Lucus Planum, extending for a radius of approximately 500 km around 181°E, 5°S, is part of the Medusae Fossae Formation (MFF), a set of several discontinuous deposits of fine‐grained, friable material straddling across the Martian highland‐lowland boundary. The MFF has been variously hypothesized to consist of pyroclastic flows, pyroclastic airfall, paleopolar deposits, or atmospherically deposited icy dust driven by climate cycles. Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS), a low‐frequency subsurface‐sounding radar carried by European Space Agency's Mars Express, acquired 238 radar swaths across Lucus Planum, providing sufficient coverage for the study of its internal structure and dielectric properties. Subsurface reflections were found only in three areas, marked by a distinctive surface morphology, while the central part of Lucus Planum appears to be made of radar‐attenuating material preventing the detection of basal echoes. The bulk dielectric properties of these areas were estimated and compared with those of volcanic rocks and ice‐dust mixtures. Previous interpretations that east Lucus Planum and the deposits on the northwestern flanks of Apollinaris Patera consist of high‐porosity pyroclastic material are strongly supported by the new results. The northwestern part of Lucus Planum is likely to be much less porous, although interpretations about the nature of the subsurface materials are not conclusive. The exact origin of the deposits cannot be constrained by radar data alone, but our results for east Lucus Planum are consistent with an overall pyroclastic origin, likely linked to Tharsis Hesperian and Amazonian activity.
Soft and stretchable electronic materials have a number of unique applications, not least within sensors for monitoring human health. Through development of appropriate inks, micro‐extrusion 3D printing offers an appealing route for integrating soft electronic materials within wearable garments. Toward this objective, here a series of conductive inks based on soft thermoplastic styrene–ethylene–butylene–styrene elastomers combined with silver micro‐flakes, carbon black nanoparticles, or poly(3,4‐ethylenedioxythiophene) (PEDOT) conducting polymer additives, is developed. Their electrical and mechanical properties are systematically compared and found to be highly dependent on additive amount and type. Thus, while silver composites offer the highest conductivity, their stretchability is far inferior to carbon black composites, which can maintain conductivity beyond 400% strain. The PEDOT composites are the least conductive and stretchable but display unique properties due to their propensity for ionic conductivity. To integrate these inks, as well as insulating counterparts, into functional designs, a multi‐material micro‐extrusion 3D printing routine for direct deposition onto stretchable, elastic fabrics is established. As demonstration, prototypes are produced for sensing common health markers including strain, physiological temperatures, and electrocardiograms. Collectively, this work demonstrates multi‐material 3D printing of soft styrene–ethylene–butylene–styrene elastomer composites as a versatile method for fabricating soft bio‐sensors.
Nanostructuration is a promising tool for enhancing the performance of sensors based on electrochemical transduction. Nanostructured materials allow increasing the surface area of the electrode, and to improve the limit...
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