Thierry Djenizian

Developing bioresorbable energy sources that eliminate the need for secondary surgery for device removal remains a major challenge in resorbtronics. In this work, we present an alternative fabrication strategy for new bioresorbable quasi‐solid Na‐ion batteries using Mo or Mg thin films as current collectors. The assembled batteries were characterized using scanning electron microscopy, spectroscopic techniques including X‐ray photoelectron spectroscopy, physicochemical, and electrochemical characterization techniques. Results demonstrate that the choice of current collector strongly influences electrochemical performance. Mo‐based batteries delivered a discharge capacity of 6.8 mAh cm ^{− 2} at a C/2 rate, approximately twice that of Mg‐based counterparts whose performance is limited by oxidation reactions. Moreover, Mo‐based batteries exhibited stable cycling with 86% capacity retention after 100 cycles at 2C. In vitro cytotoxicity assays showed cell viability above the 70% threshold indicating that the tested materials are non‐cytotoxic according to ISO 10993 guidelines. Implantation studies confirmed safe degradation of Mo‐based batteries supported by in vivo monitoring of animal health behavior and ex vivo organ analyses, including organ weight, ALT measurements, and histological evaluation of skin at the implantation site after three months. Additionally, the operational lifetime of implanted batteries can be tuned from days to months by controlling encapsulation layer thickness.

Silicon is a promising anode material for next-generation lithium-ion batteries (LIBs) due to its high theoretical capacity. However, its practical use is hindered by significant volume expansion during charge cycles, which causes poor cycling stability. Intense pulsed light technology offers a solution through rapid, selective heating, enabling nanoscale transformations without damaging substrates. Here, a scalable approach for creating silicon patterns on polymer foils and converting them into nanoscale composite layers under ambient conditions is presented. The use of inkjet printing in conjunction with intense Pulsed Light treatment is demonstrated to generate localized temperatures in excess of 1,940 °C within milliseconds, whilst maintaining the integrity of the polymer substrate. This rapid heating method induces local carbonization of the polymer, thereby converting the Si nanoparticles into a new silicon carbide (SiC) embedded in a few-layer graphene composite electrode. The resulting heterostructure anode exhibits excellent electrochemical performance, improved cycling stability, and enhanced rate capability, positioning it as a promising binder-free silicon anode for next-generation lithium-ion batteries.

In this work, an alternative fabrication process is implemented to fabricate a bioresorbable Na‐ion battery showing excellent electrochemical performance (discharge capacity of 5.1 mAh cm⁻²) and no toxicity after being disintegrated under in vivo conditions. Solely composed of biocompatible materials, the proposed all‐solid‐state rechargeable battery implanted under the skin is capable of disintegrating safely. The operating days and lifetime of this novel energy storage system are evidenced that after being implanted in artificial skin can be finely controlled by tuning the thickness of the encapsulation layer, rendering possible the design of “on‐demand” bio‐eliminable batteries that may operate days or several weeks. The toxicity tests and the lack of organ damage performed by ex vivo analyses after 3 months confirmed the safety of the approach. In addition, wireless recharge of the battery is demonstrated through the skin using an inductive charger to establish the proof‐of‐concept. Preliminary tests revealed that wireless recharge of the subcutaneous implanted battery is achieved in 30 min, and that recharge remains possible in 1 h for deeper implanted batteries. The high versatility of the concept is definitely appealing to address the various needs of the temporary medical device market.

Self‐organized TiO₂ nanotube (TNT) layers with different thicknesses are prepared by anodization of Ti foils and then characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), and electrochemical techniques to be used as potential anodes for Li‐ion microbatteries. Electrochemical behaviors between 1 and 190 μm thick electrodes, which are the thickest ever studied layers as electrode, have been evaluated by cyclic voltammetry (CV) and chronopotentiometry at various kinetics. The highest areal capacity is obtained for TNT layers of 190 μm providing an initial discharge capacity of ≈5.3 mAh cm⁻² at C/10. At faster kinetics, the ≈80 μm thick TNT layer reveals the best electrochemical behavior by offering 256 μAh cm⁻² at 5 C and a good stability for 200 cycles at C/5. The influence of the increasing thickness on the electrochemical performance at fast rates can be attributed to the uncomplete reaction of TNT layers with Li ions and the enhancement of the formation of a solid electrolyte interphase. It is also shown that a very thick electrode is not able to sustain long and very fast cycles due to the mechanical deformations occurring during the successive insertion/extraction of Li ions.

Silicon emerges as a candidate for advancing lithium ion batteries with important roles in various applications ranging from portable electronics to electric vehicles. However, despite its theoretical capacities silicon faces challenges such as unstable cycling and limited rate performance. This thorough review examines developments in improving the electrochemical performance of silicon and graphene within the context of lithium ion batteries. The focus lies on strategies for designing and synthesizing composite materials that incorporate silicon particularly when combined with graphene. Structural aspects like particle size, morphology and porosity are carefully optimized to harness the potential of silicon based anodes and graphene. The review highlights the effects resulting from these tailored design approaches, including key factors such as capacity retention, cycling stability and rate capability of the resulting anode materials. By exploring these design paradigms this review offers a comprehensive perspective on the transformative capabilities of silicon, graphene and silicon/graphene composites. It does not highlights recent advancements but also outlines future directions for innovation and practical applications. This compilation of progress contributes to the understanding of how silicon based anodes, in lithium ion batteries have evolved from small‐scale implementations to catalyzing advancements in energy utilization.

The development of integrated micro‐power sources is mainly driven by innovative investigations in materials chemistry, battery designs, and microfabrication processes. Here, a new technique is described for the development of coaxial wire‐shaped Li‐ion batteries by successfully adopting the unidirectional helical winding method starting from a twisted Cu fabric. Such a coaxial wire battery is examined by scanning electron microscopy and characterized by electrochemical techniques. These investigations reveal that the proposed approach is definitely suitable for achieving wire batteries showing high energy storage capacity while being highly flexible and stretchable without compromising the whole electrochemical performance even under mechanical deformations. The full cell based on the Li ₄ Ti ₅ O ₁₂ /LiCoO ₂ system delivers an outstanding linear capacity of 137 µAh cm ⁻¹ at a 0.1C rate with nearly 100% coulombic efficiency and is further capable of being operated at various kinetics. It is also shown that such a coaxial wire battery can be used to power different electronic devices, which is of significance for the development of autonomous wearable applications like electronic textiles

Increasing surface area between electrodes and electrolytes drastically has proven to improve electrochemical performances of microbatteries. 3D surface enhancement owing to the design of micropillar electrodes has permitted to fulfill this need while maintaining the same footprint area. Lithium nickel manganese oxide (cathode) and Lithium titanate (anode) micropillars with different sizes are successfully fabricated on aluminum foils by laser ablation technique and are then separated by a polymer electrolyte to form stretchable lithium‐ion microbatteries. The electrochemical performance of full batteries composed of different micropillar sizes is studied in detail. The importance of controlling the width of micropillars is demonstrated and correlated with a simple theoretical model to optimize the battery properties. It is also shown that areal capacity values can be enhanced by improving the electrode/electrolyte interfaces using a simple treatment under vacuum.

Replicating the functionality of the human eye has been a challenge for more than a century, creating a great wealth of biomimetic and bioinspired devices, and providing ever improving models of the eye for myriad research purposes. As improvements in microelectronics have proceeded, individual components of the eye have been replicated, and models of the optical behaviour of the eye have improved. This review explores both work developed for improving medical components, with an ultimate aim of a fully functioning prosthetic eye, and work looking at improving existing devices through biomimetic means. It is hoped that this holistic approach to the subject will aid in the cross pollination of ideas between the two research foci. The review starts by summarising the reported measurements of optical parameters of various components of the eye. It then charts the development of individual bionic components. Particular focus is put on the development of bionic and biomimetic forms of the two main adaptive components of the eye, namely the lens and the iris, and the challenges faced in modelling the light sensitive retina. Work on each of these components is thoroughly reviewed, including an overview of the principles behind the many different approaches used to mimic the functionality, and discussion of the pros and cons of each approach. This is concluded by an overview of several reported models of the complete or semi-complete eye, including details of the components used and a summary of the models’ functionality. Finally, some consideration is given to the direction of travel of this field of research, and which existing approaches are likely to bring us closer to the long term goal of a fully functional analogue of the eye.