Resonance Sensor System Research Articles

Proposal of compact LSPR sensor system by filter-free wavelength sensor

A compact localized surface plasmon resonance (LSPR) sensor system integrated with a filter-free wavelength sensor (FFS) for quantitative virus detection methods was demonstrated. The changed transmission spectrum of the LSPR sensor by molecule was measured using an FFS as a transducer without a conventional spectrometer. We designed and fabricated gold nanostructures optimized for virus detection. As the concentration of S-protein RBD changed from 0.1 to 10 ng ml−1, the change in the current ratio from 0.012 to 0.094 was obtained by the FFS. We expect a compact and rapid virus detection system with qualitatively diagnose to be realized using the proposed method.

Prevention of Ventilator Associated Pneumonia by Gastric Residual Estimation Using Highly Coupled Resonant Enteric Tube Sensor System

Prevention of Ventilator Associated Pneumonia by Gastric Residual Estimation Using Highly Coupled Resonant Enteric Tube Sensor System

Implementation and calibration of a phase detector circuit as a QCM sensor to characterize fluid properties

In this work, a quartz resonator or QCM sensor system based on a phase detector circuit is implemented. Until now, the phase detection method in QCM sensors has been used for mass measurement applications. In this work, the system is characterized for its use in applications to measure the properties of a liquid (density and viscosity). In a first part, the implementation of the system is described. Once implemented, it is calibrated with solutions of increasing viscosities, obtaining the sensitivity equation and the resolution of the output voltage to changes over the square root of the density-viscosity product. Finally, the results are compared with those obtained by the authors in previous works using oscillator circuits and a network analyzer as electronic measurement interfaces.

Modeling of a cylindrical resonant photoacoustic cell for high sensitive gas detection

AbstractPhotoacoustic spectroscopy (PAS) is a sensitive spectroscopic technique for trace gas sensing. As a key component of a PA sensor system, the cell constant of the cylindrical PA cell has been simulated for optimizing geometric design, and the acoustic pressure distribution and frequency response of the first longitudinal and radial modes are analyzed by using a self‐established algorithm model. According to the theoretical simulation, a resonant PAS sensor system was finally designed and evaluated at the first longitudinal mode for trace water vapor detection. Highly sensitive wavelength modulation spectroscopy and second harmonic detection technique was combined with PAS detection method for enhancing sensitivity. Allan deviation analysis indicates that a detection limit of 2 ppm for H2O could be achieved at an optimal integration time of 200 s, corresponding to a normalized noise equivalent absorption coefficient of .

Wireless differential resonance frequency pressure sensor: Circuital model and prototype validation

This article presents a pressure sensor composed of a set of three Archimedean spiral inductors. One of them is below the other two concentric spirals, where the upper coils are over a flexible membrane. When external pressure is applied over the sensor, the membrane deforms and changes the distance between the lower spirals and the upper inside coil, the capacitance, and its resonance frequency. However, once the sensor is in contact with a conductive medium, a change in the effective permittivity surrounding the sensor takes place reshaping the resonant frequencies. To improve the sensor response, we introduce a reader resonator sensor system. We present the comparative response of the system as a prototype, an analytical model, and a finite element model (FEM). The prototype system is fabricated using a photolithographic process for the elements of the sensor over a polymethylsiloxane and glass substrate, while the reader is fabricated over a FR4 substrate. COMSOL Multiphysics is used for the FEM simulation of the system to evaluate its behavior. The analytical model involves the integration of techniques to obtain the effective permittivity for each element plane and a coupled magnetic resonance to represent the interaction of the parts. We obtain a correspondence between the resonances of the different elements, with a maximum displacement frequency of 240 MHz for the proposed model, and 80 MHz in the FEM case related to the implemented prototype. The accuracy of this model allows a fast analysis to improve the design of this type of topology without high computational processing.

Optical fiber plasmonic sensor for the ultrasensitive detection of copper (II) ion based on trimetallic Au@AgPt core-shell nanospheres

This article presents for the first time an ultrasensitive localized surface plasmon resonance (LSPR) sensor system based on multimode-singlemode-multimode fiber (MMF-SMF-MMF) structure for the accurate measurement of copper (II) Ion (Cu2+). Citrate-stabilized Au@AgPt core-shell nanospheres (NSs) with a rough AgPt alloy outer shell were synthesized in house, and then adhered onto the sensing section of MMF-SMF-MMF structure through silane coupling agent. Finally, the Au@AgPt NSs-coated optical fiber probe surface was covered with a layer of PEI as the chelating agent for specific Cu2+ trapping. The detection process of Cu2+ is conducted by monitoring the resonance intensity variation of the transmission spectrum, which is due to the local refractive index changes result- ing from the specific interactions between Cu2+ in solution and PEI immobilized on the sensor surface. The proposed PEI-Au@AgPt NSs modified fiber sensor achieved an ultralow Cu2+ detection level down to 10−16 mol/L. The facile fabrication, pollution-free, high sensitivity and cost-effectiveness of the optical fiber sensor system make it rather promising for the precise Cu2+ monitoring in a wide range of biological application scenarios.

Fiber Optic Particle Plasmon Resonance-Based Immunoassay Using a Novel Multi-Microchannel Biochip.

A novel multi-microchannel biochip fiber-optic particle plasmon resonance (FOPPR) sensor system for the simultaneous detection of multiple samples. The system integrates a novel photoelectric system, a lock-in module, and an all-in-one platform incorporating optical design and mechanical design together to improve system stability and the sensitivity of the FOPPR sensor. The multi-microchannel FOPPR biochip has been developed by constructing a multi-microchannel flow-cell composed of plastic material to monitor and analyze five samples simultaneously. The sensor system requires only 30 μL of sample for detection in each microchannel. Moreover, the total size of the multi-microchannel FOPPR sensor chip is merely 40 mm × 30 mm × 4 mm; thus, it is very compact and cost-effective. The analysis was based on calibration curves obtained from real-time sensor response data after injection of sucrose solution, streptavidin and anti-dinitrophenyl (anti-DNP) antibody of known concentrations over the chips. The results show that the multi-microchannel FOPPR sensor system not only has good reproducibility (coefficient of variation (CV) < 10%), but also excellent refractive index resolution (6.23 ± 0.10 × 10−6 refractive index unit (RIU)). The detection limits are 2.92 ± 0.28 × 10−8 g/mL (0.53 ± 0.01 nM) and 7.48 ± 0.40 × 10−8 g/mL (0.34 ± 0.002 nM) for streptavidin and anti-DNP antibody, respectively.

Refractive Index Monitoring Technique Using a Smartphone Based on the Metal Nanoshell Array Sensing Method

A novel surface plasmon resonance (SPR) sensor system using a smartphone based on the metal nanoshell array sensing method is proposed and developed. The micro-flow injection method was used to prepare two-dimensional colloidal microsphere template, the metal nanoshell array was fabricated by combining the microsphere template and the magnetron sputtering technology. A smartphone and a diffraction grating are employed as interrogation system, in which a fiber with a 45° polished tip connect the flashlight and the camera on the smartphone. The diffraction grating spreads the transmission spectrum over the camera's pixels to allow for repeatable measurements of wavelength shifts of the sensor. The reflection intensity of sensor can be measured by smartphone and the surrounding refractive index is monitored by the shift of the reflection spectrum. The experimental results show that the sensitivity of the SPR refractive index sensor based on the metal nanoshell array is about 927 nm/RIU for a refractive index (RI) range from 1.352 to 1.363, and the quality factor of that is about 18.5. The results show that this technique can provide a low-cost, portable and intelligent diagnostic platform for the measurement of the SPR refractive index sensor.

A Partial-Dip Observation Mechanism for the Resolution Improvement of Spectrum-Like Surface Plasmon Resonance Waveforms

Continuum of signals exhibiting spectral features, such as asymmetric waveforms and peaks, are common in optoelectric measurements. In ordinary circumstances, the peaks of spectrum-like waveforms carry critical information, and accurately identifying peak location is of great significance. However, due to the finite hardware resources of practical electrical instruments, the accuracy of peak identifying is usually limited. To improve the resolution performance without hardware upgrading, we propose a weighted centroid algorithm in this paper. Based on a representative experimental verification of surface plasmon resonance sensor system under angular-interrogation, we propose that the peak-locating performance is primarily determined by the dramatically changing part, rather than the entire waveform. By manually cutting out the partial waveform with drastic change ratio via an appropriate gain amplification, the accuracy of spectrum-like signal locating is capable to be enhanced, and the sensor resolution performance, nearly one order of magnitude.

Moisture Monitoring in Fluid-Bed Granulation by Multi-Resonance Microwave Sensor: Applicability on Crystal-Water Containing Donepezil Granules.

Multi-resonance microwave sensors have recently been introduced for moisture monitoring of pharmaceutical particulates up to > 20% residual moisture. The extended measuring range compared to previous systems as well as the microwave moisture values independent of other physical attributes make them promising process analytical technology (PAT) tools for various pharmaceutical production processes. However, so far, research focused on measurements on raw materials or drug-free model granulates and has neither evaluated the applicability for materials with crystal water containing excipients nor for active ingredients. In this study, possible influence of crystal water was evaluated using lactose monohydrate and donepezil hydrochloride, an active pharmaceutical ingredient (API) against dementia. The study clearly showed that the contained hydrate does not cause interferences and is not monitored by the applied frequencies. Material-related limits measuring lactose monohydrate were only observed above typical granulation moistures and could be explained using raw resonance curves. Furthermore, the inclusion of donepezil hydrochloride into the monitored formulations and varied process parameters demonstrated the versatility of the microwave resonance sensor system. Inlet air temperature, spraying rate, and air flow were varied according to a 23 full factorial experimental design. A predictive model (R2= 0.9699, RMSEC = 0.33%) could be established using samples produced with different process parameter settings adjusted according to the corner points of the full factorial design and validated on the center point granulation processes (RMSEV = 0.38%). Thereby, performance on actual formulations and conditions faced during process development could be thoroughly assessed, and hence, another key requirement for applicability in formulation development could be met.

Quantitative Modeling of Phase Detection in Passive Inductively Coupled Resonant Sensors

We develop a model to quantify the signal strength in passive inductively coupled resonant sensor (PICRS) systems. We also explore the relationship between detectability and signal strength, which is critical for signal strength-sensitive applications. Either the phase or magnitude of the input impedance of a coupled reader can be used as a measurand; here, we focus on phase, but the model can be easily adapted to other measurands. The model employs dimensionless parameters, i.e., the quality factor ( $Q$ ) of the PICRS and coupling factor ( $k$ ) between the reader and PICRS. We experimentally verify the model using readers and sensors of different $Q$ and $k$ factors. The model incorporates the effect of the reader coil, which is essential for co-selection of readers and sensors. This model can find broader application as a tool for the design and detection of nonisochronous weakly coupled resonant sensors.

Noise of a JFET Charge Amplifier for Piezoelectric Sensors

A comprehensive noise model of a junction gate field-effect transistor (JFET) charge amplifier is presented for applications with piezoelectric sensors. Based on this previously reported amplifier structure, a noise equivalent circuit is derived and discussed. Universal noise gain expressions for each of the twelve considered noise sources are given. By means of an analytical description of the charge amplifier’s noise behavior, the design and optimization of such preamplifiers for various capacitive microelectromechanical sensor systems will be distinctly simplified. Calculations of the noise floor are compared with measurements with a cantilever-type magnetoelectric sensor and with the performance of a so far commonly utilized basic charge amplifier. With the JFET charge amplifier a noise reduction of approximately 22 dB is achieved in the vicinity of the utilized sensor’s resonance frequency of 7.45 kHz. The reported amplifier is the first which has no negative influence on the total noise level of a resonant magnetoelectric sensor system.

Prostate Cancer Detection with a Tactile Resonance Sensor-Measurement Considerations and Clinical Setup.

Tumors in the human prostate are usually stiffer compared to surrounding non-malignant glandular tissue, and tactile resonance sensors measuring stiffness can be used to detect prostate cancer. To explore this further, we used a tactile resonance sensor system combined with a rotatable sample holder where whole surgically removed prostates could be attached to detect tumors on, and beneath, the surface ex vivo. Model studies on tissue phantoms made of silicone and porcine tissue were performed. Finally, two resected human prostate glands were studied. Embedded stiff silicone inclusions placed 4 mm under the surface could be detected in both the silicone and biological tissue models, with a sensor indentation of 0.6 mm. Areas with different amounts of prostate cancer (PCa) could be distinguished from normal tissue (p < 0.05), when the tumor was located in the anterior part, whereas small tumors located in the dorsal aspect were undetected. The study indicates that PCa may be detected in a whole resected prostate with an uneven surface and through its capsule. This is promising for the development of a clinically useful instrument to detect prostate cancer during surgery.

Theoretical analysis of metamaterial-gold auxiliary grating sensing structure for surface plasmon resonance sensing application based on polarization control method

A metamaterial-gold multilayer sensing structure designed using the particle swarm optimization (PSO) algorithm with an auxiliary grating is proposed for using in a surface plasmon resonance (SPR) sensor system based on the polarization control method. After numerical calculations and simulation analysis, it was found that the metamaterial sensing structure significantly improves the sensitivity of the SPR signal with intensity singularity. The metamaterial sensing structure also increases the penetration depth of evanescent wave, making it possible to detect low-molecular-weight biomolecules and larger cells such as bacteria. The auxiliary grating structure was designed to identify the refractive index of the sensing region on both sides of intensity singularity. The stability of recognition and the electric field intensity of the visible light band were also studied.

Surface plasmon resonance sensing of a biomarker of Alzheimer disease in an intensity measurement mode with a bimetallic chip

A surface plasmon resonance (SPR) sensor system with a bimetallic chip has been utilized to sense the very low concentration of amyloid-beta (Aβ)(1-42) by measurement of the reflectance variation. The bimetallic chip was comprised of Au (10 nm) and Ag (40 nm) on Cr (2 nm)-coated BK-7 glass substrate. Protein A was used to efficiently immobilize the antibody of Aβ(1-42) on the surface of the bimetallic chip. The reflectance curve of the bimetallic chip represented a narrower linewidth compared to that of the conventional gold (Au) chip. The SPR sensor using the bimetallic chip in the intensity interrogation mode acquired the response of Aβ(1-42) at concentrations of 250, 500, 750 and 1,000 pg/ml. The calibration plot showed a linear relationship between the mean reflectance variation and the Aβ(1-42) concentration. The results proved that the SPR sensor system with the bimetallic chip in the intensity interrogation mode can successfully detect various concentrations of Aβ(1-42), including critical concentration, to help diagnose Alzheimer’s disease.

Biomimetic self-templating optical structures fabricated by genetically engineered M13 bacteriophage

Here, we describe a highly sensitive and selective surface plasmon resonance sensor system by utilizing self-assembly of genetically engineered M13 bacteriophage. About 2700 copies of genetically expressed peptide copies give superior selectivity and sensitivity to M13 phage-based SPR sensor. Furthermore, the sensitivity of the M13 phage-based SPR sensor was enhanced due to the aligning of receptor matrix in specific direction. Incorporation of specific binding peptide (His Pro Gln: HPQ) gives M13 bacteriophage high selectivity for the streptavidin. Our M13 phage-based SPR sensor takes advantage of simplicity of self-assembly compared with relatively complex photolithography techniques or chemical conjugations. Additionally, designed structure which is composed of functionalized M13 bacteriophage can simultaneously improve the sensitivity and selectivity of SPR sensor evidently. By taking advantages of the genetic engineering and self-assembly, we propose the simple method for fabricating novel M13 phage-based SPR sensor system which has a high sensitivity and high selectivity.

Tunable sensitivity phase detection of transmitted-type dual-channel guided-mode resonance sensor based on phase-shift interferometry.

This paper reports on a transmitted-type dual-channel guided-mode resonance (GMR) sensor system that uses phase-shifting interferometry (PSI) to achieve tunable phase detection sensitivity. Five interference images are captured for the PSI phase calculation within ∼15 s by using a liquid crystal retarder and a USB web camera. The GMR sensor structure is formed by a nanoimprinting process, and the dual-channel sensor device structure for molding is fabricated using a 3D printer. By changing the rotation angle of the analyzer in front of the camera in the PSI system, the sensor detection sensitivity can be tuned. The proposed system may achieve high throughput as well as high sensitivity. The experimental results show that an optimal detection sensitivity of 6.82×10(-4) RIU can be achieved.

Improving Sensitivity of Resonant Sensor Systems Through Strong Mechanical Coupling

This paper reports on the first use of strongly coupled microresonators to improve the sensitivity of resonant sensing systems. To date, the research on coupled resonant sensors has concentrated on weakly coupled systems, which rely on the measurement of signal amplitudes. Strongly coupled resonant sensor systems, on the other hand, provide a frequency-shift output that results in improved accuracy, precision, and dynamic range. A system model is developed to investigate the effect of perturbations on the eigenvalues of resonator arrays. The model is used to study the system sensitivity to perturbations as the coupling strength between the resonators is increased and demonstrates a multi-fold increase in sensitivity for strong coupling. The developed theory is employed to design strongly coupled resonant sensor systems. Proof-of-concept devices were fabricated in a custom microfabrication process that allowed for inclusion of piezoresistors on structural layers. Experimental results were used to validate the theoretical model and demonstrated an improvement of more than 20% in sensitivity with moderate coupling ratios. This paper lays the foundation for the design of strongly coupled resonant sensor systems for single or multiple measurands. [2015-0186]

Monitoring of the Dilution of Motor Oil with Diesel Using an Advanced Resonant Sensor System

In modern light-duty Diesel vehicles the particulate filters in the exhaust system require periodic regeneration to prevent plugging. The regeneration procedure is a major cause of dilution of engine oil with diesel fuel. In order to investigate the effect of the operation conditions of the engine on the fuel content in the oil, a precise and fast in-line measurement system is required. In this contribution a resonant sensor system for determination of diesel content by measuring the viscosity of the oil is tested. A commercial off-the-shelf quartz tuning fork resonator is used as sensor element and evaluated using a universal analyzer for resonant sensors developed for fast and precise acquisition of resonant sensor responses. The experiments presented in this paper show that fuel concentration in the range of 0.2 % can be determined within seconds. The obtained results are compared to that obtained with an accurate lab bench viscosity and mass density meter.

Clenbuterol Assay by Spectral Imaging Surface Plasmon Resonance Biosensor System.

To prevent illegal use of clenbuterol and for quality control in the food industry, more efficient and reliable methods for clenbuterol detection are needed. In this study, clenbuterol was detected using a spectral imaging surface plasmon resonance sensor system via two inhibition methods: (1) the target site compensation method, in which anti-clenbuterol antibody was immobilized on the sensor chip as a bioprobe and (2) the solution competition method in which a clenbuterol-BSA conjugate was immobilized on the sensor chip as the bioprobe. The detectable clenbuterol concentration ranged between 6.25 and 100μg/mL for both methods. The clenbuterol limit of detection for the target site compensation method and solution competition method are estimated to be 6.7 and 4.5μg/mL, respectively. The proposed methods were successfully applied to the detection of clenbuterol molecules and were found to have high specificity and high-throughput and were label free and operationally convenient.