The recent pandemic caused by the Covid19 virus and the subsequent race against time to develop vaccines has brought to the fore the importance and issues related to the cold chain. Some of these vaccines are very sensitive to temperature variations and require storage at very low temperatures, even below -70°C. These temperature levels must also be strictly maintained, with very low tolerances, from the point of production to the facility where it will be administered to the patient.
The term “cold chain” refers to the supply chain for materials that could be compromised or irreparably damaged if the temperature at which they are stored is not kept within very narrow limits. Many pharmaceutical, chemical and food products fall into this category. To ensure that the cold chain is maintained without ever being interrupted, it is necessary to develop a tracking system that is as comprehensive, automated, and error-free as possible.
Asset tracking has the task of tracing products or materials along each stage of the path that divides them from the place of production to the end-user so that, at any time, it is possible to determine the place where the asset is located. The simplest way for tracking is to apply a barcode with a unique identifier to each asset. The code can then be scanned with a barcode reader or be recorded each time it is moved from one point to another along the chain.
Today, all of these steps and movements can be recorded in a centralized tracking database for further analysis and query.
The evolution of electronic technology has led to the introduction of innovative low-power electronic devices for tracking assets, such as temperature, humidity, shock/vibration, and contaminants sensors, plus GPS locators.
Very important in this area are also the data loggers, devices capable of recording and keeping stored the information coming from the sensors relating to the tracking process. Most data loggers used in asset tracking applications have low power consumption and can therefore be battery-powered. The diagram on the left shows some classic asset tracking applications that use data loggers. These devices include a sensor to acquire the data to be logged, a processor, non-volatile memory for data storage, and a real-time clock (RTC).
Data loggers are common in cold chain tracking systems, as they avoid having to resort to frequent connections (typically via internet or mobile network) with the centralized system.
Cold chain asset tracking application
Temperature monitoring and recording are not only essential to ensure the integrity of the product, but also represent a requirement imposed by the Federal Drug Administration (FDA) for monitoring the quality of food, drugs, and cosmetics.
It is, therefore, necessary to use a low-power, battery-powered device capable of acquiring and storing the temperature at regular time intervals. In addition to the data logger, we will also need a low-power microcontroller, the real brain of the tracking system, capable of executing software control algorithms and interfacing with sensors, displays and serial or USB communication channels.
One example of a microcontroller capable of meeting these requirements is the ML630Q466/Q464 from Lapis Technology (belonging to the Rohm group), a 32-bit low power microcontroller based on an Arm Cortex-M0+ core with two different flash ROM sizes (128 KB / 64 KB) and able to support USB interface. These microcontrollers feature different serial ports for connecting multiple sensors and logging their output. They have built-in LCD drivers, RC-ADC for an accurate temperature measurement, USB 2.0 full speed controller and support multiple clock modes. This level of integration eliminates the need for many external components, allowing a more compact design. As shown in the diagram below, the MCU can be battery powered by virtue of its low power consumption, it can manage a multitude of external sensors, a display, a USB communication channel, and a module for wireless connectivity (optional).
There are a wide selection of sensors capable of covering the requirements of a cold chain tracking application. These sensors include accelerometers, optical sensors (ambient light, RGB), MEMS-based pressure sensors, and magnetic sensors (Hall ICs and magnetometers). Accelerometers such as KXTJ3-1057 can be used to detectmotion wake-up, angle detection, impact/free fall detection, activity, tap sensing, motor health and machine health.
For optical sensors, ambient light sensors are great for monitoring light intensity in an environment or for backlight control of the data logger. The RGB color sensors 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, hall ICs are ideal 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.
In addition to USB connectivity, the addition of a module capable of supporting wireless communication represents a fascinating opportunity, paving the way for a possible integration of the tracking system with the Internet of things (IoT) framework.
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 include standard protocols such as Bluetooth (especially low power), WiFi, and other more specialized IoT protocols.