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 […]
Category Archives: Sensors
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 […]
Researchers 3D print sensors for satellites
MIT News July 27, 2022 Researchers at MIT designed, fabricated and characterized digitally manufactured, compact retarding potential analyzers (RPAs) multi-electrode instruments that can be used as in-orbit mass spectrometers and as on-ground/in-orbit ion energy analyzers. The RPA electrode housing, which is the most critical component of the RPA, was additively manufactured in a printable glass-ceramic via vat polymerization, resulting in non-porous, high-temperature compatible, and high-vacuum compatible hardware. Four different RPA designs were synthesized to probe the ionosphere (design with floating grid alignment at the aperture level) and laboratory plasmas (designs with floating grid aperture alignment at the cluster level). Simulations […]
Hearing better with skin than ears
Science Daily July 1, 2022 Previously reported wearable sensors for smart human–machine interaction have limited sound-sensing quality as a consequence of a poor frequency response and a narrow acoustic-pressure range. Researchers in South Korea have developed a skin-attachable acoustic sensor that has higher sensing accuracy in wider auditory field than human ears, with flat frequency response (15–10 000 Hz) and a good range of linearity (29–134 dBSPL) as well as high conformality to flexible surfaces and human skin. They exploited the low residual stress and high processability of polymer materials in a diaphragm structure designed using acousto-mechano-electric modeling to achieve the […]
Laser writing may enable ‘electronic nose’ for multi-gas sensor
Science Daily June 30, 2022 Laser-induced thermal voxels (LITV) offer a facile platform to directly integrate nanocrystalline metal oxide and mixed metal oxide materials onto heating platforms, with access to a wide variety of compositions and morphologies including many transition metals and noble metals. Researchers at Pennsylvania State University combined laser writing and responsive sensor technologies to fabricate the first highly customizable microscale gas sensing devices. They investigated the sensing performance of a representative set of n-type and p-type LITV-deposited metal oxides and their mixtures (CuO, NiO, CuO/ZnO, and Fe2O3/Pt) in response to reducing and oxidizing gases (H2S, NO2, NH3, […]
Spray-n-Sense: Spray-painting sensors on any surface
Nanowerk June 27, 2022 An international team of researchers (Australia, Saudi Arabia) has demonstrated a sprayable on-site sensing tool, Spry-n-Sense, which consists of chromogen-doped polymer that is sprayed out in the form of nanofibers using a simple nebulization method. The nebulization method allows for nanofibers to be sprayed onto any surface. The sprayable nanofibers sensors only require compressed gas, making it possible to spray nanofibers even on non-conducting surfaces. The application performs on-site image analysis of the visually quantifiable color or fluorescence changes on the area of analyte exposure by calculating relative pixel intensity per ppm from photographs of the […]