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Improve medical sterilization with FRAM RFID

Posted: 26 Jun 2012     Print Version  Bookmark and Share

Keywords:Radio frequency identification  sterilization  FRAM 

During the process of cultivating enzymes, cultures, vaccines and medicines, contamination must be completely avoided. Equipment and devices like couplers, tubing, and containers used in bioprocessing need to be carefully treated and cleansed.

There are different methods of achieving a sterile product or instrument. The most common way to kill microorganisms like bacteria, fungi and viruses is by exposure to heat and pressure in an autoclave. For sterilization during manufacturing a more elaborate method comes into play: irradiation by gamma, e-beam or ethylene oxide (EtO) gas.

Tracking sterilized products
Products that are sterilized using these processes need to be tracked. Typically, some simple form of marking (e.g., a chemical indicator that changes color when it has been used) indicates something has been sterilized. Sometimes the item itself has no marking except an air-tight package (e.g., a plastic bag covering each syringe). It is difficult to prevent re-use of sterilized items with existing marking methods.

Radio frequency identification (RFID) technology has become useful in this process. RFID has a long history of use in logistics processes, which deploy an electronic RFID tag with a unique ID similar to barcode labels. Unlike barcodes, RFID tags can be read via an air interface. This contactless interface does not require the line-of-sight and direct optical contact conventional barcodes need. For example, the anti-collision scheme—a significant feature of RFID technology—enables many RFIDs in close proximity of the RF field to be identified distinctly. So it is possible to track and identify products or objects without opening or unpacking the container(s).

With expanded memory capacity, the electronic RFID labels allow additional data beyond a simple ID code to be stored on the tags. Data can be written during the manufacturing process (e.g., lot number, manufacturing date, expiration date, and product type) and throughout the supply chain process (e.g., factory departure date, date of sterilization and name of logistic partner).

For medical instruments and products in particular, it is imperative the objects be reliably identified and that their treatment and manufacturing history be documented. Monitoring and checking processes can be included in the logistic operation to prevent counterfeiting and help assure product reliability. It is also possible to use RFID to ensure that authorized disposable parts are properly attached to the right equipment to minimize potential risk of misuse. RFID can be attached to the disposable parts, which must be verified by the reader located in the connecting equipment to ensure authorized parts are being used.

RFID has another advantage as well. Without RFID, there is no easy way to track whether a sterilized piece of equipment is being re-used. RFID ensures the tool or equipment has been properly sterilized at a certain date and place, and helps prevent re-use because the data in the RFID cannot be easily changed by the user or other medical personnel.

However, conventional E2PROM-based RFID products face a significant drawback—they cannot withstand the radiation process. After irradiation, memory content is erased or corrupted. So, to take full advantage of RFID features for medical applications, it is necessary to combine the gamma ray irradiation process with RFID technologies that use ferroelectric technology.

Figure: FRAM information – logically 0 or 1 – is contained in the polarization of the ferroelectric material lead zirconate titanate, PZT (Pb (ZrTi)O3).

In contrast to conventional non-volatile memories, Flash and E2PROM, the content of an FRAM cell is not stored in the form of charge carriers in a "floating gate." The information (logically a "0" or "1") is contained in the polarization of the ferroelectric material lead zirconate titanate, PZT (Pb (ZrTi)O3) (figure). This material is placed between two electrodes in the form of a thin film, similar to the structure of a capacitor.

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