Figure 4 - uploaded by Ana Carretero Pérez
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Voltage in the capacitor with solar energy (blue trace). Thresholds refer to the working limit. The cross between the vertical line (grey trace, 30 minutes) and the horizontal line (orange trace, 2.7 V) is when the system starts to work.

Voltage in the capacitor with solar energy (blue trace). Thresholds refer to the working limit. The cross between the vertical line (grey trace, 30 minutes) and the horizontal line (orange trace, 2.7 V) is when the system starts to work.

Source publication
Article
Full-text available
In this work, we present autonomous active tags. The power sources of these active tags employ energy harvesting techniques, specifically, solar and mechanical techniques. The integration of these techniques, and the storage of the energy obtained with a supercapacitor, converts the active tag into an autonomous device. These tags work in a low pow...

Contexts in source publication

Context 1
... first check the solar energy and then the mechanical energy. The tag turns on when the voltage in the supercapacitor reaches 2.7 V. Figure 4 shows the time it takes for the solar module to charge the supercapacitor on a sunny day. The vertical grey line in 30 min and the horizontal orange line in 2.7 V indicate the time and voltage, respectfully, needed to turn on the device. ...
Context 2
... for the final device, it is important to minimize or eliminate the hours in which the device is in a shady zone. However, the limiting case of solar energy comes from the voltage drop during the night, as can be checked in Figure 4. This means that if we want the device to stay on continuously, it will be important to characterize those conditions in future implementations because this application is related to an enclosed framework, where the sun is needed for a positive energy balance. ...

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Citations

... These sensors are still difficult to develop due to the power and space limitations, accessibility problems, and the ubiquitous automotive need for reliability. All this points to the use of energy harvesting (EH) and wireless power transfer (WPT) where possible [3]- [6]. Studies already published have highlighted the need to develop methods and strategies to be adopted according to the type of application to be implemented. ...
Conference Paper
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This paper presents three different techniques for efficiently powering an energy-autonomous wireless sensor (EAWS) through both energy harvesting (EH) and RF wireless power transfer (WPT). The aim of the paper is to provide effective strategies and techniques to reduce, as far as possible, the cost of wiring of the automotive production process due to the continuous and constant increase in the use of sensors. The techniques employ a highly integrated state-of-the-art, ultra-low power 2.5 µW system-on-chip (SoC) system, designed for multi-source RF wireless energy harvesting and power transfer and are designed with the goal of minimizing and, where possible, eliminating the costly maintenance required by conventional wireless sensors. Specific examples are reported that define both the aspects of convenience and the limits of use. Index Terms-automotive, energy harvesting, radio frequency, wireless power transfer, wireless battery charger, lithium ion battery, wireless sensor networks.