The term “cold chain” refers to the supply chain that delivers products or materials that will be spoiled or destroyed if temperature varies beyond a prescribed range. Many food items, chemicals, and pharmaceuticals require tightly controlled “cold chain” logistics. Monitoring these “assets” through the entire cold chain, and being able to guarantee the temperatures seen by them at all times, can provide an assurance of quality. 

These logistics can be handled by sensors, microcontrollers, and even IoT capabilities to ensure safe handling of cold assets across the supply chain.

Some vaccines, like Pfizer’s COVID-19 vaccine, are highly sensitive to temperature variations. In fact, Pfizer’s vaccine requires super-cold storage, with temperature maintained at -70°C or below. This temperature needs to be maintained from the point of manufacture all the way through the delivery supply chain until the vaccine can be administered to the patient.

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Application: Cold Chain Asset Tracking Data Logger

Let’s consider a specific application: a cold chain asset tracker with data logging.

The FDA requires the monitoring of the quality of food, drugs, and cosmetics by measuring the asset temperature and storing logs of the historical temperature data over time. To do this, the first requirement is a very low power device—so low that it can be battery powered for weeks, months, or even longer. This device needs to, at a minimum, measure temperature periodically and record it in a data log. 

The US government actually requires these electronically stored data logs, per a US cold chain standard that was established in the 1990s, and has gone on to become the global standard. This standard requires the data log to be represented as a PDF for immediate human readability via USB.

But beyond the bare minimum requirements, these devices are capable of much more. Additional sensors, computing/memory, or communication functions offer many new opportunities.

Microcontrollers as the “Brains”

A cold chain asset tracker like what is described above first needs a microcontroller to act as the “brain” of the device. This microcontroller needs to be very low power, have multiple serial ports to connect to sensors, enough memory to run the necessary programs and algorithms, and have the proper communication interfaces for USB, displays, etc. 

On top of all of that, the microcontroller needs to be physically small to enable a compact design.

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The Lapis Technology (part of the ROHM Group) ML630Q466/Q464 are ARM Cortex-M0+ -based 32-bit low power microcontrollers with two different Flash ROM sizes (128 KB/64 KB) and are suited for situations where a USB interface is required for communication. Depending on algorithms running on the data logger, customers can choose the correct memory size for their application.

These micros have multiple serial ports for connecting multiple sensors and logging the output of these sensors. They have built-in LCD drivers, RC-ADC for measuring temperature precisely, USB 2.0 full speed controller and multiple clock modes. 

This high level of integration eliminates many external components for a more compact design. The internal power saving mode contributes to long battery life for battery-operated applications.

Sensors Filling in the Picture

A wide array of sensor nodes offer the capabilities needed for asset tracking data loggers. ROHM’s sensors for these applications include accelerometers, optical sensors (ambient light, RGB), MEMS-based pressure sensors, and magnetic sensors (Hall ICs, magnetometers).

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The table here summarizes the various sensors’ features and their target uses for tracking. 

Accelerometers can be used to detect motion wake-up, angle detection, impact/free-fall detection, activity, tap sensing, motor health, and machine health. 

For optical sensors, ambient light sensors can monitor light intensity in an environment or for backlight control of the data logger. 

High-accuracy RGB color sensors can detect color changes of an object, sorting products, and matching products of a given color. 

In addition, barometric pressure sensors can help detect changes in altitude, indoor navigation, weather stations, and pressure changes. 

Lastly, magnetic sensor offerings complete the list with Hall ICs and magnetometers. Hall ICs are great for door detection, wake-on detection, contactless switches, and front/back position, while magnetometers are great for location/position detection and used as eCompass for trackers.

The IoT in the Chain

Beyond the basic and required USB connectivity, the addition of a wireless communication module creates a pretty fascinating possibility, making the asset tracker part of the Internet of Things (IoT). 

In the connected IoT space, sensor nodes offer the capabilities needed for asset tracking data loggers. Sharing data with other nearby assets and other parts of the surroundings allows the asset tracker to have the most comprehensive picture possible of the environments experienced by the asset. 

Wireless communication modules could be Bluetooth, Wi-Fi, or other more specialized IoT protocols. The ROHM Group offers a number of wireless solutions including Sigfox, Wi-SUN, and Bluetooth Low Energy through the LAPIS side of their business.

Conclusion

ROHM offers an industry-leading complete solution for a cold chain asset tracker with data logging. Utilizing a Lapis Technology brand microcontroller, Lapis Sigfox, Wi-SUN, and Bluetooth

Cold chain asset trackers with data logging require a microcontroller, wireless connectivity, and sensors for close monitoring and tight control or cold chain logistics. ROHM offers all of these solutions utilizing Lapis Technology and Kionix sensors.

For more information, please visit ROHM.com, Lapis-Tech.com, and Kionix.com.

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