The thesis deals with power harvesting sensors as a source of energy. As the power requirements for microelectronics decreases the environmental energy sources become more perspective. In a few last years batteries reach a higher capacity but there is still problem with their replacement. Power harvesting sensors appears as a good solution for powering microelectronics.

The great popularity of portable, wearable, and implantable smart electronics has intensively boosted the development of flexible miniaturized power supplies. Owing to the fast charge/discharge capability, high power delivery, long cycling lifetime, easy fabrication and integration, flexible in-plane micro-supercapacitors (FPMSCs) are of significance as the micropower sources for the next-generation flexible on-chip electronics. In this review, we provide a comprehensive overview about FPMSCs and discuss the recent advances in their fabrication and applications. Particular emphasis is put on the emergent device fabrication technologies of FPMSCs, including deposition techniques, coating strategies, etching methods, and printing technologies. Moreover, we highlight the unique applications of FPMSCs in constructing smart responses and self-powered integrated systems in terms of multifunctional operation modes. Finally, the remaining challenges regarding flexibility, performance improvement, smart response, and microdevice integration of FPMSCs are discussed, which will stimulate further research in this thriving field.

<p dir="ltr">Ultra-scaled, always-on, smart, wearable and implantable (WI) therapeutic platforms define the research frontier of modern personalized medicine. The WI platform integrates real-time sensing with on-demand therapy and is ideally suited for real-time management of chronic diseases like diabetes. Traditional blood tracking methods, such as glucometers, are insufficient due to their once-in-a-while measurements and the imprecision of insulin injections, which can lead to severe complications. To address these challenges, researchers have been developing smart and minimally invasive microneedle (MN) components for pain-free glucose detection and drug delivery, potentially functioning as an "artificial pancreas". Inspired by natural body homeostasis, these platforms must be accurate and responsive for immediate corrective interventions. However, artificial MN patches often have slow readings due to factors like MN morphology and composition that remain poorly understood, hindering their optimization and integration into real-time monitoring devices. Despite extensive, iterative experimental efforts worldwide, a holistic framework incorporating the interaction between MN sensing and therapy with fluctuating natural body functions is missing. In this thesis, we propose a generalized framework for glycemic management based on the interaction between biological processes and MN-based operations. The results, incorporating theoretical insights from the 1960s and recent advancements in MN technology, are platform-agnostic. This generality offers a unique template to interpret experimental observations, justify the recent introduction of drugs like GLP-1 cocktails, and optimize platforms for accurate and fast disease management. </p>

Traditional fabrication methods used to manufacture biosensors for physiological, therapeutics, or health monitoring purposes are complex and rely on costly materials, which has hindered their adoption as single-use medical devices. The development of a new kind of wearable and implantable electronics relying on inexpensive materials for their manufacturing will pave the way towards the ubiquitous adoption of sticker-like health tracking devices.<div>One of growing and most promising applications for biosensors is the continuous health monitoring using mechanically soft, stretchable sensors. While these healthcare devices showed an excellent compatibility with human tissues, they still need highly trained personnel to perform multi-step, prolonged fabrication for several functioning layers of the device. In this dissertation, I propose low-cost, scalable, simple, and rapid manufacturing techniques to fabricate multifunctional epidermal and implantable sensors to monitor a range of biosignals including heart, muscle, or eye activity to characterizing of biofuids such as sweat. I have also used these devices as an implant to provide heat therapy for muscle regeneration and optical stimulation of neurons using optogenetics. These devices have also combined with those of triboelectric<br>nanogenerators to realize self-powered sensors for monitoring imperceptible mechanical biosignals such as respiratory and pulse rate.</div><div>Food health and safety has also emerged as another important frontier to develop biosensors and improve the human health and quality of life. The recent progresses on detecting microbial activity inside foods or their packages rely on development of highly functional materials. The existing materials for fabrication of food sensors, however,<br>are often costly and toxic for human health or the environment. In this dissertation, I proposed biocompatible food sensors using protein/PCL microfibers to reinforce the protein microfibrous structure in humid conditions and exploit their excellent hygroscopic properties to sense biogenic gas, as an indicator for early detection of food spoilage. Finally, my battery-free food sensors are capable of monitoring food safety with no need of extra measurement devices. Collectively, this dissertation proposes cost-effective solutions to solve human health issues, enabled by developing low-cost, functional materials and exploiting simple fabrication techniques.<br></div>