Phys.org November 16, 2021 Earthquakes, volcanic eruptions, and even severe weather events produce a medley of low-frequency infrasound waves below the range of human hearing. Infrasound waveforms generated by natural and anthropogenic phenomena contain important clues about the size and nature of the event. A team of researchers in the US (Sandia National Laboratory, Caltech) has shown that sensors on balloons in the lower stratosphere can record faithful representations of the near-source acoustic wave field at unprecedented range. The acoustic signature of a buried chemical explosion recorded at a range of 56 km and an altitude of 21.8 km was […]
Category Archives: Sensors
New theory for detecting light in the darkness of vacuum
Phys.org September 8, 2021 An accelerating photodetector is predicted to see photons in the electromagnetic vacuum. However, the extreme accelerations required have prevented the direct experimental verification of this quantum vacuum effect. Researchers at Dartmouth College considered many accelerating photodetectors that are contained within an electromagnetic cavity. They showed that the resulting photon production from the cavity vacuum can be collectively enhanced such as to be measurable. When the detector number exceeds a certain critical value, the vacuum photon production undergoes a phase transition from a normal phase to an enhanced super radiant-like, inverted lasing phase. Such a model may […]
Researchers use gold film to enhance quantum sensing with qubits in a 2D material
Phys.org September 3, 2021 The photoluminescence and the contrast of the optically detected magnetic resonance (ODMR) of hexagonal boron nitride (hBN) spin defects are relatively low so far, which limits their sensitivity. An international team of researchers (USA – Purdue University, Australia) used a gold film to increase the brightness of spin qubits by up to 17-fold. The gold film supports the surface plasmon that can speed up photon emission and hence more signals. They improved the contrast of their magnetic resonance signal by a factor of 10 by optimizing the design of a microwave waveguide substantially improving the sensitivity […]
Non-line-of-sight imaging with picosecond temporal resolution
Phys.org August 12, 2021 Non-line-of-sight (NLOS) imaging enables monitoring around corners and is promising for diverse applications. The resolution of transient NLOS imaging is limited to a centimeter scale, mainly by the temporal resolution of the detectors. Researchers in China have constructed an up-conversion single-photon detector with a high temporal resolution of ∼1.4 ps and a low noise count rate of 5 counts per second (cps). The detector operates at room temperature, near-infrared wavelength. They demonstrated high-resolution and low-noise NLOS imaging. The system can provide a 180 μm axial resolution and a 2 mm lateral resolution, which is more than […]
Single-step synthesis of solid-state sensors for detecting explosives
Nanowerk August 12, 2021 Most existing techniques to detect nitroaromatic compounds cannot be used in practical situations. Conventional methods available for the formulation of aggregation-induced emission (AIE) polymers are highly complicated, involving multi-step purification processes, proving detrimental in the application of AIE polymer-based probes. Researchers in South Korea have developed a single step protocol that produces tetraphenylethylene-hyperbranched polyglycidol (TPE-HPG) polymer solution that is added to water for formation of bright blue fluorescent TPE-HPG aggregated nanoparticles. Through empirical analysis, the researchers observed that the strong blue fluorescence of these nanoparticles is quenched by almost 95% on addition of 90 µM concentration […]
Using satellite data to warn people about volcanic eruptions
Phys.org June 21, 2021 Volcano monitoring of gas emissions provides insights into when explosions are likely to happen and unravel processes driving eruptions. An international team of researchers (UK, New Zealand) obtained data from the Sentinel-5 Precursor satellite, which had passed over Whakaari, New Zealand, shortly after it began erupting. By applying an algorithm to the data, they were able to reconstruct the events that had led to the volcano erupting. They found that SO2 flux and plume height data retrieved from TROPOMI satellite imagery before, during, and after the eruption showed that SO2 was detected without explosive activity on […]
Detecting mid-infrared light, one photon at a time
Phys.org June 2, 2021 An international team of researchers (USA – NIST, Jet Propulsion Laboratory, MIT, UK) has developed superconducting nanowire single-photon detectors based on tungsten silicide. To compensate for the lower energy carried by IR light they reduced the density of electrons in the wires that are available to absorb the photons. With fewer electrons available, the fraction of the total photon energy absorbed by any one electron is likely to be higher, increasing the likelihood that the electron would have enough energy to cross the superconducting gap and generate a signal when IR photons strike the detector. They […]
Slender robotic finger senses buried items
MIT News May 26, 2021 Technologies that sense the subterranean from above provide only a hazy view of submerged objects. Researchers at MIT have designed Digger Finger to meet the challenge of identifying buried objects. The Digger Finger is a slender cylinder with a beveled tip and uses a combination of blue LEDs and colored fluorescent paint. Its tactile sensing membrane is about 2 square centimeters. They ran its vibrating motor at different operating voltages, which changes the amplitude and frequency of the vibrations. They found that rapid vibrations helped “fluidize” the media, clearing jams and allowing for deeper burrowing. […]
Ultrafast, on-chip PCR could speed diagnosis during pandemics
Phys.org May 26, 2021 Researchers in South Korea have developed a plasmofluidic PCR chip comprising glass nanopillar arrays with Au nanoislands and gas-permeable microfluidic channels, which contain reaction microchamber arrays, a precharged vacuum cell, and a vapor barrier. The on-chip configuration allows both spontaneous sample loading and microbubble-free PCR reaction during which the plasmonic nanopillar arrays result in ultrafast photothermal cycling. After rapid sample loading, two-step PCR results for 40 cycles show rapid amplification in 264 s for lambda-DNA, and 306 s for plasmids expressing SARS-CoV-2 envelope protein. In addition, the in situ cyclic real-time quantification of amplicons clearly demonstrates […]
Nuclear terrorism could be intercepted by neutron-gamma detector that pinpoints source
EurekAlert May 19, 2021 Researchers in Sweden have developed a Neutron-Gamma Emission Tomography (NGET) system that goes beyond the capabilities of existing radiation portal monitors, by measuring the time and energy correlations between particles emitted in nuclear fission and using machine learning algorithms to visualize where they are coming from. The system looks for coincidences of neutron and gamma ray emissions–which when mapped together in real-time allow pinpointing their origin. They demonstrated the method on a radiation portal monitor prototype system based on fast organic scintillators measuring the characteristic fast time and energy correlations between particles emitted in nuclear fission […]