Tiny sensor used in smart phones could create urban seismic network

Sep. 29, 2013 — A tiny chip used in smart phones to adjust the orientation of the screen could serve to create a real-time urban seismic network, easily increasing the amount of strong motion data collected during a large earthquake, according to a new study published in the October issue of the Bulletin of the Seismological Society of America (BSSA).

Micro-Electro-Mechanical System (MEMS) accelerometers measure the rate of acceleration of ground motion and vibration of cars, buildings and installations. In the 1990s MEMS accelerometers revolutionized the automotive airbag industry and are found in many devices used daily, including smart phones, video games and laptops.

Antonino D'Alessandro and Giuseppe D'Anna, both seismologists at Istituto Nazionale di Geosifica e Vulcanologia in Italy, tested whether inexpensive MEMS accelerometers could reliably and accurately detect ground motion caused by earthquakes. They tested the LIS331DLH MEMS accelerometer installed in the iPhone mobile phone, comparing it to the earthquake sensor EpiSensor ES-T force balance accelerometer produced by Kinemetrics Inc.

The tests suggest that the MEMS accelerometers can detect moderate to strong earthquakes (greater than magnitude 5) when located near the epicenter. The device produces sufficient noise to prevent it from accurately detecting lesser quakes -- a limitation to its use in monitoring strong motion.

D'Alessandro and D'Anna note that the technology is rapidly evolving, and there will soon be MEMS sensors that are sensitive to quakes less than magnitude 5. The real advantage, say the authors, is the widespread use of mobile phones and laptops that include MEMS technology, making it possible to dramatically increase coverage when strong earthquakes occur.

The current state of the MEMS sensors, suggest the authors, could be used for the creation of an urban seismic network that could transmit in real-time ground motion data to a central location for assessment. The rich volume of data could help first responders identify areas of greatest potential damage, allowing them to allocate resources more effectively.

The article, "Suitability of low-cost three-axis MEMS accelerometers in strong-motion seismology: tests on the LIS331DLH (iPhone) accelerometer," is published in October issue of BSSA.

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Paralysis promises smart silk technology

Sep. 19, 2013 — Oxford University researchers have harnessed the natural defence mechanism of silkworms, which causes paralysis, in what is a major step towards the large-scale production of silks with tailor-made properties.

Professor Fritz Vollrath and colleagues from the Oxford Silk Group at Oxford University's Department of Zoology collected silk directly from paralysed silkworms by injecting a chemical that is naturally produced by the animal. In the wild silkworms produce this hormone when they are injured since, as they move their bodies through hydrostatic pressure, without this self-induced paralysis their wounds would get worse and they would risk 'bleeding out'.

The team's report in the journal Biomacromolecules this week concludes that, in comparison to unparalysed silkworms, paralysis allows longer and more consistent silks to be collected by eliminating the ability of the silkworm to break and alter its silk fibre.

The direct 'forced reeling' of silk has been used in spiders for many years. However, reeling large amounts of silk directly from silkworms has not previously been possible. By tricking the silkworm into performing its natural response to injury and becoming paralysed the Oxford scientists show that it is possible to reel hundreds of meters of silk under full control.

Unlike unravelling cocoons, as in the silk textile industry, silkworm forced reeling allows the silk properties to be modified to suit particular purposes. This has important implications for the large-scale reeling of silkworms for industrial production of environmentally-friendly fibres for use in a range of applications -- from biomedical implants through to super-tough composite panels.

Silkworm paralysis may open the door to a range of silk technologies, using these animals which, unlike spiders, can be farmed at high-densities. Reeling of silk from paralysed worms is the subject of a recent patent, which also highlights the exciting potential for genetically modifying silkworms to induce paralysis 'on-demand', a particularly useful feature for mass-rearing.

'This is an interesting result as the paralysis prevents the silkworms breaking the fibre, but still allows silk spinning and collection,' said Beth Mortimer of the Oxford Silk Group, an author of the report.

'The commercial implications of this process are self evident: now we can make silks to order by manipulating the mechanical properties while at the same time adding functionality,' said Professor Vollrath.

Dr Alex Woods, an entomologist and Oxford-based medical researcher responsible for the original discovery said: 'importantly, this may allow us to make high-quality silks with a variety of desirable mechanical properties, in practical quantities, to finally expand this exceptionally well-suited biomaterial into key medical applications.'

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