Functional neuroimaging is important for understanding brain health, assessing pathologies and guiding therapeutic interventions. Fundamental to neuroimaging is the neurovascular unit (NVU) which relates delivery and consumption of oxygen to neuronal activity. Dysfunction of NVU is associated with pathologies like stroke as well as dyspraxia. Estimating the cerebral metabolic rate of oxygen (CMRO2) that describes NVU activity, requires estimates of oxygen saturation in cerebral blood as well as cerebral blood flow (CBF). Functional magnetic resonance imaging (fMRI), the current gold standard for functional neuroimaging, is expensive, lacks portability and provides only surrogate estimates of CBF. Recent advancements in diffuse optics and functional near-infrared imaging paved the way for non-invasive neuroimaging using diffuse optical techniques. Development of high-density diffuse optical tomography (HDDOT) for imaging oxygen saturation and high-density speckle contrast optical tomography (HDSCOT) for measuring CBF have enabled imaging at spatial resolutions comparable to fMRI. However, combining independently obtained CBF and oxygenation values to compute CMRO2 leads to artifacts and systematic errors. A hybrid imaging modality providing more accurate CMRO2 quantification via co-dependent estimates of oxygen saturation and CBF is needed to tap into potential of optical neuroimaging to paradigms like continuous cerebral monitoring in clinical and naturalistic settings. In this project, we propose development of algorithmic frameworks for such a modality i.e., hybrid HDSCOT/DOT for concurrent estimation of blood flow and oxygenation through (i) development of an inversion algorithm for hybrid imaging, (ii) development of frameworks for selection of optimal acquisition configuration and (iii) numerical and experimental validation of the developed frameworks. This research will closely follow ongoing hardware and system development in the Medical Optics group at ICFO.

Growing technological and societal advances have accelerated the energy requirements. To meet energy demands, reliance on fossil fuels has led to catastrophic changes in the environment and global climate due to carbon emissions. Renewable energy sources offer excellent ways to meet energy demands in addition to reducing carbon emissions. Although solar energy is most abundant on Earth, its variability across locations and times makes it unreliable for consistent energy supply. Thus, efficient energy storage technologies are also essential for a sustainable future. Perovskite solar cells (PSCs) have emerged as a highly efficient technology for converting solar energy into electricity owing to their remarkable properties, while hydrogen (H2) is gaining recognition as the ultimate source of green fuel. A photovoltaic-electrochemical (PV-EC) arrangement offers an excellent solution for sustainable solar energy conversion and storage. However, previously reported PV-EC systems employ two or more PV devices or solar cells connected in series to afford enough voltage (1.7 V) for H2 production. This proposal aims to ingeniously design a compact PV-EC device, using a single-junction PSC providing sufficient voltage and employing this to an EC cell for H2 production. The main objectives are: 1) To fabricate PSC using carefully selected perovskite materials with optimally wide bandgap and apply passivation strategies to achieve a high voltage of >1.5 V at maximum power point (MPP). 2) To further enhance the voltage up to a remarkable value of ~1.7 V at MPP, specifically designed photonic nanostructures will be incorporated into the PSCs for reducing the Boltzmann loss (mismatch in incident and emitted lights). 3) To assemble a PV-EC compact device utilizing the developed PSC for H2 production through water splitting. This research will motivate the incorporation of nanophotonic structures in other PV technologies and facilitate high voltages for energy storage applications.