MIT researchers have developed the first molecular clock on a chip, which uses the constant, measurable rotation of molecules — when exposed to a certain frequency of electromagnetic radiation — to keep time. The chip could one day significantly improve the accuracy and performance of navigation on smartphones and other consumer devices.
Today’s most accurate time-keepers are atomic clocks. These clocks rely on the steady resonance of atoms, when exposed to a specific frequency, to measure exactly one second. Several such clocks are installed in all GPS satellites. By “trilaterating” time signals broadcast from these satellites — a technique like triangulation, that uses 3-D dimensional data for positioning — your smartphone and other ground receivers can pinpoint their own location.
In experiments, the molecular clock averaged an error under 1 microsecond per hour, comparable to miniature atomic clocks and 10,000 times more stable than the crystal-oscillator clocks in smartphones. Because the clock is fully electronic and doesn’t require bulky, power-hungry components used to insulate and excite the atoms, it is manufactured with the low-cost, complementary metal-oxide-semiconductor (CMOS) integrated circuit technology used to make all smartphone chips.
The chip-scale molecular clock can also be used for more efficient time-keeping in operations that require location precision but involve little to no GPS signal, such as underwater sensing or battlefield applications.
The researchers developed custom metal structures and other components that increase the efficacy of transistors, in order to shape a low-frequency input signal into a higher-frequency electromagnetic wave, while using as little power as possible. The chip consumes only 66 milliwatts of power. For comparison, common smartphone features — such as GPS, Wi-Fi, and LED lighting —can consume hundreds of milliwatts during use.
The chips could be used for underwater sensing, where GPS signals aren’t available. In those applications, sonic waves are shot into the ocean floor and return to a grid of underwater sensors. Inside each sensor, an attached atomic clock measures the signal delay to pinpoint the location of, say, oil under the ocean floor. The researchers’ chip could be a low-power and low-cost alternative to the atomic clocks.
Currently, the prototype needs some fine-tuning before it’s ready to reach consumer devices. The researchers currently have plans to shrink the clock even more and reduce the average power consumption to a few milliwatts, while cutting its error rate by another one or two orders of magnitude.
News Source: http://news.mit.edu/2018/molecular-clocks-improve-smartphone-navigation-performance-0713
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