery Rosino, Jordan Hutchinson, Stephen Grenon; Disabling Single Use Ophthalmic Medical Devices Sterilized with Gamma Radiation. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3698.
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© ARVO (1962-2015); The Authors (2016-present)
Disposable ophthalmic medical devices, at times, need to be disabled to prevent re-use. Using electronic components to disable a medical device can be problematic if gamma radiation sterilization is utilized during the manufacturing process. This report tests the effects of gamma radiation on two methods of disabling a disposable medical device, a simple surface mount fuse and a novel Ferroelectric Random Access Memory (FRAM). The FRAM has the advantage of being able to record treatment data as well as disable the device after use.
Ten circuit boards were built each containing an FM24V10 FRAM by Ramtron. One hundred circuit boards populated with 125mA surface mount fuses and 100 circuit boards populated with 250mA surface mount fuses were also built. The FRAM devices were completely programmed to a preset repeating value. The fuses were measure and shown to be connected and working to specification. Gamma sterilization was performed per ANSI/AAMI/ISO 11137-1:2006 at the 25 kGy level. Following Gamma radiation sterilization the FRAM memory devices content was compared to the pre sterilization state. The FRAM memories were further exercised by reading and writing to all the memory locations to show proper functionality. The fuses were also measured and compared to their pre-radiation state.
The FRAM circuits demonstrated no sign of performance degradation. The content of all one million memory locations remained intact after gamma radiation of 28 kGy and the circuit was able to read and write information to all memory locations. Two of the 100 fuses rated at 125 mA were destroyed as demonstrating by an open circuit, indicating a 2% failure rate. None of the 100 fuses rated at 250mA were destroyed.
The FM24V10 FRAM memory devices can be programmed prior to gamma sterilization with an expectation that the data will not be corrupted by the gamma radiation sterilization process. Furthermore, the FRAM memory device will continue to function normally. However, if a fuse is used to disable the medical device, care should be taken to size the fuse large enough so that eddy currents induced during gamma radiation sterilization do no destroy the fuse.
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