Department: Electrical & Computer Engineering
Research Institute Affiliation: Center for Wearable Sensors
Faculty Advisor(s): Shadi A. Dayeh

Primary Student
Name: Ahmed Taha Elthakeb Youssef
Email: a1yousse@ucsd.edu
Phone: 858-534-6940
Grad Year: 2020

Living in the era of wearables, mutating high technologies with portable and flexible features that can be worn by a user ? animate or inanimate ? can lead to unprecedented applications that are only constrained by our imagination. With the evolution of the Internet of Things (IoT), wearables are playing a major role in connecting objects together. Leveraging advanced sensors and wireless modules, wearables enable personalized medicine by providing continuous monitoring of individual?s health through acquiring various vital health signs. Nevertheless, on top of the challenges that impede wearables to be compelling is sustainable source of power. Relying on batteries limits the performance of current commercial products to a fraction of the day after overnight charging. That is when imperious interest is given to energy harvesting approaches. Two factors though determine the decision of deploying energy harvesting technique within a particular technology: (a) the output power density to match the target application requirements, (b) the local usage environment. Accordingly, different wearable applications would require different harvesting/ design considerations. This study introduces novel monolithic integration scheme for efficient wearable electronics along with power sources by demonstrating process-compatible energy harvesting technique on the same wearable system on chip (SoC). Micro-wire solar cells have been fabricated on thin substrates acting as the energy harvesting module for powering up the overall wearable SoC. Extensive optimization has been carried out on both process and cell design levels including passivation studies, inserting optimum anti-reflective layers to enhance the light absorption, and studying the effect of microwire-array geometry parameters on the overall efficiency which currently stands at 15%. Compatible CMOS fabrication process has been developed using the same fabrication steps as those employed for microwire solar cells to build the integrated functional sensory circuits, which were tested to operate in the RF frequency domain. The overall system is then transferred to flexible substrate by embeding the designs in flexible polyimide layers. As system demonestration, we will present a telemetry circuit of integrated series solar cell modules for solar-powered wireless wearable system on chip.

Industry Application Area(s)
Energy/Clean technology | Materials | Semiconductor

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