DEADLINE: 15th April 2021
Description
- 36 months doctoral funding (October 2021 to September 2024)
- Keywords
High efficiency converter, cMUT transducer, piezoelectric generator, energy harvesting
- Profile ans skills required
The candidate must hold a Master's of Research degree or an engineering degree in one of the following specialties:
- Engineering Sciences with specialization in Electronics
- Engineering Sciences with specialization in Electrical Engineering
During his/her curriculum, the candidate will have had experience in
electronics, acoustics, signal processing and instrumentation. A good
knowledge of this field is essential to the success of the proposed
work. Complementary competence in one of the following areas would be
greatly appreciated:
- Software experience: PSpice or LTSpice; Matlab or Scilab; Octave
- Experience in instrumentation
- Project description
Capacitive Micro-machined Ultrasonic Transducers (cMUT) are
micro-capacitors (typically 50x50 µm2), one electrode of which is mobile
and the other fixed. When this capacitor is polarized and receives an
ultrasonic wave, the received mechanical energy is converted into
electrostatic energy. If a high number of micro-capacitors (typically a
few hundred) are combined in parallel, then the amount of energy
harvested is likely to be able to power electronic devices with very low
consumption. This area is commonly referred to as AET for Acoustic
Energy Transfer. This energy transfer, performed at ultrasonic
frequencies, can be done classically over a distance of a few
centimeters in biological tissues. AET thus appears to be a promising
avenue for powering Implanted Medical Devices (IMDs).
The electrostatic energy recovered by the cMUT receiver still needs
to be converted to a form suitable for the targeted electronic load.
This results in precise specifications in terms of shape and level of
voltage and current. An electronic converter must therefore be
interposed between the harvester and the load, and must have very low
power consumption. In addition, the cMUTs must be polarized by a DC
voltage at the beginning of the cycle, so a power source of a few µJ is
required to start operation. For this initial energy, one approach
consists of integrating a composite piezoelectric layer (here based on
ZnO nanowires) on the membrane of the cMUT.
In the framework of this thesis, the aim is to propose original
low-power conversion structures dedicated to cMUTs used for the
conversion of energy from ultrasonic waves in the range [40 kHz, 400
kHz]. Among the possible tracks, non-linear converters of SECE
(Synchronous Electric Charge Extraction) type, initially designed for
piezoelectric harvesters, also give good performances on electrostatic
harvesters. In addition, Totem-pole converters allow the voltage to be
raised in a similar way to SECE type converters, but with the advantage
of better efficiency by replacing the rectifier stage with the switching
cell. Particular care will be taken in the development of the control
electronics, which will have to be ultra low power consumption.
- References
1] G. V. B. Cochran et al., “Piezoelectric internal fixation
devices: A new approach to electrical augmentation of osteogenesis,” J.
Orthop. Res., vol. 3, no. 4, pp. 508–513, 1985.
[2] S. Ozeri et al., “Ultrasonic transcutaneous energy transfer using
a continuous wave 650 kHz Gaussian shaded transmitter,” Ultrasonics,
vol. 50, no. 7, pp. 666–674, 2010
[3] G. Poulin-Vittrant et al., “Challenges of low-temperature
synthesized ZnO nanostructures and their integration into nano-systems,”
Materials Science in Semiconductor Processing 91 (2019) 404-408
[4] EnSO, “Energy for Smart Objects,” financement ECSEL-JU 2016-2020, http://enso-ecsel.eu/
[5] S. Boisseau et al., “Microstructures électrostatiques de
récupération d’énergie vibratoire pour les microsystèmes,” Techniques de
l'ingénieur Innovations en énergie et environnement, RE160, 10 octobre
2010
[6] A. Morel et al., “A unified N-SECE strategy for highly coupled
piezoelectric energy scavengers,” Smart Materials and Structures, IOP
Publishing, 2018, 27 (8), pp.4002
[7] M. Perez et al., “Triboelectret-based aeroelastic flutter energy
harvesters,” Journal of Physics: Conference Series 773 (2016) 012021
[8] S. Jacques, C. Reymond, J.-C. Le Bunetel and G. Benabdelaziz,
'Comparison of the power balance in a Totem-Pole Bridgeless PFC topology
with several inrush current limiting strategies', Journal of Electrical
Engineering 72 (2021)
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