scholarly journals Towards an Ultra Sensitive Hybrid Mass Sensor Based on Mode Localization without Resonance Tracking

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5295
Author(s):  
Claude Humbert ◽  
Vincent Walter ◽  
Najib Kacem ◽  
Thérèse Leblois
Keyword(s):  
Limit Of Detection ◽  
Open Loop ◽  
Fine Tuning ◽  
Mass Sensor ◽  
Fixed Frequency ◽  
Frequency Method ◽  
Frequency Tracking ◽  
Mode Localization ◽  
Resonant Structures ◽  
Peak Tracking

We present a mode localized mass sensor prototype based on a hybrid system excited at a fixed frequency slightly below the resonances. Indeed, we show, both theoretically and experimentally, that this condition yields higher sensitivities and similar sensitivity ranges than that of resonance peak tracking while being less time consuming than a classical open-loop configuration due to the absence of frequency sweep. The system is made of a quartz resonator and a hardware that includes a resonator and the coupling. The digital aspect allows maximum sensitivity to be achieved with a fine tuning of the different parameters and the implementation of a coupling, regardless of the physical resonator geometry. This allows the generation of mode localization on shear waves resonant structures such as the quartz cristal microbalance widely used in biosensing. This solution has been successfully implemented using resin micro balls depositions. The sensitivities reach almost their maximum theoretical values which means this fixed frequency method has the potential to reach lower limit of detection than the open loop frequency tracking method.

scholarly journals Equivalence of Open-Loop and Closed-Loop Operation of SAW Resonators and Delay Lines

Sensors ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 185 ◽  
Author(s):  
Phillip Durdaut ◽  
Michael Höft ◽  
Jean-Michel Friedt ◽  
Enrico Rubiola
Keyword(s):  
Closed Loop ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Noise Analysis ◽  
Open Loop ◽  
Sensor System ◽  
Electronic Systems ◽  
Delay Lines ◽  
Resonant Sensors ◽  
Closed Loop Systems

Surface acoustic wave (SAW) sensors in the form of two-port resonators or delay lines are widely used in various fields of application. The readout of such sensors is achieved by electronic systems operating either in an open-loop or in a closed-loop configuration. The mode of operation of the sensor system is usually chosen based on requirements like, e.g., bandwidth, dynamic range, linearity, costs, and immunity against environmental influences. Because the limit of detection (LOD) at the output of a sensor system is often one of the most important figures of merit, both readout structures, i.e., open-loop and closed-loop systems, are analyzed in terms of the minimum achievable LOD. Based on a comprehensive phase noise analysis of these structures for both resonant sensors and delay line sensors, expressions for the various limits of detection are derived. Under generally valid conditions, the equivalence of open-loop and closed-loop operation is shown for both types of sensors. These results are not only valid for SAW devices, but are also applicable to all kinds of phase-sensitive sensors.

scholarly journals Noise Immunity Analysis and Improvement of dq Frame Based Open-Loop Phase Detection Scheme

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1145
Author(s):  
Xiaobo Li ◽  
Mingxian Li ◽  
Hua Chai ◽  
Binbing Wu
Keyword(s):  
High Frequency ◽  
Noise Immunity ◽  
Open Loop ◽  
Fine Tuning ◽  
Frequency Noise ◽  
Phase Detection ◽  
Detection Error ◽  
Pass Filter ◽  
High Frequency Noise ◽  
Grid Voltage

To improve the noise immunity of a dq frame based open-loop phase detection (OPD) under high-frequency noise grid conditions, this paper develops a detailed model to quantitatively evaluate the phase detection error and noise immunity. It is found that the OPD behaves differently in terms of noise immunity when the dq frame is in different angle positions with the grid voltage. When the grid voltage coincides with the d axis, the high-frequency noise has the smallest impact on the phase detection accuracy, and the OPD thus has the strongest noise immunity. Inspired by this conclusion, an improved OPD algorithm is proposed in this paper, which can effectively reduce the phase detection error by fine-tuning the rotation angle of the dq frame to ensure that the angle between the voltage vector and d axis is always close to 0. The improved OPD algorithm has a fast and precise character to detect the phase information with less error and is flexible for application. Under heavy noise grid conditions, it can also effectively shorten the dynamic response time in the phase-detecting process using a low-pass filter (LPF) with a higher cut-off frequency. The correctness of the noise immunity analysis and the effectiveness of the improved OPD algorithm are verified by the simulations and experimental results in MATLAB and RT-LAB.

Determination of sub-picomolar levels of platinum in the pristine Krka River estuary (Croatia) using improved voltammetric methodology

2020 ◽  
Vol 17 (2) ◽  
pp. 77 ◽  
Author(s):  
Jasmin Pađan ◽  
Saša Marcinek ◽  
Ana-Marija Cindrić ◽  
Nicolas Layglon ◽  
Cedric Garnier ◽  
...  
Keyword(s):  
Natural Waters ◽  
Limit Of Detection ◽  
Small Deviation ◽  
Salinity Gradient ◽  
River Estuary ◽  
Stripping Voltammetry ◽  
Fine Tuning ◽  
Surface Active ◽  
Dissolved Form ◽  
Active Substances

Environmental contextPlatinum concentrations in natural waters such as oceans, rivers and lakes are extremely low, hindering studies of Pt distributions and biogeochemical cycles. An improved electrochemical method was used to reliably determine Pt in estuarine conditions at trace concentrations. Platinum displayed a near-conservative behaviour along the salinity gradient of the estuary, with about 90% remaining in the dissolved form. AbstractExtremely low concentrations of platinum in natural waters require very sensitive analytical techniques, with adsorptive cathodic stripping voltammetry (AdCSV) being one of the most frequently used techniques. A ‘fine tuning’ of the voltammetric parameters, along with advanced data treatment based on derivative transformations, allowed us to determine reliably Pt levels down to 50 fM (0.05 pM). By using short modulation and interval times of the differential pulse stripping waveform, and applying a 4th derivative transformation to the voltammograms, the limit of detection (LOD) was lowered down to 10 fM. Although very small concentrations of surface-active substances (e.g. 0.025mgL−1 fulvic acid) strongly influenced the method sensitivity, recoveries of spiked samples were not impacted (~100%). The application of a desorption step (Eds=−1.35V; tds=2s) at the end of the accumulation significantly improved the sensitivity, presumably through the removal of adsorbed surface-active substances. Using this optimised methodology, we determined the Pt distribution in the pristine Krka River estuary in the winter and summer periods by performing both horizontal transects and vertical profiles (salinity ~1 to 39). In surface waters, dissolved Pt concentrations gradually increased towards the seawater end-member (from ~0.15 to ~0.3 pM). A small deviation from the conservative mixing line was observed at salinities below 10, which may reflect changes in Pt redox speciation. In bottom waters, the trend was opposite with dissolved Pt concentrations increasing towards the freshwater end-member, probably owing to progressive accumulation related to seawater residence time. On average, 90% of Pt was present in the dissolved form.

scholarly journals An asymmetric mode-localized mass sensor based on the electrostatic coupling of different structural modes with distributed electrodes

2021 ◽  
Author(s):  
Jiahao Song ◽  
Ming Lyu ◽  
Najib Kacem ◽  
Jian Zhao ◽  
Pengbo Liu ◽  
...  
Keyword(s):  
Amplitude Ratio ◽  
Harmonic Balance Method ◽  
Nonlinear Behavior ◽  
Mass Sensor ◽  
Mass Detection ◽  
Coupled Resonators ◽  
Critical Amplitude ◽  
Asymmetric Mode ◽  
Mode Localization ◽  
Electrostatic Coupling

Abstract Mode-localization sensor with amplitude ratio as output metric has shown excellent potential in the field of micro-mass detection. In this paper, an asymmetric mode -localized mass sensor with a pair of electrostatically coupled resonators of different thickness is proposed. Partially distributed electrodes are introduced to ensure the asymmetric mode coupling of second and third order modes while actuating the thinner resonator by the distributed electrode. The analytical dynamic model is established by Euler–Bernoulli theory and solved by harmonic balance method (HBM) combined with asymptotic numerical method (ANM). Detailed investigations on the linear and nonlinear behavior, critical amplitude as well as the sensitivity of the sensor are performed. The sensitivity of the proposed sensor can be enhanced by about 20 times compared to first order mode-localized mass sensors. Furthermore, by exploiting the nonlinearities while driving the device beyond the critical amplitude for the in-phase mode, the sensor performs a great improvement in sensitivity up to 1.78 times. Besides, the influence of the decrease of coupling voltage is studied, which gives a good reference to avoid mode aliasing.

Development of Adaptive Feed-Forward Cancellation With Frequency Estimation Algorithm for Compensation of Periodic Disturbance at Arbitrary Frequency

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Shota Yabui ◽  
Tsuyoshi Inoue
Keyword(s):  
Real Time ◽  
Frequency Estimation ◽  
Estimation Algorithm ◽  
Open Loop ◽  
Fixed Frequency ◽  
Nyquist Diagram ◽  
Feed Forward ◽  
Periodic Disturbance ◽  
Arbitrary Frequency ◽  
The Stability

Abstract In this study, an adaptive feed-forward cancellation (AFC) with frequency estimation algorithm has been developed to compensate for periodic disturbance at an arbitrary frequency. Conventional AFC was developed to compensate for periodic disturbance at a fixed frequency and cannot compensate for the disturbance in which the frequency varies in real-time. The proposed method can estimate the frequency of the disturbance in real-time by using the input and output signals of the AFC. It can compensate for the periodic disturbance at an arbitrary frequency. In addition, the stability of the feedback control system with the proposed AFC can be optimized at any frequency based on the vector locus of the open-loop characteristic on the Nyquist diagram. The effectiveness of the proposed AFC was confirmed in experiments compensating for whirling vibration, whose frequency varies in real-time in rotating machinery. The proposed AFC can estimate the frequency of the disturbance automatically and compensate for this adequately.

A novel capacitive mass sensor using an open-loop controlled microcantilever

2020 ◽  
Vol 26 (9) ◽  
pp. 2977-2987
Author(s):  
R K Godara ◽  
Atul Kumar Sharma ◽  
Nishu Joshi ◽  
M M Joglekar
Keyword(s):  
Open Loop ◽  
Mass Sensor

scholarly journals РЕШЕНИЕ ЗАДАЧИ СТАБИЛИЗАЦИИ ТЕМПЕРАТУРЫ ВОЗДУХА В КАБИНЕ ТРАНСПОРТНОГО СРЕДСТВА

2018 ◽  
pp. 12-19
Author(s):  
Сергей Николаевич Пасичник ◽  
Дмитрий Вадимович Сокол
Keyword(s):  
Steady State ◽  
Thermal Load ◽  
Transfer Functions ◽  
Open Loop ◽  
Frequency Characteristics ◽  
Temperature Stabilization ◽  
Frequency Method ◽  
Vehicle Cabin ◽  
Static Calculation

The subject matter of the article is the processes of synthesis of the automatic stabilization system (ASS) of the temperature in the vehicle cabin simulator using the vortex energy separator (VES) as the executive element of the system. The goal is to correct element synthesis of the ASS (CEs), which provides stability and quality of stabilization with the intensive change in the thermal load. The tasks to be solved are: to construct the functional scheme of the ASS which consist of the positioning circuit of the modes of the VES and the air temperature stabilization circuit in the cabin simulator; applying the results of solving the problem of synthesis of the automatic positioning system (APS) of modes of the VES, construct the structural diagram and mathematical model of the ASS of the temperature in the form of interval transfer functions (TF); perform the static calculation of the system to ensure the accuracy in steady-state and transient modes with linearly varying input influences; solve the problem of ensuring stability and dynamic levels of quality of the temperature stabilization using interval logarithmic amplitude-frequency characteristics (LAFC) and indirect levels of quality of the system's functioning in the frequency domain. The applied methods are: LAFC, real frequency characteristics. The following results were obtained: the functional and structural schemes of the ASS of the temperature in the vehicle cabin simulator are constructed, the interval transfer functions of the open-loop and closed-loop system are determined according to the referencing and disturbing influences. The static calculation of the system is performed to determine the required value of the transfer coefficient of the open-loop ASS based on the condition of ensuring the accuracy of the system in the steady-state mode of operation and with the intensive change in the thermal load. The dynamic calculation of the system was performed, as a result of which the structure and parameters of the CEs were determined based on the analysis of the dependence of the phase stability margin and the cut-off frequency on the values of the parameters of the CEs in accordance with the requirements for dynamic levels of quality. Conclusions. The scientific novelty of the results obtained is following: the frequency method of synthesis of the ASS using interval LAFC has been further developed by investigating the behavior of the logarithmic characteristics on the boundaries of the intervals of parameters of the transfer function of close-loop APS of the of the VES

scholarly journals Mass sensor using mode localization in two weakly coupled MEMS cantilevers with different lengths: Design and experimental model validation

2019 ◽  
Vol 295 ◽  
pp. 643-652 ◽  
Author(s):  
Toky Rabenimanana ◽  
Vincent Walter ◽  
Najib Kacem ◽  
Patrice Le Moal ◽  
Gilles Bourbon ◽  
...  
Keyword(s):  
Experimental Model ◽  
Model Validation ◽  
Mass Sensor ◽  
Mode Localization ◽  
Weakly Coupled ◽  
Mems Cantilevers

scholarly journals Principal factors that determine the extension of detection range in molecular beacon aptamer/conjugated polyelectrolyte bioassays

2015 ◽  
Vol 6 (3) ◽  
pp. 1887-1894 ◽  
Author(s):  
Ji-Eun Jeong ◽  
Boram Kim ◽  
Shinjae Woo ◽  
Sungu Hwang ◽  
Guillermo C. Bazan ◽  
...  
Keyword(s):  
Molecular Beacon ◽  
Limit Of Detection ◽  
Fine Tuning ◽  
Detection Range ◽  
Conjugated Polyelectrolyte ◽  
Principal Factors ◽  
New Bioassay

A new bioassay strategy based on the molecular beacon aptamer/conjugated polyelectrolyte demonstrates a fine-tuning of the detection range and limit of detection for weakly-binding targets.

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