Battery-Free IoT Data Collection

Technological advancements in recent years have given us an unprecedented opportunity to monitor everything from agricultural production to the efficiency of our electrical grid and even our own health. Internet of Things (IoT) devices use the latest in sensing and processing technology to collect and report just about any sort of data that we are interested in. These devices are made from very inexpensive and low-cost components, allowing us to spread them around far and wide, giving us insights that were previously unimaginable.

But one big obstacle still standing in the way of larger-scale IoT device deployments is energy consumption. Since these devices are portable and often placed in remote locations, they typically rely on battery power for operation. Cutting-edge sensing and processing technologies have advanced to the point that they sip power very slowly and are well-suited for such applications. But then there is the matter of reporting the data collected, which requires wireless communication in most cases. And traditional communication methods will drain an IoT device’s battery like nothing else.

Researchers at UC San Diego are pioneering a new technology called ZenseTag that uses passive, battery-free hardware to wirelessly transmit sensor data in real-time, which could transform data collection across a number of fields. The team has developed a method to repurpose widely available, inexpensive RFID tags for passive communication. These tags, typically used for inventory tracking, can now report environmental factors like temperature, humidity, and movement without additional power sources or converters.

RFID tags are designed to do nothing more than digitally transmit their identity to a reader, so the team had their work cut out for them in utilizing the tags to transmit sensor measurements. Similar systems have previously been developed, but they relied on novel, purpose-built sensors for operation. For real-world applications, however, using the wide variety of existing, off-the-shelf sensors is a must.

The team's core innovation lies in using the tags to read and transmit conventional sensor measurements without additional electronics, such as analog-to-digital converters. Conventional sensors convert environmental stimuli into digital signals using power-hungry circuitry, but the ZenseTag approach models the electrical changes across terminals that most sensors produce to modulate an RF signal. This allows analog signals from the sensors to be directly transmitted by the RFID tag without any additional conversion hardware.

Because RFID tags require no power source and can be produced cheaply and deployed in large numbers, they open up possibilities for scalable, real-time monitoring. For example, in agriculture, RFID tags could be placed throughout fields to monitor soil moisture at a granular level, allowing for smarter irrigation based on real-time conditions. Similarly, these tags could be embedded in athletic gear, like shoe soles, to track performance metrics such as force during jumping. In settings like parking garages, RFID tags could be installed to monitor occupancy by detecting when a car occupies a space.

This technology could also be important for data-driven AI applications, as it offers a sustainable, low-cost solution to gather extensive data that AI systems can use for analysis and decision-making. By bypassing the need for batteries and power-hungry components, these RFID-based sensors provide a continuous stream of valuable data without the environmental and logistical drawbacks of traditional sensor networks.