scholarly journals Cantilever-Based Sensor Utilizing a Diffractive Optical Element with High Sensitivity to Relative Humidity

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1673
Author(s):  
Catherine Grogan ◽  
Faolan Radford McGovern ◽  
Rory Staines ◽  
George Amarandei ◽  
Izabela Naydenova
Keyword(s):  
Relative Humidity ◽  
Diffraction Efficiency ◽  
Low Cost ◽  
Optical Element ◽  
High Sensitivity ◽  
Cantilever Deflection ◽  
Enhanced Sensitivity ◽  
Increased Sensitivity ◽  
Micro Cantilever ◽  
User Friendly

High-sensitivity and simple, low-cost readout are desirable features for sensors independent of the application area. Micro-cantilever sensors use the deflection induced by the analyte presence to achieve high-sensitivity but possess complex electronic readouts. Current holographic sensors probe the analyte presence by measuring changes in their optical properties, have a simpler low-cost readout, but their sensitivity can be further improved. Here, the two working principles were combined to obtain a new hybrid sensor with enhanced sensitivity. The diffractive element, a holographically patterned thin photopolymer layer, was placed on a polymer (polydimethylsiloxane) layer forming a bi-layer macro-cantilever. The different responses of the layers to analyte presence lead to cantilever deflection. The sensitivity and detection limits were evaluated by measuring the variation in cantilever deflection and diffraction efficiency with relative humidity. It was observed that the sensitivity is tunable by controlling the spatial frequency of the photopolymer gratings and the cantilever thickness. The sensor deflection was also visible to the naked eye, making it a simple, user-friendly device. The hybrid sensor diffraction efficiency response to the target analyte had an increased sensitivity (10-fold when compared with the cantilever or holographic modes operating independently), requiring a minimum upturn in the readout complexity.

scholarly journals Low-Cost and Scalable Platform with Multiplexed Microwell Array Biochip for Rapid Diagnosis of COVID-19

Research ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yang Wang ◽  
Kaiju Li ◽  
Gaolian Xu ◽  
Chuan Chen ◽  
Guiqin Song ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Reverse Transcriptase ◽  
Low Cost ◽  
High Sensitivity ◽  
High Specificity ◽  
Rapid Diagnosis ◽  
Negative Patient ◽  
Microwell Array ◽  
Custom Made ◽  
User Friendly

Sensitive detection of SARS-CoV-2 is of great importance for inhibiting the current pandemic of COVID-19. Here, we report a simple yet efficient platform integrating a portable and low-cost custom-made detector and a novel microwell array biochip for rapid and accurate detection of SARS-CoV-2. The instrument exhibits expedited amplification speed that enables colorimetric read-out within 25 minutes. A polymeric chip with a laser-engraved microwell array was developed to process the reaction between the primers and the respiratory swab RNA extracts, based on reverse transcriptase loop-mediated isothermal amplification (RT-LAMP). To achieve clinically acceptable performance, we synthesized a group of six primers to identify the conserved regions of the ORF1ab gene of SARS-CoV-2. Clinical trials were conducted with 87 PCR-positive and 43 PCR-negative patient samples. The platform demonstrated both high sensitivity (95.40%) and high specificity (95.35%), showing potentials for rapid and user-friendly diagnosis of COVID-19 among many other infectious pathogens.

High-quality RNA improves sensitivity of SARS-CoV-2 detection by colorimetric RT-LAMP

2021 ◽  
pp. 153537022110547
Author(s):  
Marta Puigmulé ◽  
Mònica Coll ◽  
Alexandra Pérez-Serra ◽  
Laura López ◽  
Ferran Picó ◽  
...  
Keyword(s):  
Diagnostic Test ◽  
Quantitative Pcr ◽  
Standard Method ◽  
Reverse Transcription ◽  
Gold Standard ◽  
High Sensitivity ◽  
High Quality ◽  
Gold Standard Method ◽  
Increased Sensitivity ◽  
User Friendly

The global SARS-CoV-2 pandemic requires a rapid, reliable, and user-friendly diagnostic test to help control the spread of the virus. Reverse transcription and quantitative PCR (RT-qPCR) is currently the gold standard method for SARS-CoV-2 detection. Here, we develop a protocol based on reverse transcription loop-mediated isothermal amplification (RT-LAMP) and demonstrate increased sensitivity of this technique using fresh RNA extracts compared to RNA samples subjected to freezing/thawing cycles. We further compare RT-LAMP to RT-qPCR and demonstrate that the RT-LAMP approach has high sensitivity in fresh RNA extracts and can detect positive samples with Ct values between 8 and 35.

Micro-structured fibers and their applications in fiber-optic sensors and random fiber lasers

2018 ◽  
Vol 96 (4) ◽  
pp. 359-365
Author(s):  
Yanping Xu ◽  
Xiaoyi Bao
Keyword(s):  
Fiber Lasers ◽  
Fiber Optic ◽  
Axial Strain ◽  
Low Cost ◽  
High Sensitivity ◽  
Dynamic Parameter ◽  
Fiber Optic Sensors ◽  
Spectral Correlation ◽  
Sensing Applications ◽  
Micro Cantilever

Micro-structured fibers are important devices that have drawn intensive attentions and proved to be powerful platforms for various applications over the past decades due to their remarkable merits and advantages, such as small footprint, immunity to electromagnetic interferences, light weight, high physical flexibility, and low cost. Modifications in optical fibers can be used as light-steering elements to excite and couple back different core and cladding modes and form various in-fiber structures, including in-line fiber interferometer, fiber micro-cantilever, fiber random gratings, and so on. These micro-structures, when applied as fiber-optic sensors in the presence of external disturbances, show high sensitivity in terms of the significant changes in the guided light features. Novel micro-structured bend-insensitive fiber-based in-line fiber interferometer and micro-cantilever have been proposed to realize both static and dynamic parameter measurements, including temperature, axial strain, surrounding refractive index, and vibration. We have also developed a novel fiber random grating along with a spectral correlation algorithm for simultaneous measurement of three static measurands. To move a step forward, random fiber lasers based on fiber random grating are achieved for either improving the laser performances or sensing applications of temperature, strain, and ultrasound measurements with high sensitivity.

scholarly journals CellProfiler: A fit tool for image analysis in droplet microfluidics

2019 ◽  
Author(s):  
Simona Bartkova ◽  
Marko Vendelin ◽  
Immanuel Sanka ◽  
Pille Pata ◽  
Ott Scheler
Keyword(s):  
Low Cost ◽  
High Sensitivity ◽  
Droplet Microfluidics ◽  
Biological Molecules ◽  
Analysis Tool ◽  
Microfluidic Assays ◽  
User Friendly ◽  
Free Open Source ◽  
Digital Quantification ◽  
High Throughput Manner

AbstractDroplet microfluidic assays are rapidly gaining popularity as the result of the ability to manipulate and monitor single biological molecules, individual cells or small populations of bacteria in pico- and nanoliter droplets, with high sensitivity, precision and accuracy in a high-throughput manner. Nonetheless, there is a demand for user-friendly and low-cost droplet analysis technology. In this article we meet this demand with free open-source software CellProfiler (CP). To illustrate the competence of CP as a droplet analysis tool, we show droplet digital quantification of viable fluorescent bacteria.

Micro Cantilever CO2 Gas Sensor Based on Mass

2015 ◽  
Vol 766-767 ◽  
pp. 528-533
Author(s):  
S. Subhashini ◽  
A. Vimala Juliet
Keyword(s):  
Residual Stresses ◽  
Resonant Frequency ◽  
Natural Frequency ◽  
Low Cost ◽  
High Sensitivity ◽  
The Other ◽  
Sensitive Coating ◽  
Metal Oxide Layer ◽  
Micro Cantilever

Sensors had gained importance in all fields of science and technology and development of real time small devices with high sensitivity for in situ measurements at low cost has gained momentum. Micromachined cantilever provides a solution to this hunt. MEMS cantilever are the simplest of all the other mechanical structures and hence is considered for the ease of fabrication. Here a chemical CO2 sensor is considered with the metal oxide layer as receptor to adsorb the CO2 molecules leading to an increase in mass and microcantilever as the transducer part converting the change in mass to change in natural frequency. The sensitive SnO2 layer increases the mass and hence decreases the resonant frequency. The inherent natural frequency of the cantilever is altered by the sensitive coating on top of the beam and the residual stresses present on the structure. In this paper, we investigate the SiO2 cantilever with SnO2 deposited on the top surface. Initially the microcantilever is analytically modelled and then is fabricated and characterized experimentally. Finally the error % is analysed between the analytical model and experimental results.

scholarly journals High-Sensitivity Whispering Gallery Mode Humidity Sensor Based on Glycerol Microdroplet Volumetric Expansion

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1746
Author(s):  
Pauls Kristaps Reinis ◽  
Lase Milgrave ◽  
Kristians Draguns ◽  
Inga Brice ◽  
Janis Alnis ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Free Space ◽  
Humidity Sensor ◽  
Low Cost ◽  
High Sensitivity ◽  
Whispering Gallery Mode ◽  
Whispering Gallery ◽  
Volumetric Expansion ◽  
Highly Sensitive ◽  
Good Repeatability

We demonstrate a highly sensitive whispering gallery mode (WGM) relative humidity (RH) sensor based on a glycerol microdroplet. WGMs were excited using a 760 nm tunable semiconductor laser. We used free space coupling, which is effective when using a liquid resonator. A detailed analysis of different parameters influencing the sensor’s characteristics (sensitivity, hysteresis, resolution, stability, and temperature) is presented. The sensitivity of the sensor is one of the highest reported (2.85 nm/% RH in the range 50–70% RH with the resolution 1 × 10−4% RH). This type of humidity sensor has several advantages, such as high sensitivity, extended lifetime, good repeatability, and low cost, as well as the use of a non-toxic and environmentally friendly liquid.

Compliant and Low-Cost Humidity Sensors Using Nano-Porous Polymer Membranes

2004 ◽  
Author(s):  
Bozhi Yang ◽  
Burak Aksak ◽  
Shan Liu ◽  
Qiao Lin ◽  
Metin Sitti
Keyword(s):  
Relative Humidity ◽  
Room Temperature ◽  
Capillary Condensation ◽  
Low Cost ◽  
Polymer Membranes ◽  
High Sensitivity ◽  
Porous Polymer ◽  
Humidity Sensors ◽  
Water Leakage Detection

This paper proposes non-fragile compliant humidity sensors that can be fabricated inexpensively on various types of nano-porous polymer membranes such as polycarbonate, cellulose acetate, and nylon membranes. The sensor contains a pair of interdigitated electrodes deposited on the nano-porous polymer membranes. The resistance and/or capacitance between these electrodes vary at different humidity levels with a very high sensitivity due to the water adsorption (capillary condensation) inside the nano-pores. The proposed sensors are low-cost in both material and fabrication. Due to its compliance, the sensors can be suitable for certain applications such as in-situ water leakage detection on roofs, where people can walk on top of them. Testing results demonstrated that the sensor changes resistance within large range of humidity values. For most sensors, the resistance changes from 0.1 GΩ to 2000 GΩ when the relative humidity changes from 39% to 100% at room temperature. It takes about 4–8 minutes for the resistance to reach steady state when the sensor was taken from 100% to 39% relative humidity at the room temperature.

EGFR-mutation detection in VTX-1-enriched CTCs, ctDNA, and comparison to tumor in patients with non-small cell lung cancer (NSCLC).

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e20525-e20525
Author(s):  
Jonathan Wade Goldman ◽  
Haiyan Liu ◽  
Meghah Vuppalapaty ◽  
Charles Wilkerson ◽  
Clementine Lemaire ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Kinase Inhibitors ◽  
Low Cost ◽  
Growth Factor Receptor ◽  
High Sensitivity ◽  
Circulating Tumor Dna ◽  
Egfr Mutations ◽  
Label Free ◽  
Enhanced Sensitivity ◽  
Nsclc Patients

e20525 Background: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI's) have shown dramatic clinical benefits when EGFR mutations are detected. These assays are mainly performed on tumor biopsies, which carry risks, are expensive and are not always successful. Moreover, secondary mutations, causing resistance to 1st & 2nd generation TKI’s develop during treatment and therefore mutations require ongoing monitoring. Circulating tumor cells (CTCs) or circulating tumor DNA (ctDNA) are promising for monitoring the patient over time and show enhanced sensitivity when combined1. The VTX-1 Liquid Biopsy System enables label-free capture of CTCs from blood and genomic assays downstream2. In this study, we demonstrate the sensitivity of a combined EGFR assay on VTX-1-enriched CTCs and ctDNA, using blood spiked with cancer cells & DNA and then with NSCLC patients. Methods: NSCLC cells (A549: wt, H1975: L858R+ & T790M+, HCC827: 19del+) were used to validate the assay. H1975 cells and HCC827 DNA were spiked in blood. Plasma was extracted and the plasma depleted blood was processed through VTX-1. The collected plasma and enriched cells were subjected to the detection of 19del, L858R and T790M EGFR mutations using the EntroGen ctEGFR kit. Later, blood and tumor were collected from NSCLC patients and analyzed for EGFR mutations on biopsies, ctDNA and CTCs. Results: Mutant DNA was detected for an input as low as 0.5 ng (~83 cells), with a sensitivity from 0.1% to 2% for a total DNA of 25ng (~4 cancer cells & 4000 WBCs) to 1ng (~4 cancer cells & 200 WBCs). Processing of plasma-depleted-blood with Vortex showed the same efficiency compared to whole blood. Mutations were detected from enriched cells and plasma respectively for 100 H1975 cells and 0.5ng of HCC827 DNA spiked in 2mL blood. NSCLC patients are being enrolled and results will be presented at the conference. Conclusions: The ctEGFR assay performed well on VTX-1 enriched cells and ctDNA, enabling a low cost approach to analyze EGFR mutations from a single blood tube with high sensitivity, potentially being a useful tool for guiding treatment of NSCLC patients. 1.Sundaresan, et al. Clin Cancer Res 2016. 2. Kidess-Sigal, et al. Oncotarget 2016.

Tools of Transformation: Appropriate Technology in U.S. Countercultural Literature

2012 ◽  
Vol 44 (2) ◽  
pp. 75-93
Author(s):  
Peter Mortensen
Keyword(s):  
Low Cost ◽  
Appropriate Technology ◽  
Small Scale ◽  
Environmental Transformation ◽  
Buckminster Fuller ◽  
1960S And 1970S ◽  
The 1960S ◽  
Environmentally Sound ◽  
User Friendly ◽  
Second Wave

This essay takes its cue from second-wave ecocriticism and from recent scholarly interest in the “appropriate technology” movement that evolved during the 1960s and 1970s in California and elsewhere. “Appropriate technology” (or AT) refers to a loosely-knit group of writers, engineers and designers active in the years around 1970, and more generally to the counterculture’s promotion, development and application of technologies that were small-scale, low-cost, user-friendly, human-empowering and environmentally sound. Focusing on two roughly contemporary but now largely forgotten American texts Sidney Goldfarb’s lyric poem “Solar-Heated-Rhombic-Dodecahedron” (1969) and Gurney Norman’s novel Divine Right’s Trip (1971)—I consider how “hip” literary writers contributed to eco-technological discourse and argue for the 1960s counterculture’s relevance to present-day ecological concerns. Goldfarb’s and Norman’s texts interest me because they conceptualize iconic 1960s technologies—especially the Buckminster Fuller-inspired geodesic dome and the Volkswagen van—not as inherently alienating machines but as tools of profound individual, social and environmental transformation. Synthesizing antimodernist back-to-nature desires with modernist enthusiasm for (certain kinds of) machinery, these texts adumbrate a humanity- and modernity-centered post-wilderness model of environmentalism that resonates with the dilemmas that we face in our increasingly resource-impoverished, rapidly warming and densely populated world.

scholarly journals Pocket MUSE: an affordable, versatile and high-performance fluorescence microscope using a smartphone

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yehe Liu ◽  
Andrew M. Rollins ◽  
Richard M. Levenson ◽  
Farzad Fereidouni ◽  
Michael W. Jenkins
Keyword(s):  
High Performance ◽  
Point Of Care ◽  
Low Cost ◽  
Consumer Electronics ◽  
Practical Implementation ◽  
The Novel ◽  
Point Of Care Diagnostics ◽  
Optical Module ◽  
Optical Configuration ◽  
User Friendly

AbstractSmartphone microscopes can be useful tools for a broad range of imaging applications. This manuscript demonstrates the first practical implementation of Microscopy with Ultraviolet Surface Excitation (MUSE) in a compact smartphone microscope called Pocket MUSE, resulting in a remarkably effective design. Fabricated with parts from consumer electronics that are readily available at low cost, the small optical module attaches directly over the rear lens in a smartphone. It enables high-quality multichannel fluorescence microscopy with submicron resolution over a 10× equivalent field of view. In addition to the novel optical configuration, Pocket MUSE is compatible with a series of simple, portable, and user-friendly sample preparation strategies that can be directly implemented for various microscopy applications for point-of-care diagnostics, at-home health monitoring, plant biology, STEM education, environmental studies, etc.

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