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Wireless Technology Choices For Temperature Monitoring Sensors - Part 1

Mar 24, 2014

You don’t need to be a geek or nerd to make the right wireless choice for refrigeration monitors.

As seen in the previous piece in this series titled NYC Hospital Examines WTM (Wireless Temperature Monitoring) Options, there are several factors to consider in understanding which device will work best to help protect the safety and efficacy of temperature sensitive medicines such as vaccines. Among the ones explored were battery or AC power (or both!) and the use of sensor buffer vials.

The heart of WTM sensors is the wireless technology itself. Wireless sensors can be easier to install since they do not need to be connected to the site’s IT network via LAN cables. Those that operate solely on battery powered can be easily placed anywhere, some would claim, although that is not exactly true and comes to the heart of the matter: WTM devices are like Kryptonite confronting lead, they cannot penetrate everything. And those limitations are dictated by the wireless technology embedded in the device. So a look at the offerings and some words about their suitability under various circumstances is called for.

Comparison of range vs. peak data rate for wireless communication technologies used in Wireless Temperature Monitoring (WTM) devices. (Link to Source)

Peak data rate is one of the factors for wireless communications. For WTM devices peak data rate is almost never an issue. Unlike computers, tablets and smartphones that are uploading or downloading megabytes of data very quickly, temperature readings contain very little data (temperature, date, time, device ID, etc.), a few to several bytes for each reading. And because refrigeration monitoring almost never requires continuous monitoring, every second for example, the number of transmissions is small. This is because of two factors. First, WTM devices that report and send alarm or alerting messages if the temperature changes from one second to the next will invariably send out dozens if not hundreds of alerts that are non actionable, a refrigerator door is left open for 30 to 60 seconds for example. Medications in the refrigerator are not at risk when this happens. They are at risk if the temperature rises above the alert level and stays there for several minutes. This is one reason buffer vials are used, to dampen out momentary temperature spikes that are not meaningful.

Medical refrigerator with door open for several seconds or even a minute does not generally put medications at risk. Using a sensor buffer vial can give better insight to temperatures of medications during excursions. (Link to Image Source)

WTM devices are typically set to read and transmit the temperature every few minutes, 2 to 5 minutes for example and in some cases every 10 to 15 minutes. At one site a large medical freezer is monitored every 15 minutes because the staff knows that with the door closed they have up to six hours to recover or move sensitive materials to another unit without exceeding temperature limits. Each hospital will need to experiment with monitoring intervals and temperature limit settings to find the right balance between too much and too little. This generally happens quickly, especially if very tight limits and frequent monitoring is chosen in the start. Getting dozens of notifications when staff is searching for a medication or several door openings occur within a relatively short time will help find the balance to insure medication safety and efficacy.

The next piece in this series will explore the range portion of the graphic.

Temperature@ert’s WiFi, Cellular and ZPoint product offerings linked to the company’s Sensor Cloud platform provides a cost effective solution for organizations of all sizes. The products and services can help bring a laboratory or medical practice into compliance with minimum training or effort. For information about Temperature@lert’s Cellular and Sensor Cloud offerings, visit our website at or call us at +1-866-524-3540.

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Written By:

Dave Ruede, Well-Versed Wordsmith

Dave Ruede, a dyed in the wool Connecticut Yankee, has been involved with high tech companies for the past three decades. His background in chemistry and experience in a multitude of industries such as industrial chemicals and systems, pulp and paper, semiconductor fabrication, data centers, and test and assembly facilities informs his work daily. Well-versed in sales, marketing, management, and business development, Dave brings real world experience to Temperature@lert. When not crafting new Temperature@lert projects, Dave enjoys spending time with his young granddaughter, who keeps him grounded to the simple joys in life. Such joys for this wordsmith include reading prize winning fiction and non-fiction. Although a Connecticut Yankee, living for a decade in coastal California’s not too hot, not too cold climate epitomizes Dave’s favorite temperature, 75°F.

Temperature@lert Dave Ruede

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