Prototype of Frame-Type Cantilever for Biosensor and Femtogram Detection

2010 ◽  
Vol 459 ◽  
pp. 134-139 ◽  
Author(s):  
Hayato Sone ◽  
Shoichi Ichikawa ◽  
Yuji Matsubara ◽  
Mitsumasa Suzuki ◽  
Haruki Okano ◽  
...  
Keyword(s):  
Gold Film ◽  
Fem Simulation ◽  
High Sensitivity ◽  
Film Deposition ◽  
Frequency Change ◽  
Mass Detection ◽  
Atomic Force ◽  
Highly Sensitive ◽  
Resonance Frequencies ◽  
Conventional Type

The possibility of realizing femtogram mass detection using a frame-type microcantilever has been studied in bioscience. To realize highly sensitive mass detection by reducing the viscose resistance in liquids, we designed frame-type cantilevers using finite element modeling (FEM). We fabricated prototypes of mesh-type, hole-type and conventional-type cantilevers using a semiconductor process. The properties of the cantilevers were measured by a conventional atomic force microscope (AFM) system. The measured resonance frequencies of the cantilevers were almost consistent with the calculated results of the FEM simulation in air. The resonance frequency and quality (Q) factor of the mesh-type cantilever were larger than those of the conventional-type cantilever in water. We measured the frequency change due to gold film deposition on the mesh-type cantilever. Then, we estimated the mass sensitivity of the cantilever at about 16.6 fg/Hz. This value is more than 10 times smaller than that of the conventional-type cantilever. These results indicate that the mesh-type cantilever has the advantage of reducing the viscous resistance and achieving high sensitivity in liquids.

scholarly journals High-sensitivity temperature sensor based on photonic crystal fiber fully coated with gold and PDMS films.

2021 ◽  
Author(s):  
yuhui feng ◽  
shuguang li ◽  
hongyu li ◽  
xiaojian meng ◽  
mengqiang li
Keyword(s):  
Photonic Crystal ◽  
Photonic Crystal Fiber ◽  
Temperature Sensor ◽  
Gold Film ◽  
Fem Simulation ◽  
Temperature Response ◽  
High Sensitivity ◽  
Temperature Sensitive ◽  
Pdms Layer ◽  
Crystal Fiber

Abstract This paper presented a high-sensitivity temperature sensor based on photonic crystal fiber fully coated with gold and PDMS films. For the convenience of production, gold film is coated outside the fiber cladding, and it is used to excite the surface plasmon resonance (SPR) effect. In addition, the temperature response has been effectively improved by depositing poly-dimethylsiloxane (PDMS) layer outside the gold film. This fully coated structure on the outside of PCF enables temperature-sensitive medium to be in direct contact with the environment, which reduces the difficulty of internal coating and filling. The influences of the parameters on the sensing characteristics are investigated by using the finite element method (FEM). Simulation results show that the average temperature sensitivity is up to 9.287 nm/℃ in the range of -20℃-40℃. Moreover, compared with other designs, the optimized process of structure in this study provides an effective method, which shows a wide application prospect to overcome the difficulty of filling liquid in the air holes.

Structural Approach to Improve the Response Characteristics of Copper Phthalocyanine Thin Film-Based NO2Gas Sensor

1997 ◽  
Vol 488 ◽  
Author(s):  
Tadashi Nagasawa ◽  
Kenji Murakami ◽  
Kenzo Watanabe
Keyword(s):  
Copper Phthalocyanine ◽  
Gas Sensing ◽  
High Sensitivity ◽  
Film Deposition ◽  
Gas Sensitivity ◽  
Vacuum Sublimation ◽  
Response Characteristics ◽  
Atomic Force ◽  
Film Microstructure ◽  
Sensing Characteristics

AbstractIn order to realize a high-sensitivity, low temperature operable NO2gas sensor, thin films of at-form copper phthalocyanine (α-CuPc) have been deposited by vacuum sublimation. In this study, we have attempted to improve the gas-sensing characteristics through a modification of the film microstructure. Firstly, the gas sensitivity is remarkably increased by an insertion of higher-sensitive layer (vanadyl Pc film) between the α-CuPc film and the glass substrate in the low gas concentration range. Secondly, a reversibility in cycles of gas doping and dedoping is improved by film deposition on hydrofluoric acid-treated substrate. It is found from atomic force microscope analyses that this phenomenon may be closely related to a modification of the film microstructure.

A NOVEL TECHNIQUE FOR MASS DETECTION OF A PIEZOELECTRIC CANTILEVER USING ACTIVE BIFURCATIONS

2010 ◽  
Vol 10 (03) ◽  
pp. 441-460 ◽  
Author(s):  
SHIH-HSUN YIN
Keyword(s):  
Complex Dynamics ◽  
High Sensitivity ◽  
Piezoelectric Sensor ◽  
Small Mass ◽  
Frequency Change ◽  
Nonlinear Feedback ◽  
Mass Detection ◽  
Novel Technique ◽  
Piezoelectric Cantilever ◽  
Bifurcation Behavior

Most current vibration-based chemical sensors and biosensors use the sensors resonance frequency change to quantify the small mass of chemical and biological agents attached to the surface of the sensors. In contrast, this paper proposes a novel technique for mass detection of a piezoelectric cantilever by actively triggering the bifurcation behavior. The cantilever is forced to bifurcate and exhibit complex dynamics (e.g., chaos) by using a nonlinear feedback excitation. Meanwhile, a feedback loop is constructed by measuring the voltage from a piezoelectric sensor, by processing the signal, and then by applying the voltage to a piezoelectric actuator. Due to the high sensitivity of a chaotic system to small parametric variations, the morphing of the attractor of the dynamic response of the piezoelectric cantilever can be utilized as an indicator to detect a small amount of mass and its location. The numerical investigation in this paper provides a basis to develop the next generation of high sensitivity vibration-based mass detection sensors.

High-sensitivity detection of gold labels by high-angle dark-field STEM imaging

1990 ◽  
Vol 48 (3) ◽  
pp. 892-893 ◽  
Author(s):  
Max T. Otten
Keyword(s):  
High Sensitivity ◽  
Dark Field ◽  
Bright Field ◽  
Backscattered Electron Imaging ◽  
Backscattered Electrons ◽  
Average Atomic Number ◽  
Highly Sensitive ◽  
Backscattered Electron ◽  
Electron Imaging ◽  
High Sensitivity Detection

Labelling of antibodies with small gold probes is a highly sensitive technique for detecting specific molecules in biological tissue. Larger gold probes are usually well visible in TEM or STEM Bright-Field images of unstained specimens. In stained specimens, however, the contrast of the stain is frequently the same as that of the gold labels, making it virtually impossible to identify the labels, especially when smaller gold labels are used to increase the sensitivity of the immunolabelling technique. TEM or STEM Dark-Field images fare no better (Figs. 1a and 2a), again because of the absence of a clear contrast difference between gold labels and stain.Potentially much more useful is backscattered-electron imaging, since this will show differences in average atomic number which are sufficiently large between the metallic gold and the stains normally used. However, for the thin specimens and at high accelerating voltages of the STEM, the yield of backscattered electrons is very small, resulting in a very weak signal. Consequently, the backscattered-electron signal is often too noisy for detecting small labels, even for large spot sizes.

scholarly journals Magnetoelastic Coupling and Delta-E Effect in Magnetoelectric Torsion Mode Resonators

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2022
Author(s):  
Benjamin Spetzler ◽  
Elizaveta V. Golubeva ◽  
Ron-Marco Friedrich ◽  
Sebastian Zabel ◽  
Christine Kirchhof ◽  
...  
Keyword(s):  
Low Frequency ◽  
High Sensitivity ◽  
Element Model ◽  
Mode Number ◽  
Frequency Change ◽  
General Description ◽  
Resonance Modes ◽  
Field Sensor ◽  
Magnetic Sensitivity ◽  
Bending Modes

Magnetoelectric resonators have been studied for the detection of small amplitude and low frequency magnetic fields via the delta-E effect, mainly in fundamental bending or bulk resonance modes. Here, we present an experimental and theoretical investigation of magnetoelectric thin-film cantilevers that can be operated in bending modes (BMs) and torsion modes (TMs) as a magnetic field sensor. A magnetoelastic macrospin model is combined with an electromechanical finite element model and a general description of the delta-E effect of all stiffness tensor components Cij is derived. Simulations confirm quantitatively that the delta-E effect of the C66 component has the promising potential of significantly increasing the magnetic sensitivity and the maximum normalized frequency change ∆fr. However, the electrical excitation of TMs remains challenging and is found to significantly diminish the gain in sensitivity. Experiments reveal the dependency of the sensitivity and ∆fr of TMs on the mode number, which differs fundamentally from BMs and is well explained by our model. Because the contribution of C11 to the TMs increases with the mode number, the first-order TM yields the highest magnetic sensitivity. Overall, general insights are gained for the design of high-sensitivity delta-E effect sensors, as well as for frequency tunable devices based on the delta-E effect.

scholarly journals Role of MRI evaluation in acute secondary inability to walk in children

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
K. H. Sedeek ◽  
K. Aboualfotouh ◽  
S. M. Hassanein ◽  
N. M. Osman ◽  
M. H. Shalaby
Keyword(s):  
Transverse Myelitis ◽  
High Sensitivity ◽  
Acute Disseminated Encephalomyelitis ◽  
Limb Weakness ◽  
Non Invasive ◽  
Highly Sensitive ◽  
Common Causes ◽  
Bilateral Lower Limb ◽  
Severity Of The Disease

Abstract Background Acute bilateral lower limb weakness is a common problem in children which necessitates a rapid method for diagnosis. MRI is a non-invasive imaging technique that produces high-quality images of the internal structure of the brain and spinal cord. Results MRI was very helpful in reaching rapid and prompt diagnosis in children with acute inability to walk. Acute disseminated encephalomyelitis (ADEM), Guillain–Barré syndrome (GBS), and acute transverse myelitis (ATM) were the most common causes in our study. MRI proved to be of high sensitivity in detecting the lesions and reaching the diagnosis in ADEM and GBS; however, there was no significant relation between the lesions’ size, enhancement pattern, and severity of the disease or prognosis, yet in ATM the site of the lesion and number of cord segment affection were significantly related to the severity of the disease and prognosis. Conclusion MRI is a quick tool to reach the diagnosis of children with acute secondary inability to walk, and to eliminate other differential diagnosis which is essential for proper treatment and rapid full recovery. It is highly sensitive in detecting the lesions, their site and size.

scholarly journals Highly sensitive detection of nitrobenzene by a series of fluorescent 2D zinc(ii) metal–organic frameworks with a flexible triangular ligand

RSC Advances ◽  
2021 ◽  
Vol 11 (39) ◽  
pp. 23975-23984
Author(s):  
Xue Yang ◽  
Yixia Ren ◽  
Hongmei Chai ◽  
Xiufang Hou ◽  
Zhixiang Wang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Metal Organic Frameworks ◽  
High Sensitivity ◽  
Fluorescent Sensors ◽  
Sensitive Detection ◽  
Donor Ligands ◽  
Highly Sensitive ◽  
Metal Organic ◽  
Highly Sensitive Detection

Four fluorescent 2D Zn-MOFs based on a flexible triangular ligand and linear N-donor ligands are hydrothermally prepared and used to detect nitrobenzene in aqueous solution with high sensitivity, demonstrating their potential as fluorescent sensors.

Rapid, highly sensitive and quantitative detection of interleukin 6 based on SERS magnetic immunoassay

2021 ◽  
Vol 13 (15) ◽  
pp. 1823-1831
Author(s):  
Xiaomei Wang ◽  
Li Ma ◽  
Shijiao Sun ◽  
Tingwei Liu ◽  
Hao Zhou ◽  
...  
Keyword(s):  
Interleukin 6 ◽  
High Sensitivity ◽  
Quantitative Detection ◽  
Detection Time ◽  
Highly Sensitive ◽  
Sandwich Method

We have developed a SERS magnetic immunoassay method based on the principle of sandwich method for rapid and quantitative detection of IL-6. The developed SERS method has the advantages of high sensitivity and detection time is only 15 min.

scholarly journals Nanoimprinted multifunctional nanoprobes for a homogeneous immunoassay in a top-down fabrication approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hubert Brueckl ◽  
Astrit Shoshi ◽  
Stefan Schrittwieser ◽  
Barbara Schmid ◽  
Pia Schneeweiss ◽  
...  
Keyword(s):  
Thin Film ◽  
Nanoimprint Lithography ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
In Vitro Diagnostics ◽  
Top Down ◽  
Highly Sensitive ◽  
Optical And Magnetic Properties ◽  
Lift Off

AbstractMultifunctional nanoparticles are discussed as versatile probes for homogeneous immunoassays for in-vitro diagnostics. Top-down fabrication allows to combine and tailor magnetic and plasmonic anisotropic properties. The combination of nanoimprint lithography, thin film deposition, and lift-off processing provides a top-down fabrication platform, which is both flexible and reliable. Here, we discuss the material compositions and geometrical designs of monodisperse multicomponent nanoparticles and their consequences on optical and magnetic properties. The rotational hydrodynamics of nanoparticles is measured and considered under the influence of magnetic shape anisotropy in the framework of the Stoner-Wohlfarth theory. The plasmon-optical properties are explained by discrete-dipole finite-element simulations. Rotational dynamical measurements of imprinted nanoprobes for two test proteins demonstrate the applicability as highly sensitive biomolecular nanoprobes.

scholarly journals Highly Sensitive Fluorescent Detection of Acetylcholine Based on the Enhanced Peroxidase-Like Activity of Histidine Coated Magnetic Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1207
Author(s):  
Hong Jae Cheon ◽  
Quynh Huong Nguyen ◽  
Moon Il Kim
Keyword(s):  
Magnetic Nanoparticles ◽  
High Sensitivity ◽  
High Specificity ◽  
Choline Oxidase ◽  
Fluorescent Detection ◽  
One Pot ◽  
Site Structure ◽  
Specificity And Sensitivity ◽  
Highly Sensitive ◽  
Peroxidase Mimics

Inspired by the active site structure of natural horseradish peroxidase having iron as a pivotal element with coordinated histidine residues, we have developed histidine coated magnetic nanoparticles (His@MNPs) with relatively uniform and small sizes (less than 10 nm) through one-pot heat treatment. In comparison to pristine MNPs and other amino acid coated MNPs, His@MNPs exhibited a considerably enhanced peroxidase-imitating activity, approaching 10-fold higher in catalytic reactions. With the high activity, His@MNPs then were exploited to detect the important neurotransmitter acetylcholine. By coupling choline oxidase and acetylcholine esterase with His@MNPs as peroxidase mimics, target choline and acetylcholine were successfully detected via fluorescent mode with high specificity and sensitivity with the limits of detection down to 200 and 100 nM, respectively. The diagnostic capability of the method is demonstrated by analyzing acetylcholine in human blood serum. This study thus demonstrates the potential of utilizing His@MNPs as peroxidase-mimicking nanozymes for detecting important biological and clinical targets with high sensitivity and reliability.

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