Ultra-Low Voltage Push-Pull Converter for Micro Energy Harvesting

Colalongo, L.; Leu, Derek; Richelli, Anna; Kovacs, Z.M.

doi:10.1109/tcsii.2020.2965551

Cited by 12 publications

(7 citation statements)

References 13 publications

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“…In the framework of state‐of‐the‐art IoT performance requirements, it can be concluded that such a μTEG is already in an operative range voltage for currently existing ultra‐low‐voltage DC–DC converters (requiring only a few millivolts). [ 71 ] Complementary, measured values of voltage can be substantially increased (in up to two orders of magnitude) by the integration of a heat sink (that essentially increases the temperature gradient across the NWs by improving heat rejection out of the suspended platform), which was successfully carried out by the authors in previous work for similar μTEGs. [ 25 ] Moreover, the integration of a heat sink helps to decouple the attainable Δ T from the thermoelectric active volume, that is, the NW array cross‐section.…”

Section: Resultsmentioning

confidence: 99%

Tuning the Thermoelectric Properties of Boron‐Doped Silicon Nanowires Integrated into a Micro‐Harvester

Gordillo

Estrada‐Wiese

Duque‐Sierra

et al. 2022

Adv Materials Technologies

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Section: Resultsmentioning

confidence: 99%

Tuning the Thermoelectric Properties of Boron‐Doped Silicon Nanowires Integrated into a Micro‐Harvester

Gordillo

Estrada‐Wiese

Duque‐Sierra

et al. 2022

Adv Materials Technologies

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“…The impact on the power output is also evident as observed in Figure 7b, where the maximum power output for a single platform (top row) raised up to 0.6 µW. Moreover, the series configuration (mid row) allows to reach V OC = 13.8 mV, which is sufficiently above the minimum level required for an ultra‐low voltage DC–DC converter to work (≈ 9 mV), [ 78 ] i.e., opens the way to use these devices to operate systems requiring higher voltages. In the case of the parallel configuration shown in the bottom row of Figure 7b, a maximum power of 1.25 µW is achieved.…”

Section: Resultsmentioning

confidence: 82%

Superior Thermoelectric Performance of SiGe Nanowires Epitaxially Integrated into Thermal Micro‐Harvesters

Gordillo

Sierra

Gadea

et al. 2023

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of trillions of delocalized sensors will require the development of robust micropower sources. [1] While primary batteries are nowadays the preferred solution, the current scenario cannot be extended much longer, as the exponentially growing number of connected devices require too complex logistics, both for their periodic replacement and disposal of such batteries. In this context, energy harvesting combined with small energy buffers (rechargeable batteries or capacitors) represents a more sustainable alternative to single-use batteries. [2][3][4] In particular, thermoelectric harvesters are solid-state devices capable of directly converting waste heat into electricity, with efficiencies in the range of 1%-10%. Among their main advantages, an absence of movable parts, high reliability, and the recently explored possibility of miniaturization make them promising candidates to power the IoT revolution. [5][6][7] The efficiency of a ThermoElectric (TE) system is measured using the so-called zT Figure of Merit, a dimensionless parameter that relates the main TE properties of the materials as zT = S 2 σT/κ, where S is the Seebeck coefficient, σ electrical conductivity, and κ its thermal conductivity. Although the thermoelectric effect is known since the 19 th century, currently, best-performing TE materials are still based on scarce, expensive, environmentally Semiconductor nanowires have demonstrated fascinating properties with applications in a wide range of fields, including energy and information technologies. Particularly, increasing attention has focused on SiGe nanowires for applications in a thermoelectric generation. In this work, a bottom-up vapour-liquidsolid chemical vapour Deposition methodology is employed to integrate heavily boron-doped SiGe nanowires on thermoelectric generators. Thermoelectrical properties -, i.e., electrical and thermal conductivities and Seebeck coefficient -of grown nanowires are fully characterized at temperatures ranging from 300 to 600 K, allowing the complete determination of the Figure-of-merit, zT, with obtained values of 0.4 at 600 K for optimally doped nanowires. A correlation between doping level, thermoelectric performance, and elemental distribution is established employing advanced elemental mapping (synchrotron-based nano-X-ray fluorescence). Moreover, the operation of p-doped SiGe NWs integrated into silicon micromachined thermoelectrical generators is shown over standalone and series-and parallel-connected arrays. Maximum open circuit voltage of 13.8 mV and power output as high as 15.6 µW cm −2 are reached in series and parallel configurations, respectively, operating upon thermal gradients generated with hot sources at 200 °C and air flows of 1.5 m s −1 . These results pave the way for direct application of SiGe nanowire-based micro-thermoelectric generators in the field of the Internet of Things.

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“…The performance of this converter is improved in both power efficiency, rise time, voltage output ripple, and maximum output voltage thanks to the reliance of the systems to small integrated inductors [29]. Another study in [30] presents an autonomous self-starting ultra-low-voltage DC-DC converter that begins operations at 9 mV, and its circuit is based on JFETs used in a zero-voltage switching push-pull Royer oscillator (a relaxation oscillator based on a center-tapped transformer), to operate at low voltages. This topology of oscillator is simple, has a low number of components, an easy transformer isolation, and at the same time it ensures reduced weight and size of the transformer.…”

Section: Energy Harvesting Sourcementioning

confidence: 99%

A Review of Fully Integrated and Embedded Power Converters for IoT

2021

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The Internet of Things (IoT) has found application in many components of implantable medical devices, wearable smart devices, monitoring systems, etc. The IoT devices are conventionally battery powered, even though, in several low power applications, they can also be powered using energy harvesting technology. Independently of the power sources (if batteries or environment), efficient and robust power converters must be designed to provide the small and distributed energy required by such IoT devices. This review paper will first provide an overview about the power consumption in IoT devices; second, it will discuss the most recent research and advance in the field of fully-integrated or embedded DC/DC converters, starting from high-performance integrated charge pumps or embedded inductive boost converters for specific harvesting sources (temperature, solar, and so on), to novel DC/DC converters for multiple energy sources.

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Ultra-Low Voltage Push-Pull Converter for Micro Energy Harvesting

Cited by 12 publications

References 13 publications

Tuning the Thermoelectric Properties of Boron‐Doped Silicon Nanowires Integrated into a Micro‐Harvester

Tuning the Thermoelectric Properties of Boron‐Doped Silicon Nanowires Integrated into a Micro‐Harvester

Superior Thermoelectric Performance of SiGe Nanowires Epitaxially Integrated into Thermal Micro‐Harvesters

A Review of Fully Integrated and Embedded Power Converters for IoT

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