Engineers Achieve 28-Microwatt WiFi Radio, Enabling Batteryless Smart Devices

• The new ultra-low WiFi radio consumes only 28 microwatts to transmit data at 2 megabits per second over a range of 21 meters.
• It could enable batteryless smart devices and completely wireless home setups. 

Despite the continuously growing popularity of Internet of Things (IoT) devices, their utility has been limited by their battery life. A significant fraction of the energy consumption in these devices comes from the WiFi radio, especially when transmitting data at high peak rates.

Existing WiFi radios usually takes hundreds of milliwatts of power to connect IoT devices with WiFi transceivers. This is why devices with inbuilt WiFi require either frequent recharging, external power sources, or large batteries to run.

Now researchers at the University of California San Diego have developed a tiny device that uses about 5,000 times less power than existing WiFi radios to connect IoT devices with standard WiFi networks.

The device consumes only 28 microwatts (µW) to transmit data at 2 megabits per second over a range of 21 meters. It can be integrated with smartphones, small cameras, and sensors. Customers do not have to buy additional equipment, as it can enable direct communication between IoT devices and a nearby WiFi access point.

How Does It Work?

To operate on significantly low power, the WiFi radio transmits data by utilizing a method called backscattering. In physics, backscattering refers to the reflection of waves or signals back to the direction from which they came. It is mostly used in photography, astronomy, and ultrasonography.

Reference: UC San Diego

This newly developed chip captures incoming radio waves (WiFi signals) from a nearby WiFi access point or device (such as a laptop). It then alters the signals, encoding its own data onto them. Finally, the encoded signals are reflected onto a separate WiFi channel to another access point or device.

Extremely-low power WiFi radios integrated into tiny chips. Each chip measures 1.5 square millimeters in area. | Credit: David Baillot | UC San Diego

To build such a low-power WiFi radio technology, the research team developed a component named wake-up receiver. It is responsible for ‘waking up’ the WiFi radio only when IoT devices need to transfer/receive data. The rest of the time, it stays in low power mode, consuming just 3 µW of power.

The research team also showcased an improved version of their technology, which features a custom integrated circuit for backscattering data. This makes the whole system compact and more efficient, allowing the device to operate over larger distances (up to 21 meters).

Read: New Flexible Device Can Transform WiFi Signals Into Electricity

All in all, this the first pragmatic chip that can be deployed in low-power, compact devices. According to the researchers, it can accelerate the development of lower power wearables, batteryless smart devices, and more portable, completely wireless home setups.