Soft and flexible bioelectronic micro-systems for electronically controlled drug delivery

The concept of targeted and controlled drug delivery, which directs treatment to precise anatomical sites, offers benefits such as fewer side effects, reduced toxicity, optimized dosages, and quicker responses. However, challenges remain to engineer dependable systems and materials that can modulate host tissue interactions and overcome biological barriers. To stay aligned with advancements in healthcare and precision medicine, novel approaches and materials are imperative to improve effectiveness, biocompatibility, and tissue compliance. Electronically controlled drug delivery (ECDD) has recently emerged as a promising approach to calibrated drug delivery with spatial and temporal precision. This article covers recent breakthroughs in soft, flexible, and adaptable bioelectronic micro-systems designed for ECDD. It overviews the most widely reported operational modes, materials engineering strategies, electronic interfaces, and characterization techniques associated with ECDD systems. Further, it delves into the pivotal applications of ECDD in wearable, ingestible, and implantable medical devices. Finally, the discourse extends to future prospects and challenges for ECDD

Resilience of an embedded architecture using hardware redundancy

In the last decade the dominance of the general computing systems market has being replaced by embedded systems with billions of units manufactured every year. Embedded systems appear in contexts where continuous operation is of utmost importance and failure can be profound. Nowadays, radiation poses a serious threat to the reliable operation of safety-critical systems. Fault avoidance techniques, such as radiation hardening, have been commonly used in space applications. However, these components are expensive, lag behind commercial components with regards to performance and do not provide 100% fault elimination. Without fault tolerant mechanisms, many of these faults can become errors at the application or system level, which in turn, can result in catastrophic failures. In this work we study the concepts of fault tolerance and dependability and extend these concepts providing our own definition of resilience. We analyse the physics of radiation-induced faults, the damage mechanisms of particles and the process that leads to computing failures. We provide extensive taxonomies of 1) existing fault tolerant techniques and of 2) the effects of radiation in state-of-the-art electronics, analysing and comparing their characteristics. We propose a detailed model of faults and provide a classification of the different types of faults at various levels. We introduce an algorithm of fault tolerance and define the system states and actions necessary to implement it. We introduce novel hardware and system software techniques that provide a more efficient combination of reliability, performance and power consumption than existing techniques. We propose a new element of the system called syndrome that is the core of a resilient architecture whose software and hardware can adapt to reliable and unreliable environments. We implement a software simulator and disassembler and introduce a testing framework in combination with ERA’s assembler and commercial hardware simulators

Alleviating Through-Silicon-Via Electromigration for 3-D Integrated Circuits Taking Advantage of Self-Healing Effect

International audienceThree-dimensional integration is considered to be a promising technology to tackle the global interconnect scaling problem for terascale integrated circuits (ICs). Three-dimensional ICs typically employ through-silicon-vias (TSVs) to vertically connect planar circuits. Due to its immature fabrication process, several defects, such as void, misalignment, and dust contamination, may be introduced. These defects can significantly increase current densities within TSVs and cause severe electromigration (EM) effects, which can degrade the reliability of 3-D ICs considerably. In this paper, we propose an effective framework to mitigate EM effect of the defective TSV. At first, we analyze various possible TSV defects and their impacts on EM reliability. Based on the observation that EM can be significantly alleviated by self-healing effect, we design an EM mitigation module to protect defective TSVs from EM. To guarantee EM mitigation efficiency, we propose two defective TSV protection schemes, i.e., neighbor sharing and global sharing. Experimental results show that the global-sharing scheme performs the best and can improve the EM mean time to failure by more than $70\times$ on average with only 0.7% area overhead and less than 0.5% performance degradation compared with naked design without any EM protection

Rational Design of Flexible and Stretchable Electronics based on 3D Printing

Flexible and stretchable electronics have been considered as the key component for the next generation of flexible devices. There are many approaches to prepare the devices, such as dip coating, spin coating, Mayer bar coating, filtration and transfer, and printing, etc. The effectiveness of these methods has been proven, but some drawbacks cannot be ignored, such as lacking pattern control, labor consuming, requiring complex pretreatment, wasting conductive materials, etc. In this investigation, we propose to adopt 3D printing technology to design flexible and stretchable electronics. The objective is to rationally design flexible and stretchable sensors, simplify the preparation process, form the sample with the complex desirable patterns, and promote the performance of the samples. The dissertation comprises of three major parts: water-induced polymer swelling and its application in soft electronics, utilizing 3D printing to transfer conductive layer into elastomer for building soft electronics, and 3D printing of functional devices. In the first part, we developed the soft electronics with wrinkled structure via 3D printing and water-induced polymer swelling, which can avoid some disadvantages in conventional method, e.g., pre-stretching and organic solvent-induced polymer swelling, including mechanical loss, negative effect to human health, and unidirectionally response to external deformation. Water-induced polymer swelling was achieved by introducing soluble particles into silicone matrixes and soaking the polymer composites in aqueous solution. We have investigated the characteristics and mechanisms of water-induced polymer swelling. Then, the conductive materials were deposited on the swollen sample to form the desired wrinkled structures for stretchable sensors. Furthermore, a dopamine layer was adopted to enhance the adhesion of matrix and conductive layer. The improvement was a key enabler to achieve superior electrical properties of 3D printed stretchable sensors for long-term cyclic stretching. We have demonstrated a series of human motion detection by using these stretchable strain sensors. Another part is designing flexible electrodes with desirable complex pattern by transferring a conductive layer into soft substrates during a 3D printing process. Taking advantage of extrusion pressure and polymer adhesion, the thin conductive layers were embedded into the printed polymer patterns, which can achieve conductive flexible electronics with desirable complex patterns. High-quality transfer has been achieved through adjusting conductive layer thickness, nozzle-to-substrate distance, and printing parameters, etc. Moreover, various printing patterns were created, and their properties were exhibited. The stretchable sensors showed an outstanding stress-strain relationship and electrical response to external deformations. The third part is about 3D printing of functional devices. In the collaborated study, the drug particles were introduced into silicone matrix to prepare the drug-eluting devices. When water molecules transported into the silicone matrix, the loaded drug particles decomposed and released nitric oxide (NO) enabling antibacterial properties. It is noted that 3D printing is creatively employed to form the desirable patterns. We also observed a self-wiring effect in the printing process, i.e., the printed device is covered by a drug-free layer due to the diffusion of a low viscosity silicone component during printing, which can be utilized to prevent drug release bursts and to form a gradient drug-loaded device. The printed samples showed a sustainable NO release and good antibacterial property. Furthermore, the water-induced polymer swelling was possible to be used as actuator in humidity environment. There are some highlights deserving emphasis in the dissertation. Firstly, the water-induced polymer swelling is proposed to develop the flexible and stretchable electronics. The findings have a wide potential application. Additionally, a drug-eluting polymer device with a drug-loaded bulk and a drug-free coating is prepared via leveraging self-wiring effect in 3D printing. The structure can regulate the drug release rate. On the other hand, the additive manufacturing platform offers unique opportunities to produce drug-eluting silicone devices in a customized manner. Finally, 3D printing is employed to encapsulate the conductive layers to achieve the flexible electronics with patterned structure and high performances. The facile and effective approach provides a distinctive view in advancing the development of stretchable electronics

Modern Applications of Novel Electroless Plating Techniques

This dissertation is composed of three distinct but closely related topics on the electrochemical metallization of substrates. The first topic solves the longstanding problem of galvanic corrosion in connection with exploiting the advantageous properties of magnesium {Mg} alloys and is of vital interest to the automotive and aerospace sectors. The second topic provides a new approach to the selective electroless metallization of silicon {Si} in connection with solar cells and other electronic devices. The third topic details a novel method of metal thin film formation using wet chemistry techniques which allow for the deposition of alternating metal layers of different and similar nobility from a single electrolyte. Future possible avenues of investigation are suggested for each of the three topics. The resolution of the galvanic corrosion issue, as presented within herein, is based on the direct electroless deposition of metal thin films less active than the Mg alloy substrates. Claddings of copper {Cu}, nickel boron {Ni-B}, and phosphorous {P} alloys including: nickel {Ni-P}, cobalt {Co-P}, nickel-zinc Ni-Zn-P}, and other ternary alloys, were successfully deposited directly on Mg alloy surfaces. The electroless coating of Mg alloys was accomplished using minimal pre-treatments and made use of the naturally active properties of Mg-based substrates. Qualitative measures of the corrosion resistance of Ni-Zn-P coatings on Mg alloys demonstrated superior resistance to galvanic corrosion compared to uncoated surfaces. The selective electroless metallization of Si is accomplished with the selective removal of the silicon oxide {SiO x } by means of mechanical scribing thereby exposing Si. The exposure of Si provides a catalytic surface for the electroless deposition of gold {Au}, and silver {Ag}, and other metals. The mechanical scribing provides an inexpensive avenue for the selective metallization of Si for solar cells. The novel method of depositing alternating metal layers of both different and similar nobility is achieved by combining electroplating and electroless deposition within a single electrolyte. The technique, termed here hybrid electro-electroless deposition (HEED), provides coatings previously unobtainable using wet electrochemical techniques. The application of HEED is of interest for the provision of sacrificial coatings on Mg alloys for corrosion protection within the transportation sector

Exploring the properties of liquid metals in electrochemical systems

Low melting point post-transition metals and alloys, dubbed as liquid metals (LMs), have emerged as group of soft yet conductive materials with remarkable physical and chemical properties. The enigmatic features of LMs originate from their deformable and electron-rich core as well as their atomically smooth and chemically active interface. These features can offer opportunities for designing novel electrochemical systems with improved performance and applicability. Despite the great potential, LM-based electrochemical modules are at nascent stage and the fundamental knowledge regarding electric field-induced events at LMs/electrolyte interfaces is still elusive. The present thesis focuses on the incorporation of LMs and LM-based materials in different electrochemical set-ups. The outcomes showcase the capability of LMs for materials synthesis, biosensing, and alloy processing via electrochemical routes. In chapter 3 of this thesis, the author focuses on the exploitation of autogenous interfacial potential generated on gallium and indium eutectic alloy, EGaIn, to drive a galvanic reduction reaction (GRR). It is revealed that EGaIn could effectively reduce graphene oxide (GO) in different configurations to produce monolayers and thick membranes of reduced GO (rGO) as well as LM droplets covered with a shell of rGO flakes. In chapter 4, the core-shell structures of LM-rGO, synthesized via GRR, were electrochemically characterized through their incorporation as a modifier to electrochemical interfaces. The author revealed that incorporation of the LM-based modifier results in improved charge transfer kinetics, higher electroactive surface area, and lower resistance. The remarkable electrochemical performance of LM-rGO particles were exploited for selective biosensing of dopamine using both paper-based devices and conventional electrochemical set-ups. In chapter 5, droplets of a gallium- and an indium-based LM eutectic alloys were electrochemically diagnosed to explore interfacial events occurring at LM/electrolyte interface. The author showed that upon surface perturbation by a cathodic voltage, solute elements tend to segregate at the interface according to their energy levels. The electrolyte solution was observed to have a substantial effect on the composition of segregated domains. Collectively, this PhD research demonstrates opportunities for designing novel electrochemical systems based on LMs and provides valuable insights into voltage-dependent behaviour of LMs, which can potentially contribute to the advancement of scientific fields such as materials processing, energy, and sensors

Dynamic Nanophotonic Structures Leveraging Chalcogenide Phase-Change Materials

Chip-scale nanophotonic devices have the potential to enable next-generation imaging, computing, communication, and engineered quantum systems with very stringent performance requirements on size, power, integrability, stability, and bandwidth. The emergence of meta-optic devices with deep subwavelength features has enabled the formation of ultra-thin flat optical structures to replace bulky conventional counterparts in free-space applications. Nevertheless, progress in meta-optics has been slowed due to the passive nature of existing devices and the urgent need for a reliable, fast, low-power, and robust reconfiguration mechanism. In this research, I devised a new material and device platform to resolve this challenge. Through detailed theoretical design, nanofabrication, and experimental demonstration, I demonstrated the unique features of my proposed platform as an essential building block of truly scalable adaptive flat optics for the active manipulation of optical wavefronts. One of the key attributes of this research is the integration of CMOS-compatible materials for the fabrication of passive devices with phase-change materials that provide the largest known modulation of the index of refraction upon stimulation with an optical or electrical signal. A unique selection of phase-change materials for operation in the near-infrared and visible wavelengths has been made, followed by developing the optimum deposition and fabrication processes for the realization of nanophotonics devices that integrate these functional materials with semiconductor and plasmonic materials. A major breakthrough in this process was the design and realization of integrated electrical stimulation circuitry with far better performance compared to existing solutions. Using this platform, I experimentally demonstrated the first electrically tunable meta-optic structure for fast optical switching with a high contrast ratio and dynamic wavefront scanning with a large steering angle. This is a major achievement as it essentially allows the engineering of a desired optical wavefront with fast reconfigurability at low power consumption. In an independent work, I demonstrated, for the first time, a nonvolatile meta-optic structure for high-resolution, wide-gamut, and high-contrast microdisplays with added polarization controllability and the possibility of implementation on a flexible substrate. Further features of this metaphotonic display include: 1) full addressability at the microscale pixel via fast electrical pulses; 2) super-resolution pixels with controllable brightness and contrast; and 3) a wide range of colors with high saturation and purity. Lastly, for the first time, I realized a hybrid photonic-plasmonic meta-optic platform with active control over the spatial, spectral, and temporal properties of an optical wavefront. This is a major achievement as it essentially allows the engineering of a desired optical wavefront with fast reconfigurability at low power consumption. These demonstrations are now being pursued in different directions for novel systems for imaging, sensing, computing, and quantum applications, just to name a few.Ph.D

Reliability Abstracts and Technical Reviews January-December 1969

No abstract availabl

Strategy design of youth science and innovation environment for modern engineer training

Сборник содержит труды участников Международной молодежной научной школы "Методология проектирования молодежного научно-инновационного пространства как основа подготовки современного инженера". Включает материалы семинара, мастер-класса, доклады студентов и молодых ученых, представленные на секциях "Развитие энергоэффективных технологий как залог повышения экономического потенциала страны", "Единство традиций и инноваций как основа развития современной инженерной науки", "Инновационные тенденции модернизации инженерного дела в условиях глобализации". Сборник представляет интерес для студентов, аспирантов, молодых ученых, преподавателей в области естественных нау