Robert Brown, marketing executive at medical battery manufacturer Ultralife Corporation, explores how radio frequency identification (RFID) tagging can be used to locate assets that healthcare workers need to do their jobs more effectively.
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RFID
Forty hours is a lot of time — for most of us, it’s a full working week. Nurses in healthcare settings, however, spend this amount of time searching for medical equipment per month (according to a NursingTimes survey). What’s more, in 16% of cases respondents said that they had given up the search after failing to find a piece of equipment.
The underutilisation and loss of medical assets costs the healthcare sector millions of pounds each year. Hospitals that are particularly susceptible are those with multiple buildings and floors, or that have thousands of assets. Getting real-time or last-known location information for these often-critical assets can considerably improve operational performance. Used at numerous NHS trusts and private organisations across the UK, RFID technology enables workers to assign each asset with unique tracking information, which is stored in a tag attached to the asset and located using an RFID receiver.
However, there are several different types of RFID tags and receivers, so which are the most qualified for the job?
Passive RFID tags are the cheapest solution, so are often used to track lower value assets or discardable ones, such as blood vials or test tubes. These tags have no internal power source, so are entirely reliant on energy transmitted from an RFID receiver. Consisting of an integrated circuit and an internal antenna, passive tags are often embedded into adhesive labels that are quick and easy to attach, or sometimes into the device itself.
Alternatively, active RFID tags utilise a battery and use this to transmit a unique ID and location information every time they pass an RFID receiver or at pre-set intervals. To transmit information, active RFID tags contain a beacon or transponder, which is powered by batteries. Active RFID tags are more expensive than passive RFID ones, but it can be worth the cost to ensure more accurate tracking of higher value items such as medical devices (e.g., feeding devices and infusion pumps) or other property (e.g., wheelchairs and beds).
With regards to the battery, size can be a key consideration because a compact battery can help to reduce the size of the tag and, therefore, make it less detectable and harder to remove from the device. Ultralife’s Thin Cells are a perfect example of a discrete battery, measuring as thin as 1.1mm. Thin Cells also retain over 98% of their capacity after one year of storage at room temperature, meaning they are always ready to use regardless as to how devices are stored. This can prove useful in hospitals where equipment could be abandoned anywhere after use.
Finally, there is a type of tag that sits between active and passive, known as semi-passive RFID, which reflects a small fraction of the power emitted by an RFID receiver. As it does not have an onboard transmitter, the read range of a semi-passive tag can be limited. Therefore, semi-passive RFID is best suited for applications where tagged items stay within close range of an RFID receiver or can be scanned regularly, which may be achievable in a smaller hospital but could prove challenging in a larger one.
Active RFID tags, however, contain a beacon/transponder that can transmit signals to a receiver over 20 metres away (sometimes up to 150 metres), depending on frequency levels and other factors. To further expand this distance, in larger hospitals or those with several buildings, instead of buying multiple receivers the hospital can utilise its existing Wi-Fi nodes, which may already cover most of the hospital grounds and are likely to be networked together to share data. However, there may be some areas of the hospital that the Wi-Fi network does not reach or the existing nodes may not be compatible with RFID. In these instances, handheld RFID readers can be a useful option.
As handheld RFID readers may not be in continuous use, they are often powered by rechargeable batteries that are charged between use. Ultralife offers a range of pre-engineered, rechargeable Lithium-ion Soft Packs, in voltages ranging from 3.6V to 14.8V, which have a long cycle life. For original equipment manufacturers (OEMs) who require different voltages or who have bespoke requirements (size, performance etc.), Ultralife also offers a custom battery pack design and manufacturing service.
When it comes to tracking a hospital’s assets and devices, engineers have seemingly been working overtime to devise a wealth of options; with battery-powered active RFID an excellent choice for real-time or last-known location tracking. However, selecting the optimum non-rechargeable battery to power the tags and rechargeable battery to power a handheld reader (if required) can make all the difference to the results.
