High Linearity Research Articles

Neuromorphic alternating current sensing using piezoelectric resonators and physical reservoir computing

Non-contact current sensors are valuable because they can safely measure alternating current without interrupting the circuit. However, current sensors utilizing Hall elements or coils are only available for single wires, and piezoelectric resonator-based sensors have difficulty achieving both high sensitivity and linearity. To address this issue, we propose a novel approach, that is, the use of piezoelectric current sensors as nodes for physical reservoir computing (physical RC), allowing us to utilize nonlinear regions. To improve the sensitivity and short-term memory required by physical RC, a piezoelectric resonator with a quality factor of 75 was realized by employing a tuning fork structure. Nonlinearities were also introduced by analog circuits. The results of the benchmark tests indicate that the device worked as a physical RC and that it successfully predicted unknown current values from the results of training at three levels of current.

Prophet modeling for oil production forecasting in an enhanced oil recovery field

Accurate daily oil production forecasting is essential for efficient reservoir management and investment strategy. Forecasting oil production in enhanced oil recovery (EOR) and conformance-dominated fields is a complex process due to the nonlinear, voluminous, and often uncertain nature of reservoir parameters and hidden factors. As a result, conventional tools such as decline curve analysis frequently fail to accurately predict daily oil production in conformance-controlled areas. In contrast, machine learning works efficiently for large datasets, even if the parameter values are unknown. The current study employs a Prophet time series forecasting method for five oil production wells in an EOR applied field, but it fails to achieve the desired sweep efficiency. This study compares the results of conventional decline curve analysis (DCA) and popular autoregressive integrated moving average time series forecasting methods with the Prophet model. This is the first attempt to use Prophet for oil well production forecasting, where polymer flooding is used. In all, 60% of the data are used for training, and the remaining 40% are used for testing. The Prophet shows the best performance for all the wells. This study is also the first to handle shut-in data using the Prophet model for oil production. Well-2 achieves the highest accuracy after incorporating shut-in results, with an R2 score of 92%. The result shows that though the DCA performs reasonably well with higher linearity and trend stationary data, Prophet modeling shows superior results than conventional DCA for all EOR applied producing wells.

Curing and Failure Monitoring of Composite Material Single-Lap Joint Based on CNT/PSF Sensor

Abstract Composite bonded structures are widely used in the field of aerospace. The safety of composite structures can be ensured by the health monitoring and early warning of their whole life. In this paper, a composite CNT/PSF film sensor based on asymmetric porous PSF film was designed and prepared. Through integrated molding with epoxy film, in-situ monitoring of gel point (142.1°C) and curing time (36min) of epoxy film is realized. After optimization of curing process, tensile strength of epoxy film casting body is increased by 86.3%. The single lap shear strength of the composite is increased by 45.7%. The CNT/PSF film sensor with composite material has high response sensitivity (GF≈1.4) and linearity (0.998) to cyclic strain (0-3000με). In the shear experiment of composite single lap joint, the adhesive layer presents a typical cohesive failure mode of first compression, then tensile and finally failure. The resistance changes of CNT/PSF film sensor first decreases from 0 to -1‰, and then rises to 2.7‰. Finally, the fracture response is good, and the in-situ failure behavior monitoring of the joint can be fully realized.

Visual Dose Monitoring for Whole Breast Radiation Therapy Treatments via Combined Cherenkov Imaging and Scintillation Dosimetry

PurposeThis study investigates scintillation dosimetry coupled with Cherenkov imaging for in vivo dose monitoring during whole breast radiotherapy (WBRT). Given recent observations of excess dose to the contralateral breast (CB), in vivo dosimetry (IVD) could help ensure accurate dose delivery and decrease risks of secondary cancer. This work presents a rapid, streamlined alternative to traditional IVD, providing direct visualization of measurement location relative to the treatment field on the patient. Methods and Materials10 WBRT patients consented under an IRB-approved protocol were monitored with scintillation dosimetry and always-on Cherenkov imaging, on both their treated and CB for one to three fractions. Scintillator dosimeters, small plastic discs 1mm thick and 15mm in diameter, were calibrated against optically-stimulated luminescent dosimeters (OSLDs) to generate an integral output-to-dose conversion, where integral output is measured in post-processing through a custom fitting algorithm. The discs have been extensively characterized in a previous study for various treatment conditions including beam energy and treatment geometry. ResultsN=44 dosimetry measurements were evaluated, including 22 treated breast and 22 CB measurements. Following integral output-to-dose calibration, in vivo scintillator dosimeters exhibited high linearity (R2=0.99) with paired OSLD readings across all patients. The difference between scintillation and OSLD dose measurements averaged 2.8% of the prescribed dose, or an absolute dose difference of approximately 7 cGy. ConclusionsIntegration of scintillation dosimetry with Cherenkov imaging offers an accurate, rapid alternative for in vivo dose verification in WBRT, circumventing the limitations of conventional point dosimeters. The additional benefit of visualizing measurement locations relative to the treatment field provides users an enhanced understanding of results and allows for detection of high dose gradients. Future work will explore the applicability of this technique across a broader range of radiotherapy treatments, aiming to streamline IVD practices.

Tunable terahertz meta-resonator with switchable single- and dual-resonance characteristic

A tunable terahertz meta-resonator (TTM) is proposed to be capable of switching single- and dual-resonance characteristics in this article. The presented TTM device consists of two symmetrical E-shaped electric split-ring resonators (eSRRs) on the silicon (Si) substrate. Through the change of the gap between two eSRRs, it allows the resonances to be tuned about 78 GHz, spanning from 0.780 THz to 0.702 THz in transverse magnetic (TM) mode. When one eSRR is anchored on the Si substrate and the other suspended eSRR is heightened along the z-axis direction, the TTM device exhibits resonance-insensitive behavior in transverse electric (TE) mode, along with a convertible feature that enables it to transition between single-resonance and dual-resonance responses in TM mode. Besides, the practicality of TTM device is further enhanced by its capability to operate effectively in ambient surroundings with varying refractive indexes. In TE and TM modes, the high linearity relationship between resonances and refractive indexes is achieved with correlation coefficients both exceeding 0.99. The TTM device provides potential possibilities in tunable filters, switchable logic gates, environmental sensors, and other dynamically controllable THz-wave optoelectronics devices.

A novel fluorescence sensing strategy for identification and quantitation of C60 and C70 by multi-emission lanthanide-disalicylaldehyde hybrid

Till now, there is still a lack of the convenient and efficient approach to implement identification and quantitation of fullerenes in various domains. This work provides the first example for detecting fullerenes by an adequate fluorescent probe, in parallel with the new methodology for detecting fullerenes by the fluorescent chemosensing approach. Using a multi-emission lanthanide-disalicylaldehyde coordination hybrid H2Qj2/Tb0.91Eu0.09, the rapid, selective and discriminative detection of analogous C60 and C70 can be easily achieved after the spectral and statistical analyses of fluorescent sensing signals on four emission bands (416, 543, 447 and 615 nm), excited by two irradiation lights (370 and 394 nm). Titration experiments further verify the very high linearity for both C60 and C70 and allow their detection at concentrations as low as 1.72 μM (C60) and 0.09 μM (C70). Moreover, this fluorescent probe also shows its reliable abilities to identify proportional C60/C70 mixtures and monitor C60 and C70 contents in actual soil sample. It is believed that our proposed lanthanide-base fluorescent matrix not only verify the feasibility and potential of fluorescent chemosensing methodology for the fullerene detection but also provide a valuable tool for potential applications.

Quantitative analysis of selected alkaloids of Mitragyna speciosa using 1H quantitative nuclear magnetic resonance spectroscopy.

Mitragyna speciosa is a perennial plant native to Asia, well known for its psychoactive properties. Its major alkaloid mitragynine is known to have sedative and euphoric effects. Hence, the plant has been a subject of abuse, leading to addiction, necessitating efficient analytical methods to detect its psychoactive constituents. However, current chromatography-based methods for detecting the alkaloids are time consuming and costly. Quantitative nuclear magnetic resonance (qNMR) spectroscopy emerges as a promising alternative due to its nondestructive nature, structural insights, and short analysis time. Hence, a rapid and precise qNMR method was developed to quantify selected major psychoactive alkaloids in various parts of M.speciosa. Mitragynine, specioliatine, and speciogynine were quantified in relation to the integral value of the -OCH3 groups of the alkaloids and the internal standard 1,4-dinitrobenzene. The precision and reproducibility of the method gave a relative standard deviation (RSD) of 2%, demonstrating the reliability of the method. In addition, the method showed excellent specificity, sensitivity, high linearity range (R2 = 0.999), and limits of detection (LOD) and quantification (LOQ) values. The analysis revealed that the red-veined M.speciosa leaves contained higher levels of mitragynine (32.34 mg/g), specioliatine (16.84 mg/g) and speciogynine (7.69 mg/g) compared to the green-veined leaves, stem bark, or fruits.

Linear Bloch-Siegert phase-encoded low-field MRI: RF coils, pulse sequence, and image reconstruction.

Conventional gradient systems have several weaknesses including high cost and bulk. As a step towards addressing these while providing new degrees of freedom for spatial encoding and system design in Magnetic Resonance Imaging (MRI), a radio frequency (RF) gradient encoding system and pulse sequence for phase encoding using the Bloch-Siegert (BS) shift were developed. Optimized BS spatial encoding coils with bucking windings (counter-wound loops) were designed and constructed, along with compatible homogeneous imaging coils for excitation and signal reception. Two coil systems were developed: one for phantom imaging and a second for human wrist imaging. BS phase-encoded imaging and BS RF pulse simulations were performed. Pulse sequences were designed for linear stepping in k-space and implemented on a 47.5-mT scanner to image resolution phantoms in both coil setups. Reconstructions were performed using both the full -based encoding fields for each BS pulse amplitude and using inverse discrete Fourier transforms. A gradient was used for frequency encoding during signal readout, and the third axis was projected. Specific absorption ratio (SAR) calculations were performed for the wrist coil to determine the safety of BS-based RF encoding for fields in the low field MRI regime. The optimized RF spatial encoding coils resulted in higher linearity ( and 0.9921 in the phantom and wrist coils, respectively) than coils used in previous work. The phantom and wrist imaging coils were validated in simulations and experimentally to produce a peak G and 0.8 G with 12-W input power, respectively, in the field-of-view (length = 11 cm) used for imaging. Nominal imaging resolutions of 5.22 and 7.21 mm were, respectively, achieved by the two-coil systems in the RF phase-encoded dimension. Coil systems, pulse sequences, and image reconstructions were developed for linear RF phase encoding using the BS shift and validated using a 47.5-mT open low field scanner, establishing a key component required for gradient-free imaging at low field strengths.

Microscale Humidity Sensor Based on Iron-Coated Elaters of Equisetum Spores.

Humidity sensors deeply influence human manufacturing production and daily life, while researchers generally focus on developing humidity sensors with higher stability, higher linearity, rapid response time, etc. Yet, few people discuss measuring humidity in the microenvironment by miniaturizing sensor size into a microscale, in which the existing humidity sensors are difficult to reach. Accordingly, this study proposes a methodology for measuring relative humidity in the microscale by utilizing the distinctive morphologies of Equisetum spores across a range of relative humidities between 50% and 90%. Equisetum spores are responsive to changes in ambient relative humidity and remain in their original activities even after iron sputtering, which aims to endow the sensor with magnetic properties. The test performed in this study demonstrated a response time of 3.3 s and a recovery time of 3.6 s. In the first application, we employed such microscale sensors to work in the channel of the microfluidic chip or the cell migration microchip, as an example of working in the microenvironment. COMSOL Multiphysics 6.2 software was also used to simulate the change in relative humidity in such microchannels. Secondly, such microscale sensors are combined with smartphone-based microscopy to measure the humidity of the skin. These microscale sensors pave the new way to sensing humidity in microenvironments.

Structural design and performance testing of respiratory sensor based on optical fiber end-face coupling

An optical fiber sensor based on the principle of intensity modulation is proposed, which is composed of plastic optical fibers and silicone tubes. The displacement measurement is achieved by stretching the optical fibers to cause changes in the angle between the end faces, resulting in changes in the coupling efficiency between the end faces. To address the challenges in the performance calibration of fiber optic respiratory sensors, it is proposed to convert the dynamic characteristics measurement of the respiratory sensor into the static performance analysis of the displacement sensor, so as to obtain the characteristics such as sensitivity, linearity, and repeatability, etc. It is further proposed to use a stepper motor to simulate the periodic stretching process of the optical fibers caused by the respiratory process, enabling the analysis of frequency measurement accuracy under different respiratory strengths. Simulation and experimental results demonstrate that the proposed sensor has high linearity, good repeatability, high sensitivity, and a wide measurement range. It can accurately measure respiratory frequency and display amplitude information, providing comprehensive information for respiratory monitoring.

Performance Study of F-P Pressure Sensor Based on Three-Wavelength Demodulation: High-Temperature, High-Pressure, and High-Dynamic Measurements.

F-P (Fabry-Perot) pressure sensors have a wide range of potential applications in high-temperature, high-pressure, and high-dynamic environments. However, existing demodulation methods commonly rely on spectrometers, which limits their application to high-frequency pressure signal acquisition. To solve this problem, this study developed a self-compensated, three-wavelength demodulation system composite with an F-P pressure sensor and a thermocouple to construct a comprehensive sensing system. The system produces accurate pressure measurements in high-temperature, high-pressure, and high-dynamic environments. In static testing at room temperature, the sensing system shows excellent linearity, and the pressure sensitivity is 158.48 nm/MPa. In high-temperature testing, the sensing system maintains high linearity in the range of 100 °C to 700 °C, with a maximum pressure-indication error of about 0.13 MPa (0~5 MPa). In dynamic testing, the sensor exhibits good response characteristics at 1000 Hz and 5000 Hz sinusoidal pressure frequencies, with a signal-to-noise ratio (SNR) greater than 37 dB and 45 dB, respectively. These results indicate that the sensing system proposed in this study has significant competitive advantages in the field of high-temperature, high-speed, and high-precision pressure measurements and provides an important experimental basis and theoretical support for technological progress in related fields.

Laser Fabrication of Humidity Sensors on Ethanol-Soaked Polyimide for Fully Contactless Respiratory Monitoring.

Humidity-sensor-based fully contactless respiratory monitoring can eliminate the discomfort and infection risks associated with any wearable device. However, challenges in the facile fabrication of highly sensitive humidity sensors continue to hinder their widespread application for fully contactless respiratory monitoring. In this study, we introduce a simple method to fabricate highly sensitive humidity sensors. Our method employs laser-induced graphene (LIG) on an ethanol-soaked polyimide (PI) film as the electrode of the humidity sensor. The ethanol-soaked PI between adjacent LIG electrodes functions as the sensing material, enabling ion-conductive humidity sensing. Compared to the LIG humidity sensors fabricated on untreated PI films, LIG humidity sensors fabricated on ethanol-soaked PI films exhibit superior performance with higher linearity (R2 = 0.9936), reduced hysteresis (ΔH = 5.1% RH), and increased sensitivity (0.65%/RH). Notably, the LIG humidity sensor fabricated on the ethanol-soaked PI film can detect a person's breathing from a distance of 30 cm, a capability not achieved by sensors fabricated on untreated PI films. Moreover, incorporating these LIG humidity sensors into an array further enhances both the detection distance and the sensitivity for respiratory monitoring. Experimental results demonstrate that the LIG humidity sensor array can be employed for fully contactless on-bed respiration monitoring and for continuous, fully contactless monitoring of the respiratory rate during treadmill exercise. These results highlight the great potential of our LIG humidity sensors for various practical applications in medicine and sports.

Total reflection x‐ray fluorescence analysis of trace elements in highly saline samples

AbstractThe reliable trace analysis of high‐purity chemicals and environmentally relevant samples is more important than ever and has led to the development of novel analytical methods. Total reflection x‐ray fluorescence (TXRF) analysis is an increasingly known method for the determination of heavy metals at low concentration levels in environmental and industrial sample systems. However, there is still a need for optimization to obtain fast and precise results, especially for highly saline samples like brines and salts used in battery production or sea water. In this study, multi‐element standard solutions containing analytes like Co, Cr, Cu, Fe, Mn, Ni, or Zn in a concentration range between 0.1 and 1 mg/L were analyzed in the matrices lithium carbonate (Li2CO3) and artificial seawater (ASW) containing 1000 mg/L Li and 24,000 mg/L NaCl, respectively, leading to matrix‐analyte ratios of up to 240,000:1. Different sample preparation methods were compared in order to achieve the highest possible repeatability (1) and signal‐to‐noise ratios (2) with the least amount of time (3). Various parameters such as sample volume, drying conditions, time, temperature and additive concentration were varied. The relative standard deviation (RSD%) was used as a measure of repeatability for three replicates per sample. For lithium carbonate, a method with a preparation time of only 2 min and a measurement time of 500 s could be developed, which allowed to obtain RSD% well below 5%, a high linearity (R2 > 0.99) and limits of detection (LOD) in the range of 30 μg/L to 60 μg/L for most elements. Seawater analysis could be optimized with respect to signal‐to‐noise ratio, whereby the Kα‐line of the internal standard (Ga) was used for evaluation and the use of a desiccator was found to yield the best results.

The Design, Simulation, and Parametric Optimization of an RF MEMS Variable Capacitor with an S-Shaped Beam

This study presents the design and simulation of an RF MEMS variable capacitor with a high tuning ratio and high linearity factor of capacitance–voltage response. An electrostatic torsion actuator with planar and non-planar structures is presented to obtain the high tuning ratio by avoiding the occurrence of pull-in point. In the proposed design, the capacitor plate is connected to the electrostatic actuators by using the s-shaped beam. The proposed design shows a 138% tuning ratio with the planar structure of the actuator and 167% tuning ratio by implementing the non-planar structure. A linearity factor of 99% is attained by adjusting the rates at which the capacitor plate rises as the actuation voltage increases and the rate at which the capacitance decreases as the plate rises. Parametric optimization of the design is performed by utilizing the finite element method (FEM) analysis and high-frequency structural simulator (HFSS) analysis to obtain an optimized high-tuning ratio RF MEMS varactor at low actuation voltage. S-parameters of the design are presented on HFSS, with a 50 ohm coplanar waveguide (CPW) serving as the transmission line. The proposed RF MEMS varactor can be utilized in tunable RF devices.

A polyester- stainless steel based smart wristband sensor for skin temperature monitoring

This study presents the development and characterization of a novel textile-based wristband sensor for continuous temperature monitoring. The sensor, woven with a blend of polyester-stainless steel and polyester-cotton yarns, exhibited high sensitivity (0.0315/°C) and a rapid response time (∼35 sec). Stainless steel was selected for its excellent electrical conductivity and biocompatibility, crucial for accurate and safe skin contact applications, while polyester and cotton contribute its lightweight, breathable, and durable properties, ensuring prolonged comfort and wearability. Through systematic testing and optimization, the sensor’s sensitivity was fine-tuned by adjusting the number and length of conductive yarns. The study also introduced a theoretical resistance equivalent model, comparing its theoretical sensitivity with experimental findings. The sensor, lightweight and cost-effective, proved comfortable during 8–10 h of continuous wear. This study addresses challenges faced by existing textile temperature sensors and offers a reliable alternative with high linearity, repeatability, and suitability for individuals with sensitive skin.

Determination of Choline-Containing Compounds in Rice Bran Fermented with Aspergillus oryzae Using Liquid Chromatography/Tandem Mass Spectrometry.

Choline-containing compounds are essential nutrients for human activity, as they are involved in many biological processes, including cell membrane organization, methyl group donation, neurotransmission, signal transduction, lipid transport, and metabolism. These compounds are normally obtained from food. Fermented brown rice and rice bran with Aspergillus oryzae (FBRA) is a fermented food product derived from rice and rice ingredients. FBRA exhibits a multitude of functional properties with respect to the health sciences. This study has a particular focus on choline-containing compounds. We first developed a simultaneous liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis method for seven choline-containing compounds. The method was subsequently applied to FBRA and its ingredients. Hydrophilic interaction chromatography (HILIC) and selected reaction monitoring were employed for the simultaneous analysis of seven choline-containing compounds. MS ion source conditions were optimized in positive ion mode, and the product ions derived from the choline group were obtained through MS/MS optimization. Under optimized HILIC conditions, the peaks exhibited good shape without peak tailing. Calibration curves demonstrated high linearity across a 300- to 10,000-fold concentration range. The application of the method to FBRA and other ingredients revealed significant differences between food with and without fermentation. In particular, betaine and α-glycerophosphocholine were found to be highest in FBRA and brown rice malt, respectively. The results indicated that the fermentation processing of rice ingredients results in alterations to the choline-containing compounds present in foods. The developed HILIC/MS/MS method proved to be a valuable tool for elucidating the composition of choline-containing compounds in foods.

A high-performance wearable microneedle sensor based on a prussian blue-carbon nanotube composite electrode for the detection of hydrogen peroxide and glucose

Hydrogen peroxide (H2O2) plays an important role in biology, and biomarker detection in skin interstitial fluid (ISF) has recently shown great promise. However, limited sensors were designed for H2O2 detection in ISF. Therefore, a high-performance wearable H2O2 microneedle sensor with a Prussian blue (PB)/carbon nanotube (CNT) composite electrode and a glucose microneedle sensor based on this electrode were developed. Two types of H2O2 microneedle sensors with different CNT and PB ratios were prepared with ultra-wide detection ranges (1 μΜ–2800 mM/100 nΜ–2200 mM) in accordance with the Hill equation. Ultra-high sensitivity (954.1 μA mM−1 cm−2 and 451 μA mM−1 cm−2) and excellent linearity (R2=0.999) were exhibited in linear ranges of 1 μM to 10 mM and 100 nM to 10 mM, respectively·H2O2 sensors exhibit good selectivity and essentially unattenuated detection signals in artificial ISF. The glucose enzyme-catalyzed microneedle sensor based on the CNT/PB composite electrode also exhibited a great detection range (0.5 mM–180 mM) in accordance with the Hill equation and ultra-wide linear range (0.5 mM–40 mM) with high sensitivity (16.56 μA mM−1 cm−2) and linearity (R2=0.995) in artificial ISF. To verify the practical applicability of the sensors, H2O2 levels in normal and tumor cells were successfully detected by the H2O2 sensor. The glucose levels in ISF before and after eating were successfully detected by the glucose sensor in vivo. The present work developed a low-cost, easy-to-prepare H2O2 sensor and a related enzyme-catalyzed sensor with excellent performance, which hold promising prospects for application across diverse fields.

Miniature fiber optic SPR high sensitivity humidity sensor based on coated polyvinyl alcohol film

For the measurement of relative humidity, this study employed Surface Plasmon Resonance (SPR) technology, a sensor with a micro-conical fiber structure (sensing length is only 375 μm) was combined with Polyvinyl Alcohol (PVA) to create a humidity sensor that is highly sensitive, compact, dense, and exhibits good linearity. The humidity sensor is based on a gold film (thickness of about 40 nm) on the surface of the miniature fiber optic structure, and by applying PVA coating, the SPR humidity sensor shows resonance peaks in the transmission spectrum in ambient air, and as the number of layers of PVA coating (thickness) is added, the resonance peaks’ positions are red-shifted. The experimental findings demonstrated that this SPR humidity sensor’s sensitivity was 0.162 nm/%RH at an initial resonance wavelength of about 550 nm (one layer) and about 1.542 nm/%RH at an initial resonance wavelength of 656 nm (five layers) in the range of 46 %RH to 93 %RH. The wavelength and the relative humidity had a good linear connection. Temperature tests revealed the sensor has a −0.152 nm/°C temperature sensitivity between 20 °C and 50 °C and has a high linearity (0.999). Therefore, the sensor has potential applications in humidity measurement.

Development of a Methodology Based on Optical Interferometry for Measuring Fibrinolytic Activity.

Fibrinolytic activity assay is particularly important for the detection, diagnosis, and treatment of cardiovascular disease and the development of fibrinolytic drugs. A novel efficacious strategy for real-time and label-free dynamic detection of fibrinolytic activity based on ordered porous layer interferometry (OPLI) was developed. Fibrin or a mixture of fibrin and plasminogen (Plg) was loaded into the highly ordered silica colloidal crystal (SCC) film scaffold to construct a fibrinolytic response interference layer to measure fibrinolytic activity with different mechanisms of action. Fibrinolytic enzyme-triggered fibrinolysis led to the migration of interference fringes in the interferogram, which could be represented by optical thickness changes (ΔOT) tracked in real time by the OPLI system. The morphology and optical property of the fibrinolytic response interference layer were characterized, and the Plg content in the fibrinolytic response interference layer and experimental parameters of the system were optimized. The method showed adequate sensitivity for the fibrinolytic activity of lumbrokinase and streptokinase, with wide linear ranges of 12-6000 and 10-2000 U/mL, respectively. Compared with the traditional fibrin plate method, it has a lower detection limit and higher linearity. The whole kinetic process of fibrinolysis by these two fibrinolytic drug models was recorded in real time, and the Michaelis constant and apparent kinetic parameters were calculated. Importantly, some other blood proteins were less interfering with this system, and it showed reliability in fibrin activity detection in real whole blood samples. This study established a better and more targeted research method of in vitro fibrinolysis and provided dynamic monitoring data for the analysis of fibrinolytic activity of whole blood.

A piezoelectric MEMS microphone with proof mass and its array

Piezoelectric MEMS microphones (PMMs) have attracted increased attention in home automation, wearable devices and autonomous driving, since the high linearity, dustproof and waterproof, and easy manufacturing. In this paper, a hexagonal PMM with proof mass and its array in parallel are proposed using a 20 % Scandium-doped Aluminum Nitride (ScAlN) thin film on a Silicon-on-insulator (SOI) wafer. The theoretical analysis, simulation, fabrication and verification test were discussed. The performance of the devices was simulated using the finite element simulation, and the resonant frequency is 102.85 kHz. The sensitivity of element and its array were measured up to −68.3 dB and −68.4 dB, respectively (re: 1 V/Pa). And the sensitivities of the element and array were −38.6 dB and −37.9 dB at 1 kHz (re: 1 V/Pa) after amplification and filtering. The SNR of the array was increased to 55.3 dB since the increased capacitance of array. Besides, the total harmonic distortion (THD) was measured 1.7 % and 1.14 %, respectively. The PMM and its array with high SNR and good THD is suitable to commercial acoustic fields, especially the high-noise scenarios.