Coating inkjet-printed traces of silver nanoparticle (AgNP) ink with a thin layer of eutectic gallium indium (EGaIn) increases the electrical conductivity by six-orders of magnitude and significantly improves tolerance to tensile strain. This enhancement is achieved through a room-temperature "sintering" process in which the liquid-phase EGaIn alloy binds the AgNP particles (≈100 nm diameter) to form a continuous conductive trace. Ultrathin and hydrographically transferrable electronics are produced by printing traces with a composition of AgNP-Ga-In on a 5 µm-thick temporary tattoo paper. The printed circuit is flexible enough to remain functional when deformed and can support strains above 80% with modest electromechanical coupling (gauge factor ≈1). These mechanically robust thin-film circuits are well suited for transfer to highly curved and nondevelopable 3D surfaces as well as skin and other soft deformable substrates. In contrast to other stretchable tattoo-like electronics, the low-cost processing steps introduced here eliminate the need for cleanroom fabrication and instead requires only a commercial desktop printer. Most significantly, it enables functionalities like "electronic tattoos" and 3D hydrographic transfer that have not been previously reported with EGaIn or EGaIn-based biphasic electronics.

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It is well known that insects and other animals use olfactory senses in a wide variety of behavioural processes, namely to recognize and locate food sources, detect predators, and find mates. This article discusses the gathering of olfactive information and its utilization by a mobile robot to find a specific odour source in a room with turbulent phenomena's and multiple sources of odour. Three navigation algorithms are compared with a simple gas sensor and with an electronic nose. Their performance in finding an ethanol source in a room with obstacles is evaluated. The first navigation strategy is based on bacteria chemotaxis. The second strategy is based on the male silkworm moth algorithm that is used to search and track a female moth pheromone plume. The last strategy is based on the estimation of odour geometry and gradient tracking. The electronic nose utilized is composed by an array of different and weakly selective metal oxide gas sensors. The odours are identified and quantified by a pattern recognition algorithm based on an artificial neural network. The test bed for the navigation algorithms was a Nomad Super Scout II mobile robot. ᮊ

A bi-phasic ternary Ag–In–Ga ink that demonstrates high electrical conductivity, extreme stretchability, and low electromechanical gauge factor (GF) is introduced. Unlike popular liquid metal alloys such as eutectic gallium–indium (EGaIn), this ink is easily printable and nonsmearing and bonds strongly to a variety of substrates. Using this ink and a simple extrusion printer, the ability to perform direct writing of ultrathin, multi-layer circuits that are highly stretchable (max. strain >600%), have excellent conductivity (7.02 × 105 S m–1), and exhibit only a modest GF (0.9) related to the ratio of percent increase in trace resistance with mechanical strain is demonstrated. The ink is synthesized by mixing optimized quantities of EGaIn, Ag microflakes, and styrene-isoprene block copolymers, which functions as a hyperelastic binder. When compared to the same composite without EGaIn, the Ag–In–Ga ink shows over 1 order of magnitude larger conductivity, up to ∼27× lower GF, and ∼5× greater maximum stretchability. No significant change over the resistance of the ink was observed after 1000 strain cycles. Microscopic analysis shows that mixing EGaIn and Ag microflakes promotes the formation of AgIn2 microparticles, resulting in a cohesive bi-phasic ink. The ink can be sintered at room temperature, making it compatible with many heat-sensitive substrates. Additionally, utilizing a simple commercial extrusion based printer, the ability to perform stencil-free, digital printing of multi-layer stretchable circuits over various substrates, including medical wound-dressing adhesives, is demonstrated for the first time.

Although significant improvements in energy efficiency have been achieved in home appliances and lighting, the electricity consumption in the European Union household has increased by 2% per year during the past 10 years. Some reasons are associated with an increased degree of basic comfort and level of amenities and with the widespread utilization of new types of loads. Wishing to increase the understanding of the energy consumption in the EU households for the different types of equipment including the consumers' behaviour and comfort levels, and to identify demand trends, an energy monitoring campaign, was carried out in 12 geographically representative EU countries, accompanied by a lifestyle survey. From the measurements carried out it was concluded that Information Technologies and entertainment loads are key contributors to the power demand. In basically all types of loads there is wide range of performance levels in the models available in the market. Available technology, associated with responsible consumer behaviour, can reduce wasteful consumption. Based on a bottom up approach the European residential sector potential electricity savings that can be implemented by existing technologies and improved behaviour can reach 48%. The paper presents policy recommendations promoting market transformation and behavioural changes in the equipment selection and operation.

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We introduce a soft ultrathin and stretchable electronic skin with surface-mounted components that can be transferred and wrapped around any three-dimensional (3D) surface or self-adhere to the human skin. The ∼5 μm thick circuit is fabricated by printing the pattern over a temporary tattoo paper using a desktop laser printer, which is then coated with a silver ink and eutectic gallium–indium (EGaIn) liquid metal alloy. The resulting “Ag–In–Ga” traces are highly conductive and maintain low electrical resistivity as the circuit is stretched to conform to nondevelopable 3D surfaces. We also address integration of surface-mounted microelectronic chips by introducing a novel z-axis conductive interface composed of magnetically aligned EGaIn-coated Ag–Ni microparticles embedded in polyvinyl alcohol (PVA). This “zPVA conductive glue” allows for robust electrical contacts with microchips that have pins with dimensions as small as 300 μm. If printed on the temporary tattoo transfer paper, the populated circuit can be attached to a 3D surface using hydrographic transfer. Both printing and interfacing processes can be performed at the room temperature. We demonstrate examples of applications, including an electronic tattoo over the human epidermis for electromyography signal acquisition, an interactive circuit with touch buttons, and light-emitting diodes transferred over the 3D printed shell of a robotic prosthetic hand, and a proximity measurement skin transferred over a 3D surface.