Kirigami-inspired, highly stretchable micro-supercapacitor patches fabricated by laser conversion and cutting.

The recent developments in material sciences and rational structural designs have advanced the field of compliant and deformable electronics systems. However, many of these systems are limited in either overall stretchability or areal coverage of functional components. Here, we design a construct inspired by Kirigami for highly deformable micro-supercapacitor patches with high areal coverages of electrode and electrolyte materials. These patches can be fabricated in simple and efficient steps by laser-assisted graphitic conversion and cutting. Because the Kirigami cuts significantly increase structural compliance, segments in the patches can buckle, rotate, bend and twist to accommodate large overall deformations with only a small strain (<3%) in active electrode areas. Electrochemical testing results have proved that electrical and electrochemical performances are preserved under large deformation, with less than 2% change in capacitance when the patch is elongated to 382.5% of its initial length. The high design flexibility can enable various types of electrical connections among an array of supercapacitors residing in one patch, by using different Kirigami designs

RF MEMS ohmic switches for matrix configurations

Two different topologies of radio frequency micro-electro-mechanical system (RF MEMS) series ohmic switches (cantilever and clamped–clamped beams) in coplanar waveguide (CPW) configuration have been characterized by means of DC, environmental, and RF measurements. In particular, on-wafer checks have been followed by RF test after vibration, thermal shocks, and temperature cycles. The devices have been manufactured on high resistivity silicon substrates, as building blocks to be implemented in different single-pole 4-throw (SP4 T), double-pole double-throw (DPDT) configurations, and then integrated in Low Temperature Co-fired Ceramics (LTCC) technology for the realization of large-order Clos 3D networks

Dynamic modelling for thermal micro-actuators using thermal networks.

International audienceThermal actuators are extensively used in microelectromechanical systems (MEMS). Heat transfer through and around these microstructures are very complex. Knowing and controlling them in order to improve the performance of the micro-actuator, is currently a great challenge. This paper deals with this topic and proposes a dynamic thermal modelling of thermal micro-actuators. Thermal problems may be modelled using electrical analogy. However, current equivalent electrical models (thermal networks) are generally obtained considering only heat transfers through the thickness of structures having considerable height and length in relation to width (walls). These models cannot be directly applied to micro-actuators. In fact, microactuator congurations are based on 3D beam structures, and heat transfers occur through and around length. New dynamic and static thermal networks are then proposed in this paper. The validities of both types of thermal networks have been studied. They are successfully validated by comparison with nite elements simulation and analytical calculations

Piezoelectric energy harvesting solutions

This paper reviews the state of the art in piezoelectric energy harvesting. It presents the basics of piezoelectricity and discusses materials choice. The work places emphasis on material operating modes and device configurations, from resonant to non-resonant devices and also to rotational solutions. The reviewed literature is compared based on power density and bandwidth. Lastly, the question of power conversion is addressed by reviewing various circuit solutions

Large-Stroke Dielectric Elastomer Actuators With Ion- Implanted Electrodes

In this paper, we present miniaturized polydimethyl- siloxane (PDMS)-based diaphragm dielectric elastomer actuators capable of out-of-plane displacement up to 25% of their diameter. This very large percentage displacement is made possible by the use of compliant electrodes fabricated by low-energy gold ion im- plantation. This technique forms nanometer-scale metallic clusters up to 50 nm below the PDMS surface, creating an electrode that can sustain up to 175% strain while remaining conductive yet having only a minimal impact on the elastomer’s mechanical properties. We present a vastly improved chip-scale process flow for fabricating suspended-membrane actuators with low- resistance contacts to implanted electrodes on both sides of the membrane. This process leads to a factor of two increase in breakdown voltage and to RC time constant shorter than mechanical time constants. For circular diaphragm actuator of 1.5–3-mm diameter, voltage- controlled static out-of-plane deflections of up to 25% of their diameter is observed, which is a factor of four higher than our previous published results. Dynamic characterization shows a mechanically limited behavior, with a resonance frequency near 1 kHz and a quality factor of 7.5 in air. Lifetime tests have shown no degradation after more than 4 million cycles at 1.5 kV. Conductive stretchable electrodes photolithographically defined on PDMS were demonstrated as a key step to further miniaturiza- tion, enabling large arrays of independent diaphragm actuators on a chip, for instance for tunable microlens arrays or arrays of micropumps and microvalves

Engineering for a changing world: 60th Ilmenau Scientific Colloquium, Technische Universität Ilmenau, September 04-08, 2023 : programme

In 2023, the Ilmenau Scientific Colloquium is once more organised by the Department of Mechanical Engineering. The title of this year’s conference “Engineering for a Changing World” refers to limited natural resources of our planet, to massive changes in cooperation between continents, countries, institutions and people – enabled by the increased implementation of information technology as the probably most dominant driver in many fields. The Colloquium, supplemented by workshops, is characterised but not limited to the following topics: – Precision engineering and measurement technology Nanofabrication – Industry 4.0 and digitalisation in mechanical engineering – Mechatronics, biomechatronics and mechanism technology – Systems engineering – Productive teaming - Human-machine collaboration in the production environment The topics are oriented on key strategic aspects of research and teaching in Mechanical Engineering at our university