Who Needs Batteries? Self-Powered Sensors Can Simplify and Enhance Systems

The growing energy demand and how to meet it is one of the most pressing concerns the world faces. Not only is the volume of production a challenge that requires addressing, but the nature of the production has to be sustainable and free from carbon emissions. 

Scientists, researchers, technologists, institutions, and government organizations globally are trying their best to devise efficient solutions to this energy challenge. Many successful attempts have been helping to improve the scenario as well. 

Amidst all these, a group of MIT researchers has come up with a battery-free, self-powered sensor capable of harvesting energy from the environment. Let’s start by delving deeper and understanding what this technology means and why it is a significant innovation. 

Battery-Free, Self-Powered Sensors from MIT Researchers

These sensors are free from the requirement of rechargeable or replaceable batteries. They also do not require wiring, making them easier for placement in places that are difficult to reach and access. Essentially, these sensors are temperature-sensitive devices that can thrive on energy drawn from the adjacent magnetic field around a wire in the open air. 

Deploying these sensors is as simple as clipping them around a wire carrying electricity, such as those powering a motor. Once clipped, the deployment is sufficient for the sensing device to both harvest and store energy. Additionally, the device is capable of monitoring the motor’s temperature, as well as gathering data on the machine’s power consumption and operations over an extended period.

According to Daniele Monagle, the lead author of the study that highlights this innovation as a paper published in the IEEE Xplore:

“We have provided an example of a battery-less sensor that does something useful and shown that it is a practically realizable solution. Now, others will hopefully use our framework to get the ball rolling to design their sensors.”

While speaking of the innovation and its utility value, John Donnal, an associate professor of weapons and controls engineering at the United States Naval Academy, said: 

“Energy-harvesting systems like this could make it possible to retrofit a wide variety of diagnostic sensors on ships and significantly reduce the overall cost of maintenance.”

The researchers believe that this innovation is a valuable add-on to the world of energy harvesting because it works as an efficient electronic energy management interface between the harvester source and the sensor load. 

The system, during developmental testing, exhibited successful cold-start capabilities that use discrete logic, with average power harvest enhancements reaching close to 400% under certain harvester voltage load conditions. It worked under a hysteretic control method that could service a sensor load as high as 50 megawatts. 

The work was partly supported by the Office of Naval Research and The Grainger Foundation. Fundamentally, the monitoring and sensing capabilities of these devices may have many applications in the world of shipping. 

For instance, accessing and monitoring power on a ship is difficult to carry out as there are a limited number of outlets and strict restrictions relating to the type of equipment that could be plugged in. 

While the ship could significantly benefit from measuring the vibration of a pump, and it could have real-time information on the health of the bearings and mounts, powering retrofit sensors is about building investment-heavy infrastructure. These self-powered sensor systems make it possible to retrofit a range of diagnostic sensors on ships, bringing down the maintenance cost significantly. 

Moreover, the energy harvesting that these sensors do is not only dependent on magnetic fields. They can harvest energy from vibrations or sunlight and could offer capabilities to build wholesome sensor networks for factories, warehouses, and commercial spaces at a very moderate installation and maintenance cost. 

All these discussions around energy harvesting and drawing the required energy from surrounding magnetic fields, sound vibrations, or sunlight may ring a bell to those who are aware of piezoelectric materials. But there are differences. 

Click here to learn about sustainable energy sources and their adoption rates.

The Self-Powered Sensors are Different From Piezoelectric Materials

The piezoelectric materials can produce an electric voltage when placed under stress. The driving factors behind power generation could be bending, stretching, or vibrations. It is possible to leverage these ways of generating electricity through a wave energy device. 

Piezoelectricity has also been put to use as a marine power generation technology. However, it is different from the self-powered sensor systems we discuss here because they only form a part of the system. 

The scientific paper that details the energy management design for self-powered sensors shows that there are three broad components to it. There is the harvester source, core energy management module, and sensor node. 

Piezoelectricity is one of the harvester sources. There could be more such harvester sources, including solar cells, CT MEH sources, and thermoelectric or triboelectric sources. 

Summarily, a self-powered sensor is more than a piezoelectric material or the phenomenon of piezoelectricity per se. And therefore, self-powered sensors find a range of applications. 

In the coming segments, we will look into companies that manufacture such sensors or use them. 

#1. EnOcean: Self-Powered Sensors for Safe Buildings

The wireless self-powered sensors of EnOcean draw energy from ambient light, leveraging solar cells. Not only this, but these sensors are also capable of extracting energy from the smallest temperature differences. In addition to energy harvesting, they can also collect raw data, aiding in the analysis and visualization of the energy dynamics of a smart building. Moreover, apart from temperature, these sensors efficiently gain information about humidity, light, and how space and certain rooms of a building are being used.

EnOcean has a variety of products in its self-powered sensors portfolio, including energy-harvesting wireless sensor modules, ultra-low power DC/DC converters for thermal energy harvesters, energy harvesting magnetic contact transmitter modules and wireless temperature sensor modules, humidity sensor modules, and more. 

EnOcean positions STM 550 as the flagship product in its family of self-powered sensors. It is an energy-harvesting wireless sensor that has many applications in digitized buildings. It is a multisensor product that combines five different sensors working on magnet contact, acceleration, humidity, illumination, and temperature. 

The sensor comes with a solar cell integrated into it, which can fulfill all the operational energy requirements. Even when there is no solar light available, the internally stored harvested energy ensures that the system remains functional. Finally, the NFC interface ensures easy configurability and access through an NFC reader, smartphone, or tablet. 

According to an internal document published by EnOcean, the company recorded a revenue of US$21 million and US$23.2 million in FY 21 and FY 22, respectively, without including any revenue from the acquired assets. For FY 23, the company projected a revenue of US$35 million. 

The company also showcased a strong pipeline of strategic and financial investors, including Eltako Electronics, Wellington Partners, SET Ventures, Siemens, and Emerald Technology Ventures. 

#2. ONiO: Working Towards a Batteryless Future

Another company that has been working rigorously towards fulfilling the demands of a self-powered future is ONiO. 

Its flagship product, ONiO.zero, is a small wireless microcontroller capable of replacing batteries. It is grafted on a tiny piece of silicon that has the required electrical circuitry to accumulate the smallest amounts of energy. 

This nano-sized system can execute programs, connect to external sensors, and communicate wirelessly. It utilizes ambient renewable energy to power microelectronics to achieve a set-up where users can fully leverage RF, solar, and thermoelectric energy to their benefit. 

ONiO.Zero powers many microcontroller devices, including a batteryless remote control. In operating the remote control, ONiO.zero implements a low-power PDM interface for connecting low-power microphones. This interface supports sampling speeds from 300 KHz to 12 MHz, with additional support for fractional bitrate. Furthermore, the integration of a capacitive touch engine means that the remote requires no internal oscillator for operation and is entirely self-clocked. This design allows it to run on extremely low power and to asynchronously wake up the rest of the system. Moreover, the ultra-low-power oscillator is designed so that any keypress, from a total of 64 buttons, is capable of waking up the CPU. 

In July 2023, ONiO unveiled its batteryless electronic shelf labels. These are 100% self-powered and require no batteries at all. Traditional shelf labels use two coin shells each, and an average convenience store uses close to 6,000 of these shelf labels, resulting in frequent disposal of nearly 12,000 coin cells into oceans and landfills from a single convenience store. 

ONiO’s self-powered batteryless electronic shelf labels can save our planet from toxic waste generated from such millions of batteries. 

The company completed its pre-seed, seed, and bridge round of funding in 2017, 2018, and 2021, respectively and is expected to complete Series A by 2024. The latest available funding data suggests that the company raised close to 2.5 million Euros as a grant from the European Innovation Council in May 2020. 

#3. Clarity Movement Co.: Leveraging Air Sensing Technology to Lead the Clean Air Movement

Based out of Berkeley, California, United States, Clarity Movement Co. offers its flagship particulate matter and nitrogen dioxide monitor by the name of Clarity Node-S. It is a self-powered solution that has earned FCC/CE certification. At its core, it is an IoT air quality monitoring system that works on the principles of solar energy harvesting. 

It also has cutting-edge data management capabilities that can be modulated to any project scale. Apart from serving as an air quality monitoring hardware that measures PM2.5 and nitrogen-di-oxide, Clarity Node-S also serves as a platform that can measure Wind, Black Carbon, and Ozone. Its user-friendly dashboard offers air quality measurements and air network status data in the most accessible way possible. 

Clarity Movement has had a total of five funding rounds so far, with the latest series A, on July 24th, 2022. Reportedly, the round was closed for US$9.6 million in raised funds. 

Apart from the companies that are manufacturing batteryless, self-powered sensor solutions, there are application areas that are studying its feasibility and making developments accordingly. 

From Healthcare to Building Intelligent Systems: The Use of Self-Powered Sensors

Sensors have found use in healthcare, the wearable industry, the field of personal electronics, automobiles, buildings, food monitoring, robotics, environmental monitoring, and more. The benefits of sensors have been accentuated further by self-powered sensors. 

Now, there is development happening around integrating machine learning techniques into self-powered sensing systems. Experts believe that augmenting self-powered sensors with ML capabilities will open up avenues for a large-scale deployment of the Internet of Things. 

Successful research has been conducted around self-powered wireless optical transmission for wireless pressure detection. The scientific world has also witnessed the development of 3D-printed elastomeric metal-core triboelectric wristbands, tremor sensors for Parkinson’s, smart socks, and intelligent driver assistance systems – all of which work towards leveraging self-powered sensors. 

In the field of healthcare and biomedical applications, hybrid sensors with ML techniques that can detect biomechanical energy emitted by human motions have come. These sensors power leg-rehabilitation devices and help with on-skin-triggered biomechanical motion and multifunctional pressure sensing and human gesture identification solutions. 

The Road Ahead For a Battery-Free, Self-Powered Future

One of the areas where self-powered, batteryless sensors will help immensely is the deployment of IoT at a global scale. Estimates suggest that potential large-scale IoT deployment requires replacing one billion batteries each day. Energy harvesting techniques will definitely help. 

However, the future of self-powered sensors can only achieve its true potential if it manages to solve a few bottlenecks. The realm of electronics has to become ready to efficiently accept and leverage small power generation modalities that energy harvesting techniques give birth to. 

The world needs to see more progress in developing electronic devices that can run efficiently on low active processing power. The surface charge that contact electrification generates has to increase to harvest adequate energy that can power our everyday-life electronic gadgets. For successful application in human motion detection activities, effective management of the available data will also play a crucial role. 

With these challenges adequately addressed, self-powered sensors can go a great length in simplifying and enhancing systems that we use on an everyday basis. It will pave the way for energy that has the least carbon footprint and is sustainable at its core.