Nanowerk March 6, 2023 Single quantum dots and coupled quantum dots formed with massless Dirac fermions can be viewed as artificial relativistic atoms and molecules, respectively. Such structures offer a unique testbed to study atomic and molecular physics in the ultrarelativistic regime. An international team of researchers (USA – UC Santa Cruz, UK, Japan) used a scanning tunnelling microscope to create and probe single and coupled electrostatically defined graphene quantum dots to unravel the magnetic-field responses of artificial relativistic nanostructures. When electrons in graphene are confined in a quantum dot, they travel in circular loops around the edge of the […]
Category Archives: Sensors
Electronic nose: Sensing the odor molecules on graphene surface layered with self-assembled peptides
Science Daily January 19, 2023 Researchers in Japan designed and developed three new peptides for graphene biosensors that can detect odor molecules to perform two main functions — acting as a biomolecular scaffold for self-assembly on a graphene surface and functioning as a bio-probe to bind the odor molecules. They showed that the peptides uniformly covered the graphene surface with the thickness of a single molecule. When representative odor molecules were injected into the functionalized graphene field-effect transistors (GFETs), graphene conductivity reduced indicating the binding of the odor molecules. The odor molecules gave rise to distinct signatures confirming that the […]
New nanowire sensors are the next step in the Internet of Things
Phys.og January 6, 2023 Despite intensive research and rapid progress in self-powered gas devices, most reported devices, specifically NO2 sensors for air pollution monitoring, have limited sensitivity, selectivity, and scalability. Researchers in Australia have demonstrated a photovoltaic self-powered NO2 sensor based on axial p–i–n homojunction InP nanowire (NW) arrays, that overcame these limitations. The device was designed by numerical simulation for insights into sensing mechanisms and performance enhancement. Without a power source, the InP NW sensor achieved an 84% sensing response to 1 ppm NO2 and recorded a limit of detection down to the sub-ppb level, with little dependence on […]
Flexible strain sensor enabled by carbon nanofibers can ‘read lips’
Phys.org November 29, 2022 While high sensitivity and wide working range are desired key parameters for a strain sensor, they are usually contrary to each other to be achieved on the same sensor due to the tight structure dependence of both. Researchers in China used an integrated membrane containing both parallel aligned and randomly aligned carbon nanofibers (CNFs) to design a flexible strain sensor with high sensitivity and wide strain detection range. The parallel aligned CNF membrane (p-CNF) exhibited a low strain detection limit and high sensitivity, while the random aligned CNF membrane (r-CNF) exhibits a large strain detection range. […]
Seeing concentrations of toxins with the naked eye
Phys.org November 3, 2022 Current detection methods can only respond to changes in a droplet’s bulk wetting properties, leading to poor detection limits. A team of researchers in the US (Harvard University, Ohio State University) has developed a design principle that overcomes this fundamental limitation by locally concentrating analytes within a droplet’s contact line to modulate the local surface roughness, which further affects droplet mobility. They designed surfaces enabled the ultrasensitive, naked-eye detection of amphiphiles through changes in the droplets’ sliding angles, even when the concentration is four to five orders of magnitude below their critical micelle concentration. They developed […]
Integration on a chip: Miniaturized infrared detectors
Phys.org October 25, 2022 In the infrared regime, there is a necessary compromise between high spectral bandwidth and high spectral resolution when miniaturizing dispersive elements, narrow band-pass filters, and reconstructive spectrometers. An international team of researchers (Switzerland, Spain, the Netherlands) demonstrated a proof-of-concept miniaturized Fourier-transform waveguide spectrometer that incorporates a subwavelength photodetector as a light sensor, consisting of colloidal mercury telluride quantum dot (Hg Te) and compatible with CMOS technology. The resulting spectrometer exhibited a large spectral bandwidth and moderate spectral resolution of 50 cm−1 at a total active spectrometer volume below 100 μm × 100 μm × 100 μm. According to the researchers this ultracompact spectrometer design […]
Organic thin-film sensors for light-source analysis and anti-counterfeiting applications
Science Daily September 6, 2022 Researchers in Germany have developed an organic thin-film sensor that describes a completely new way of identifying the wavelength of light and achieves a spectral resolution below one nanometer. The principle of operation of the new sensor is that light of unknown wavelength excites luminescent materials in a hair-thin film. The film consists of a mixture of phosphorescent and fluorescent entities, which absorb the light under investigation in different ways. The intensity of the afterglow can be used to infer the wavelength of the unknown input light. They exploited the fundamental physics of excited states […]
Silicon image sensor that computes
Science Daily August 26, 2022 To reduce the energy cost associated with transferring data between the sensing and computing units, in-sensor computing approaches are being developed where images are processed within the photodiode arrays. However, such methods require electrostatically doped photodiodes where photocurrents can be electrically modulated or programmed, and this is challenging in current CMOS image sensors that use chemically doped silicon photodiodes. An international team of researchers (USA – Harvard University, Brookhaven National Laboratory, South Korea) developed in-sensor computing using electrostatically doped silicon photodiodes by fabricating thousands of dual-gate silicon p–i–n photodiodes, which were integrated into CMOS image […]
Balloon fleet senses earthquakes from stratosphere
Phys.org July 28, 2022 Note: This article has been accepted for publication and undergone full peer review but has not been through the copyediting… The ground movements induced by seismic waves create acoustic waves propagating upward in the atmosphere, providing a practical solution to perform remote sensing of planetary interiors. However, a terrestrial demonstration of a seismic network based on balloon-carried pressure sensors has not been provided. Researchers in France reported the detection of a large, distant earthquake in a network of balloon-bound pressure sensors in the stratosphere. They demonstrated that quakes properties and planet internal structure can be probed […]
Researchers create biosensor by turning spider silk into optical fiber
Phys.org August 2, 2022 Researchers in Taiwan harvested dragline spider silk from the giant wood spider Nephila pilipes, which is native to Taiwan. They enveloped the silk, which is just 10 microns in diameter, with a biocompatible photocurable resin and cured it to form a smooth protective surface creating an optical fiber structure that was 100 microns in diameter, with the spider silk acting as the core and the resin as the cladding. They added a biocompatible nano-layer of gold to enhance the fiber’s sensing abilities. This process formed a thread-like structure with two ends. To use the fiber to […]