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Polymeric semiconductors have been prepared whose molecular properties make them stretchable and healable — a milestone in the development of sophisticated organic electronic surfaces that mimic human skin. See Letter p.411 There is great interest and potential in the development of skin-inspired flexible and wearable electronic devices. Such devices require materials that twist, fold and bend with no loss in electronic—or material—properties. Zhenan Bao and colleagues report a conjugated polymer that also incorporates non-covalent interactions between adjacent chains, enabling the material to accommodate up to 100% strain whilst maintaining high charge-carrier mobility. In this proof-of-principle study the authors use the polymers to fabricate flexible and stretchable organic transistors that combine robustness with good electronic properties.

Electronic devices have advanced from their heavy, bulky origins to become smart, mobile appliances. Nevertheless, they remain rigid, which precludes their intimate integration into everyday life. Flexible, textile and stretchable electronics are emerging research areas and may yield mainstream technologies. Rollable and unbreakable backplanes with amorphous silicon field-effect transistors on steel substrates only 3 μm thick have been demonstrated. On polymer substrates, bending radii of 0.1 mm have been achieved in flexible electronic devices. Concurrently, the need for compliant electronics that can not only be flexed but also conform to three-dimensional shapes has emerged. Approaches include the transfer of ultrathin polyimide layers encapsulating silicon CMOS circuits onto pre-stretched elastomers, the use of conductive elastomers integrated with organic field-effect transistors (OFETs) on polyimide islands, and fabrication of OFETs and gold interconnects on elastic substrates to realize pressure, temperature and optical sensors. Here we present a platform that makes electronics both virtually unbreakable and imperceptible. Fabricated directly on ultrathin (1 μm) polymer foils, our electronic circuits are light (3 g m(-2)) and ultraflexible and conform to their ambient, dynamic environment. Organic transistors with an ultra-dense oxide gate dielectric a few nanometres thick formed at room temperature enable sophisticated large-area electronic foils with unprecedented mechanical and environmental stability: they withstand repeated bending to radii of 5 μm and less, can be crumpled like paper, accommodate stretching up to 230% on prestrained elastomers, and can be operated at high temperatures and in aqueous environments. Because manufacturing costs of organic electronics are potentially low, imperceptible electronic foils may be as common in the future as plastic wrap is today. Applications include matrix-addressed tactile sensor foils for health care and monitoring, thin-film heaters, temperature and infrared sensors, displays, and organic solar cells.

Biemann 1 calls into question our preliminary interpretations of our experimental results2. A comparison of laboratory and flight measurements should settle the uncertainties he raises. In addition to evaluating instrumental characteristics such as the 'piston effect', a technique we used for injecting oven-gas content for gas chromatography–mass spectrometry (GC–MS), such studies should enable a wide range of possible compositions for Titan's aerosols to be investigated. Our aerosol collection and pyrolysis (ACP) measurements in Titan's atmosphere can then be revisited.

ATS 2 satellite observations of enhanced radio noise bands in ionosphere and magnetosphere, noting plasma waves generation and coupling

Brief discussion of the concentration of helium ions in the upper atmosphere, emphasizing its dependence on temperature

ROTATION of the plane of polarization (the Faraday effect) of radio echoes from the Moon has been used by Browne, Evans, Hargreaves and Murray1 and by Evans2 to determine the total electron content of the ionosphere. The method is based upon the fact that the plane of polarization of a linearly polarized wave during its double passage through the ionosphere is rotated by an amount: where ƒ is the frequency of the transmitted wave in c./s., B is the Earth's magnetic field in gauss at ionospheric levels, θ is the angle between the direction of propagation and the Earth's field, δ is the zenith angle of the path, N is the electron density per cm.3 and dh is an element of height in cm. The limits of integration correspond to the region in which the ionization is large enough to make an appreciable contribution to the rotation. The assumption is made that B is constant throughout this region and has a value of 0.5 gauss. The value of the constant in the above equation published by Browne, et al. 1 appears to be in error by a factor of two, although the value given at a later date by Evans2 is correct. The reason for the error is that the angular rotation was taken to be equal to the phase difference between the ordinary and extraordinary rays. The parameter of interest, however, is the displacement from its initial position of the resultant of two vectors, one of which has rotated clockwise and one counter-clockwise. This resultant is displaced (ϕ1 − ϕ2)/2 from its initial position, where ϕ1 and ϕ2 are the absolute values of the rotations of the two component vectors.

Topside ionosphere of Venus and interaction with solar wind using Mariner 5 two frequency experiment

THE rate of fading of Earth satellite signals caused by the ionospheric Faraday effect was used by British workers1,2 to make estimates of the integrated electron content of the ionosphere up to the height of the satellite. The values obtained were, however, apparently too high. A possible reason for this is failure to take into account the radial velocity component of the satellite which, for certain portions of the orbit, can cause an appreciable contribution to the fading.