Battery-free smart devices to harvest ambient energy for IoT

The Internet of Things allows our smart home gadgets and wearable technologies like our smartwatches to communicate and work together. Image Credit: Ponchai nakumpa via Pixabay

Tiny Internet-connected electronic devices are becoming ubiquitous. The so-called Internet of Things (IoT) allows our smart home gadgets and wearable technologies like our smartwatches to communicate and work together. IoT devices are increasingly being used in all kinds of industries to drive interconnectivity and intelligent automation as part of the “fourth industrial revolution”.

The Fourth Industrial Revolution builds on already widespread digital technologies such as connected devices, artificial intelligence, robotics and 3D printing. It is expected to be an important factor in the revolution of society, economy and culture.

These small, self-contained, interconnected and often wireless devices already play a key role in our daily lives by helping to make us more resource and energy efficient, organized, safe, secure and healthy.

There is, however, a major challenge: how to power these tiny devices. The obvious answer is “batteries”. But it is not that simple.

Small appliances

Many of these devices are too small to use a long battery life, and they are located in remote or hard-to-reach places – for example in the middle of the ocean to track a shipping container or on top of a silo to grain, to monitor grain rate. These types of locations make servicing certain IoT devices extremely difficult and commercially and logistically impractical.

Mike Hayes, Head of ICT for Energy Efficiency at the Tyndall National Institute in Ireland, summarizes the market. “We are projected to have a trillion sensors in the world by 2025,” he said, “that is, a trillion sensors.”

That number isn’t as crazy as it first appears, according to Hayes, who is the coordinator of the Horizon-funded EnABLES (European Infrastructure Powering the Internet of Things) project.

If you think of the sensors in technology that someone might be wearing or having in their car, home, office, and the sensors embedded in the infrastructure around them, like roads and railroads, you can see where that number is coming from, he explained. .

“In the world of billions of IoT sensors predicted for 2025, we will be throwing over 100 million batteries into landfills every day unless we significantly extend battery life.”

– Mike Hayes, EnABLES

Battery life

Landfill is not the only environmental concern. We also need to determine where all the materials needed to manufacture the batteries will come from. The EnABLES project calls on EU and industry leaders to think about battery life from the start when designing IoT devices to ensure that batteries do not limit lifespan machines.

“We don’t need the device to last forever,” Hayes said. “The trick is that you have to survive the application you’re serving. For example, if you want to monitor industrial equipment, you probably want it to last five to ten years. And in some cases, if you’re doing anyway regular maintenance every three years, once the battery lasts more than three or four years is probably sufficient.

Although many devices have an operational life of more than 10 years, the battery life of wireless sensors is typically only one to two years.

The first step in extending battery life is to increase the energy supplied by the batteries. In addition, reducing the power consumption of devices will extend battery life. But EnABLES goes even further.

The project brings together 11 leading European research institutes. Along with other stakeholders, EnABLES is working to develop innovative ways to harvest tiny ambient energies such as light, heat and vibration.

Harvesting these energies will further extend battery life. The goal is to create self-rechargeable batteries that last longer or ultimately work on their own.

Energy harvesters

According to Hayes, ambient energy harvesters, such as a small vibration harvester or an indoor solar panel, that produce low amounts of power (in the milliwatt range) could significantly extend battery life. many devices. These include everyday items like watches, radio frequency identification (RFID) tags, hearing aids, carbon dioxide detectors, and temperature, light, and humidity sensors.

EnABLES also designs the other key technologies needed for small IoT devices. Not content with improving energy efficiency, the project is also attempting to develop a standardized and interoperable framework and technologies for these devices.

One of the main challenges of self-powered IoT tools is power management. The power source can be intermittent and at very low levels (microwatts), and different harvesting methods provide different forms of energy that require different techniques to convert to electricity.

Regular net

Huw Davies, is managing director of Trameto, a company that develops power management for piezoelectric applications. He points out that energy from photovoltaic devices tends to come in a steady trickle, while that from piezoelectric devices, which convert ambient energy from motion (vibration) into electrical energy, typically comes in bursts.

“You need a way to store that energy locally in a store before it comes into a load, so you need to have ways to manage that,” Davies said.

He is the coordinator of the Horizon-funded HarvestAll project, which has developed an energy management system for ambient energy called OptiJoule.

OptiJoule works with piezoelectric materials, photovoltaics and thermal electric generators. It can work with any of these sources alone or with several energy harvesting sources at the same time.

The goal is to allow autonomous sensors to be autonomous. In principle, it is quite simple. “What we’re talking about are ultra-low-power sensors taking digital measurements,” Davies said. “Temperature, humidity, pressure, whatever, with the data provided on the Internet.”

Integrated circuits

The HarvestAll energy management integrated circuit device adapts to different energy harvesters. It takes the different and intermittent energy created by these recuperators and stores it, for example in a battery or a capacitor, and then manages the supply of a constant energy output to the sensor.

As with the EnABLES project, the idea is to create a standardized technology that will enable the rapid development of long-lived/autonomous IoT devices in Europe and globally.

Davies said the power management circuit operates completely autonomously and automatically. It is designed so that it can simply be plugged into an energy harvester, or a combination of harvesters and a sensor. As a battery replacement, it has a significant advantage, according to Davies, because “it’ll just work.”

The research in this article was funded by the EU.

This article originally appeared in Horizon, the European research and innovation magazine.

Horizon Magazine brings you the latest news and features on challenging science and innovative EU-funded research projects.

Horizon Magazine brings you the latest news and features on challenging science and innovative EU-funded research projects.

About Anne Wurtsbach

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