One of the interests at this year’s annual Consumer Electronics Show (CES) is to not only go wireless but batteryless, too. One proposed solution comes from two companies, e-peas and Sequans Communications, which announced a collaborative project to create a continuous battery-less IoT solution—without any maintenance.
Challenges of Battery-Less Designs
Because it would be exhaustive to replace the millions of batteries of IoT devices in smart cities, engineers have turned to various energy-harvesting methods in their designs.
For instance, solar photovoltaic (PV) cells would, in theory, be able to harvest energy from the sun for continuous power. The downside to this form of energy storage and supply is that harvesting is unpredictable.
Example of a wireless sensor network node powered by solar energy harvesting. Image used courtesy of the Journal of Sensor and Actuator Networks (PDF)
Handheld devices may have limited exposure to sunlight, so some devices are built to absorb sufficient energy from indoor illuminance (lux) levels. However, these devices are prone to turn on and off at random time intervals due to power failures.
Finally, some designs rely on radio frequency to DC power converters to remain battery-less. For instance, Wiliot, an Israelian fabless semiconductor company, harvests radio waves from a device smaller than a standard postage stamp. The issue that arises with these systems is that they must remain in close proximity to function properly, limiting design flexibility.
e-peas’ “Ambient Energy Manager”
e-peas focuses on delivering energy-harvested solutions to move away from batteries and external power supplies. From thermal energy solutions to vibration and photovoltaic cells, e-peas explores many hardware solutions to achieve this battery-less future.
The recently-launched AEM10941 is an IC with an energy source based on photovoltaic cells with a dual-cell supercapacitor as storage management. The AEM IC delivers autonomous abilities for switching between primary and secondary battery options.
The block diagram of the AEM10941 shows a self-reliant system that can recharge, store, and deliver power continuously. Image used courtesy of e-peas
The IC is designed to deliver power to any sensor wirelessly. System redundancy is achieved when the storage element is depleted. Then, an optional primary battery source is used to recharge before switching back.
At the center of this component is two regulated switching converters that provide high power conversion. A unique feature is AEM’s ability to “cold start,” which is when the device is able to start from a power-off position, requiring an input of 300 mV, which can be achieved by adding a few resistors. In addition to overcharge protection, each pin receives a warning to the load when battery levels are low.
Sequans’ Monarch LTE-M/NB
After three years of R&D, Sequans claims to have developed a platform for narrowband IoT applications that eliminates the need for external components. Sequans’ Monarch LTE-M/NB-IoT module incorporates a second-generation Monarch N chip platform purpose-built for utility meters, industrial sensors, and smart home devices.
Any IoT device can utilize Sequans’ IC via cloud-based NB-IoT networks within a few minutes. Image used courtesy of Sequans
This IC features an embedded security system that is said to optimize energy based on data traffic patterns. The supportive IoT module is cloud compatible and requires low power with a single-rail power supply of 2.5 V to 5.5 V for direct connections.
Sequans’ Monarch modules incorporate proprietary dynamic power management systems that have adaptive sleep and active mode to conserve power, extending the battery life to 15 years. The Monarch solution includes an evaluation kit that provides designers with reference designs, schematic layouts, and design files for PCB layouts.
e-peas and Sequans’ Self-Powered Solution
Combining e-peas AEM energy-harvesting IC with Sequans’ Monarch platform has led to a self-powered, cellular IoT connectivity solution that is battery-less. The new device will transfer energy that is harvested from e-peas’ AEM PV cells to storage—and then to the Sequans’ module, which will power a sensor measuring power, light, and humidity.
Didier Dutronc, head of Sequans’ IoT business unit, stated the importance of the company’s combined efforts with e-peas: “Energy harvesting technology is ushering in a new era where IoT devices will no longer have to run on batteries.”
Christian Ferrier, the chief marketing officer for e-peas added, “Not only do we show the viability of energy harvesting technology, but we show how IoT companies can build maintenance-free devices that can operate autonomously, which has a huge positive impact on sustainability, total cost of ownership, and device longevity.”