TU Delft researchers design bluetooth that works without continuous power

If it is up to TU Delft researchers Jasper de Winkel and Przemyslaw Pawelczak, the future of the Internet of Things (IoT) will be one without batteries. They have now added energy-efficient two-way communication via intermittently-powered bluetooth to their arsenal – for hassle-free IoT communication, even when the power runs out. They designed FreeBie: which allows bluetooth to continue to work when the power runs out. The GameBoy Forever previously came from the same researchers.

The world is well on its way to a ubiquitous Internet of Things: trillions of devices that take measurements, perform calculations and communicate with each other. “We want these devices not to use batteries, because they are dangerous, bulky and bad for the environment,” says Jasper de Winkel. With intermittent computing, the devices can perform their essential tasks without errors, purely on the basis of – sporadically available (intermittent) – energy that is extracted from the immediate environment. “The things part had already been solved. With intermittently-powered bluetooth, we are now adding the internet part to this.”

From one– to two-way traffic

Previous solutions for battery-less communication only supported one-way traffic, which means gathering enough energy to send data and then ‘hoping that something will pick up the signal’. The TU Delft researchers wanted to exploit the full potential of the bluetooth protocol: “It is one of the most widely used wireless communication protocols worldwide,” says Przemyslaw Pawelczak. “Most importantly, this is a two-way communication protocol, allowing for remote firmware updates and configuration, among other things.”

Energy efficient

Their bluetooth implementation, called FreeBie, is extremely energy efficient. De Winkel: “In a standard implementation, the bluetooth chip is put into sleep mode when the IoT device does not need to communicate for a while. By precisely storing the network status, we can completely switch off the chip, reducing energy consumption by a factor of ten.”

They have achieved this by using commercially available hardware. Pawelczak: “If we were to integrate our solution into a specially designed system-on-a-chip, it would be the most durable, energy-efficient Bluetooth implementation available on the market yet.” Major manufacturers of bluetooth chips have already expressed their interest.


With two sample implementations, the researchers showed that their new architecture enables hitherto unimaginable IoT applications: a battery-less, solar-powered smartwatch that synchronizes time and email notifications with a smartphone; and also wireless firmware updates over bluetooth. “That had never been done under intermittent power.” De Winkel adds: “We hope this also opens the door for other wireless protocols such as intermittently-powered Wi-Fi, 5G, 6G; you name it.”

More information

The hardware and software of the FreeBie system have been made available as open source and the researchers will present their findings on MobiSys 2022 in June.

Freebie’s source code:

Het artikel: Jasper de Winkel, Haozhe Tang, and Przemys?aw Pawe?czak (Delft University of Technology) Intermittently-Powered Bluetooth that Works, in Proceedings ACM MobiSys June 17-July 1 2022, Portland, OR, USA.