Imagine that when you open your fridge, an app on your phone immediately lets you know which items will expire within a few days. This is one of the valuable applications of a new technology developed by engineers at the University of California San Diego.

This technology presented at the 2023 IEEE International Solid-State Circuits Conference combines a chip integrated into product packaging and a software update on your phone. The phone becomes capable of identifying objects based on signals the chip emits at Bluetooth or Wi-Fi frequencies. In an industrial setting, this means that a smartphone equipped with the software update could be used as an RFID reader.

The work harnesses breakthroughs in backscatter communication. It uses signals already generated by a smartphone and re-directs them back in a format your phone can understand. Effectively, this technique uses 1000-times less power than state-of-the-art techniques to generate Wi-Fi signals. Already, these advances have enabled applications such as on-body sensors or asset trackers.

The custom chip, which is roughly the size of a grain of sand and costs only a few pennies to manufacture, needs so little power that it can be entirely powered by LTE signals, a technique called RF energy harvesting. The chip turns Bluetooth transmissions into Wi-Fi signals, which can in turn be detected by a smartphone with that specific software up-date.

This breakthrough represents the first backscatter integrated circuit that can enable wireless communication and battery-free operation coming from a single mobile device.

This approach enables a robust, low-cost and scalable way to provide power and enable communications in an RFID-like manner, while using smartphones as the devices that both read and power the signals.

The technology’s broader promise is the development of devices that do not need batteries because they can harvest power from LTE signals instead. This in turn would lead to devices that are significantly less expensive and last up to several decades.

The researchers achieved this breakthrough by harvesting power from LTE smartphone signals and buffering this power onto an energy storage capacitor. This in turn activates a receiver that detects Bluetooth signals, which are then modified into reflected Wi-Fi signals.

The software update is simply a bit sequence that turns the Bluetooth signal into something that can be more easily turned into a Wi-Fi signal.

In addition, most lower power wireless communications require custom protocols, but the device the researchers developed relies on common communication protocols: Bluetooth, Wi-Fi and LTE. That’s because smartphones are equipped with both a Bluetooth transmitter and a Wi-Fi receiver.

The device currently has a range of one meter, is half a square inch in size, and costs just a few cents to manufacture.

The team hopes to commercialize the device, through a startup or an industry partner.