Phys.org January 12, 2022 Researchers in the Netherlands developed and demonstrated a different approach to spectral sensing which dramatically simplifies the requirements on the hardware and allows the monolithic integration of the sensors. They used an array of resonant-cavity-enhanced photodetectors, each featuring a distinct spectral response in the 850-1700 nm wavelength range. They showed that prediction models can be built directly using the responses of the photodetectors, despite the presence of multiple broad peaks, releasing the need for spectral reconstruction. They used the sensor to measure the nutritional properties of many materials including milk and to classify different types of plastic. […]
Category Archives: Sensors
Novel biosensors set to revolutionize brain-controlled robotics
Science Daily December 22, 2021 Researchers in Australia have detected the EEG signals with high sensitivity using epitaxial graphene (EG) grown on silicon carbide on silicon. The dry and non-invasive approach exhibited a markedly improved skin contact impedance when benchmarked to commercial dry electrodes, as well as superior robustness, allowing prolonged and repeated use also in a highly saline environment. They observed a new phenomenon of surface conditioning of the EG electrodes. The prolonged contact of the EG with the skin electrolytes functionalize the grain boundaries of the graphene, leading to the formation of a thin surface film of water […]
Color-changing magnifying glass gives clear view of infrared light
Phys.org December 2, 2021 An international team of researchers (UK, Belgium, Spain) used a single layer of molecules to absorb the mid-infrared light inside their vibrating chemical bonds. These shaking molecules donate their energy to visible light that they encounter, ‘upconverting’ it to emissions closer to the blue end of the spectrum, which can then be detected by visible-light cameras. The challenge was to make sure the quaking molecules met the visible light quickly enough. They devised a way to sandwich single molecular layers between a mirror and tiny chunks of gold to twist and squeeze light. The researchers emphasize […]
Machine learning refines earthquake detection capabilities
Science Daily November 1, 2021 New satellites are opening a new window into tectonic processes by allowing researchers to observe length and time scales that were not possible in the past. However, existing algorithms are not suited for the vast amount of InSAR data flowing in from these new satellites. To process all this data an international team of researchers (USA – Los Alamos National Laboratory, France) developed the first tool based on machine learning algorithms to extract ground deformation from InSAR data, which enables the detection of ground deformation automatically — without human intervention — at a global scale, […]
Stratospheric balloons listen in on ground activity
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 […]
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 […]