Organic and Metallic Sensors on Complex 3-D Object Using an Original Method: Water Transfer Printing

International audienceSensors need to intimately wrap objects that we want to monitor, track, or supervise. By way of example, adding a strain gauge, some temperature or humidity sensors directly on 3-D objects, leads to improved structural health monitoring, protects materials from overheating, and sustaining a comfortable humidity level. In this letter, we present a conformal and substrate-free transfer of sensors to complex 3-D objects using water transfer printing (WTP) concept. Herein, the sensors are screen-printed using carbon and silver inks. To determine if the WTP process affects sensors performances, we compare the sensitivities obtained from transferred sensors with those directly screen-printed on polyethylene terephthalate (PET) substrate. Three types of sensors are studied to highlight WTP capabilities, paving the way for multisensor platforms. Obtained results highlight that transferred carbon strain gauges are more sensitive than screen-printed sensors. Therefore, their corresponding linear gauge factors were calculated as 18 and 15, respectively. Temperature sensitivity of carbon and silver-based sensors increases after WTP process. For silver temperature sensors, the corresponding sensitivities are 0.24%/°C for the screen-printed sensor and 0.28%/°C for the transferred one. Moreover, the WTP process demonstrated no significant impact on the transfer of carbon humidity sensor. © 2017 IEEE

Substrate-Free Transfer of Silicon- and Metallic-Based Strain Sensors on Textile and in Composite Material for Structural Health Monitoring

International audienceNew technologies to integrate electronics and sensors on or into objects can support the growth of embedded electronics. The method proposed in this paper has the huge advantage of being substrate-free and applicable to a wide range of target materials such as fiber-based composites, widely used in manufacturing, and for which monitoring applications such as fatigue, cracks, and deformation detection are crucial. Here, sensors are first fabricated on a donor substrate using standard microelectronic processes and then transferred to the host material by direct transfer printing. Results show the viability of composites instrumented by strain gauges. Indeed, dynamic and static measurements highlight that the deformations can be detected with high sensitivity both on the surface and at various points in the depth of the composite material. Thanks to this technology, for the first time, a substrate-free piezoresistive n-doped silicon strain sensor is transferred into a composite material and characterized as a function of strain applied on it. It is shown that the transfer process does not alter the electrical behavior of the sensors that are five times more sensitive than extensively used metallic ones. An application designed for monitoring the deformation of a rudder foil with a classic NACA profile in real time is presented

Flexible Microcrystalline Silicon Source-Gated Transistors with Negliglible DC Performace Degradation at 2.5 mm Bending Radius

International audienceThe first flexible source-gated transistors (SGTs) in microcrystalline silicon have been fabricated and characterized under bending stress. As SGTs are contact controlled devices, the channel does not modulate drain current, however its geometry has implications for operation. We show how reduced channel length in SGTs helps promote negligible threshold voltage shifts when strain is introduced with a radius of r = 2.5 mm

46 open clusters GaiaDR2 HR diagrams

VizieR online Data Catalogue associated with article published in journal Astronomy & Astrophysics with title 'Gaia Data Release 2: Observational Hertzsprung-Russell diagrams.' (bibcode: 2018A&A...616A..10G

Gaia DR2 sources in GC and dSph

VizieR online Data Catalogue associated with article published in journal Astronomy & Astrophysics with title 'Gaia Data Release 2. Kinematics of globular clusters and dwarf galaxies around the Milky Way' (bibcode: 2018A&A...616A..12G