SARELA: Self-powered system with thermoelectric and photovoltaic energy harvesting

Implanted medical devices such as pacemakers, cardiac defibrillators, cochlear or retinal implants have proven to be extremely useful in clinical practice. However, despite efforts in low power design, power consumption is still a critical issue. Therefore, the development of alternatives to conventional batteries is a technological challenge of enormous social and economic implications. In this sense, this research project proposes the development of a dual energy harvesting system collecting both thermoelectric and photovoltaic energy from the environment to power implantable devices efficiently. For this purpose, a special emphasis on issues such as biocompatibility, size and power consumption is done .

The system consists of two power generating modules. On the one hand, one thermoelectric module capable of generating an output voltage in response to temperature differences in the human body and, secondly , a solar cell array constituted by a array of micro photodiodes which, in turn, may be reconfigured to operate in imaging mode in applications such as retinal prosthesis. The micro solar cell will be integrated in a CMOS chip also including circuitry for the conversion and management of the collected energy. Finally, a system demonstrator will be developped to prove the efficiency of the energy harvesting.

Objectives

A priori estimation of the energy harvesting expectatives of the thermoelectric and photovoltaic elements using commercial simulators.
Fabrication of the thermoelectric generators.
Experimental characterization of the thermoelectric generators.
Design of the micro solar cell and the chip interface to use the harvested energy.
Experimental characterization of the chip.