Ultra-Low-Power Circuits for Intermittent Communication

Torrisi, Alessandro; Yıldırım, Kasım Sinan; Brunelli, Davide

doi:10.3390/jlpea12040060

Cited by 2 publications

(2 citation statements)

References 34 publications

(64 reference statements)

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“…The final choice depends however, on the use case of the node and sometimes on the availability of the commercial products. Similarly, energy could be saved in the choice of the type of sensors and wake-up techniques needed to trigger the cold start of the node, the use of energy aware techniques [52]. Here also, the requirements the application at hand are important.…”

Section: Touch Detectionmentioning

confidence: 99%

Energy Autonomous Wireless Sensing Node Working at 5 Lux from a 4 cm2 Solar Cell

Meli

Favre

Maij

et al. 2023

JLPEA

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Harvesting energy for IoT nodes in places that are permanently poorly lit is important, as many such places exist in buildings and other locations. The need for energy-autonomous devices working in such environments has so far received little attention. This work reports the design and test results of an energy-autonomous sensor node powered solely by solar cells. The system can cold-start and run in low light conditions (in this case 20 lux and below, using white LEDs as light sources). Four solar cells of 1 cm2 each are used, yielding a total active surface of 4 cm2. The system includes a capacitive sensor that acts as a touch detector, a crystal-accurate real-time clock (RTC), and a Cortex-M3-compatible microcontroller integrating a Bluetooth Low Energy radio (BLE) and the necessary stack for communication. A capacitor of 100 μF is used as energy storage. A low-power comparator monitors the level of the energy storage and powers up the system. The combination of the RTC and touch sensor enables the MCU load to be powered up periodically or using an asynchronous user touch activity. First tests have shown that the system can perform the basic work of cold-starting, sensing, and transmitting frames at +0 dBm, at illuminances as low as 5 lux. Harvesting starts earlier, meaning that the potential for full function below 5 lux is present. The system has also been tested with other light sources. The comparator is a test chip developed for energy harvesting. Other elements are off-the-shelf components. The use of commercially available devices, the reduced number of parts, and the absence of complex storage elements enable a small node to be built in the future, for use in constantly or intermittently poorly lit places.

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Section: Touch Detectionmentioning

confidence: 99%

Energy Autonomous Wireless Sensing Node Working at 5 Lux from a 4 cm2 Solar Cell

Meli

Favre

Maij

et al. 2023

JLPEA

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“…In such configurations, operation is possibly intermittent, and the operation duty cycle is the factor that characterizes how unbalanced the load power consumption from the available power and energy delivered by the harvesting function may be. Intermittency is taken into account for optimizing electronic circuits or communication strategies [5] and benefits to the rate of operation. Namely, the energy-harvesting function has to pump electrical energy into a capacitor until a sufficient level is reached that enables the operation of the IoT system for a certain amount of time.…”

Section: Introductionmentioning

confidence: 99%

Microbial Fuel Cell as Battery Range Extender for Frugal IoT

Berlitz,

Pietrelli,

Mieyeville

et al. 2023

Energies

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The simplest DC/DC converter for supplying an Internet-of-Things device is definitely a switched-capacitor converter. The voltage from a mere 1.2 V battery may be stepped up to 2 V. A quite large operating frequency is required in order to reach the smallest possible output impedance value of the DC/DC converter. The overall efficiency is then limited even more so if the power area density of the system should be large. The article details how a microbial fuel cell may substitute one capacitor in the switched-capacitor converter, achieving a better efficiency at a much lower operating frequency. In that perspective, the microbial fuel cell acts as a kind of battery range extender. Some limitations exist that are discussed. A simple converter is experimentally evaluated to support the discussion. Substituting a microbial fuel cell inside a 100 μW switched-capacitor converter compensates for losses in the order of 5% of efficiency. Moreover, the microbial fuel cell extends the lifespan of the battery, as 1.6 V output voltage is still possible when the battery voltage drops to 0.8 V. More than 94% efficiency is measured for a range of output power between 100 μW and 1 mW, which is sufficient to address a lot of frugal IoT applications.

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Ultra-Low-Power Circuits for Intermittent Communication

Cited by 2 publications

References 34 publications

Energy Autonomous Wireless Sensing Node Working at 5 Lux from a 4 cm2 Solar Cell

Energy Autonomous Wireless Sensing Node Working at 5 Lux from a 4 cm2 Solar Cell

Microbial Fuel Cell as Battery Range Extender for Frugal IoT

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