High Linearity Research Articles

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.

Fiber Bragg grating-based touch-slip sensor for surface roughness detection

To enable humanoid prosthetic hands to accurately identify and grasp objects, a touch-slip sensor based on fiber Bragg grating (FBG) was proposed in this paper. The sensor was designed with a double-layer sensing structure to detect three-dimensional force, sliding information, surface roughness, and compensate for ambient temperature using a reference grating. To analyze the relationship between the sensor surface structure parameters and FBG's vibration signal, the contact sliding model was introduced. By using a finite element simulation, the contact sliding model was validated, and the surface structure parameters of the sensor were determined. A series of experiments were conducted on the sensor’s three-dimensional force detection, temperature calibration, sliding measurement, and surface roughness detection. Using machine learning methods, a regression prediction model was created. The sensor could detect the surface roughness on the sample plate surface more accurately with a maximum error of 8.58×10−4. This sensor has the following advantages: a simple structure, low cost, high linearity, and quick response time. It provides a new design solution for the detection of touch-slips on humanoid prosthetic hands.

Direct Ink Writing of SiCN/RuO2/TiB2 Composite Ceramic Ink for High-Temperature Thin-Film Sensors.

Direct ink writing (DIW) of high-temperature thin-film sensors holds significant potential for monitoring extreme environments. However, existing high-temperature inks face a trade-off between cost and performance. This study proposes a SiCN/RuO2/TiB2 composite ceramic ink. The added TiB2, after annealing in a high-temperature atmospheric environment, forms B2O3 glass, which synergizes with the SiO2 glass phase formed from the SiCN precursor to effectively encapsulate RuO2 particles. This enhances the film's density and adhesion to the substrate, preventing RuO2 volatilization at high temperatures. Additionally, the high conductivity of TiB2 improves the film's overall conductivity. Test results indicate that the SiCN/RuO2/TiB2 film exhibits high linearity from room temperature to 900 °C, high stability (resistance drift rate of 0.1%/h at 800 °C), and high conductivity (4410 S/m). As a proof of concept, temperature sensors and a heat flux sensor were successfully fabricated on a metallic hemispherical surface. Performance tests in extreme environments using high-power lasers and flame guns verified that the conformal thin-film sensor can accurately measure spherical temperature and heat flux, with a heat flux sensor response time of 53 ms. In conclusion, the SiCN/RuO2/TiB2 composite ceramic ink developed in this study offers a high-performance and cost-effective solution for high-temperature conformal thin-film sensors in extreme environments.

Development of a Polymersome Blood Ammonia Assay Coupled with a Portable Near-Infrared Fluorometer.

Ammonia is a key biomarker in inborn and acquired liver disease. As clinical point-of-care blood ammonia assays are lacking, we developed a polymersome formulation for point-of-care blood ammonia sensing combined with a portable fluorometer. A pH-sensitive near-infrared (NIR) fluorescent dye was identified, which showed a strong fluorescence increase at acidic pH values. Building on reports on ammonia-selective PS-b-PEG polymersomes, these polymersomes were loaded with the NIR dye. These NIR fluorescent polymersomes sensed ammonia in a clinically relevant range in ammonia-spiked fresh whole blood with high linearity (R 2 = 0.9948) after 5 min using a conventional tabletop plate reader. Subsequently, the assay was tested with a portable fluorometer. An ammonia-dependent fluorescence increase was detected in ammonia-spiked fresh mouse blood after 5 min using the portable fluorometer. The NIR dye-loaded PS-b-PEG polymersomes rapidly sensed ammonia with high linearity in whole blood. This assay was successfully combined with a portable fluorometer and only required 3 μL of blood. These findings motivate a further development and clinical translation of this point-of-care blood ammonia assay.

Smart-Adhesive, Breathable and Waterproof Fibrous Electronic Skins.

For the need of direct contact with the skin, electronic skins (E-skins)should not only fulfill electric functions, but also ensure comfort during wearing, including permeability, waterproofness, and easy removal. Herein, the study has developed a self-adhesive, detach-on-demand, breathable, and waterproof E-skin (PDSC) for motion sensing and wearable comfort by electrospinning styrene-isoprene block copolymer rubber with carbon black nanosheets as the sensing layer and liner copolymers of N, N-dimethylacrylamide, n-octadecyl acrylate and lauryl methacrylate as the adhesive layer. The high elasticity and microfiber network structure endow the PDSC with good sensitivity and high linearity for strain sensing. The hydrophobic and crystallizable adhesive layer ensures robust, waterproof, and detaching-on-demand skin adhesion. Meanwhile, the fiber structure enables the PDSC good air and water permeability. The integration of electric and wearable functions endows the PDSC with great potential for motion sensing during human activities as both the sensing and wearable performances.

Comparison and application of the extraction methods for the determination of pharmaceuticals in water and sediment samples

Due to increasing consumption and production, pharmaceuticals are omnipresent in the environment. Regardless of whether they are present in low concentrations, their detection in the environment is of great concern for human health. Due to the appearance of new pharmaceuticals on the market, there is always a need to develop new analytical methods to determine their presence in various environmental samples. So, in this paper, new LC-MS/MS method was developed for the determination of 13 pharmaceuticals (azithromycin, tiamulin, imatinib, febantel, torasemide, omeprazole, linezolid, praziquantel, etodolac, sulfamethazine, sulfafurazole, albendazole, levamisole) in water and sediments samples.Pharmaceuticals were isolated from water by solid-phase (SPE) and stir-bar sorptive extraction (SBSE), while extracts from sediment samples were obtained by matrix-solid phase dispersion (MSPD) and ultrasound-assisted extraction (UAE). After optimization of extraction conditions, the methods were validated in terms of linearity, LOQ, LOD, precision, recovery and matrix effect. The LOQ of the optimized method were 2.5 ng/L-0.5 µg/L for SPE extraction and 0.1–10 µg/L for SBSE extraction from water, and 2.5 ng/g-25 μg/g for MSPD extraction and 0.025 do 5 µg/g for UAE extraction from sediment depending on the pharmaceuticals. Recoveries were matrix dependent (20–150 %), particularly for SBSE extraction and at the lowest investigated concentration tested, so standard addition calibrations were required for quantification in real samples. The standard addition calibration lines showed high linearity (R2 > 0.97) and replicate extractions showed good reproducibility (RSD≤%).Results obtained show that SPE is much more sensitive than SBSE, while for extraction from sediments both methods are equally sensitive, whereas for some tested pharmaceuticals MSPD is better and for others UAE is better. By comparing the sample preparation methods used, attention is drawn to the fact that, despite the large number of possible methods, not all of them are always equally good with regard to the target components and the type of sample.

Ionic liquid-reinforced transparent, stretchable, conductive organic ionic gel with ultra-high sensory capability and ultra-robust impact-resistance

Traditional conductive hydrogels face challenges in environmental stability and mechanical limitations, constraining their applications in wearable devices. Here, we present a novel organic ionic gel by the construction of PVA/EG double polymer network and ionic liquid, named POIG. It showcases outstanding tensile strength (3.01 MPa) and extensibility (820 %). POIG excels in both low and high-speed impacts, dissipating over 90 % of energy in low-speed impacts and outperforming commercial foam five times in high-speed impacts (1.4 kJ/m). The addition of an ionic liquid in POIG creates a stable, uniform, and highly ordered internal conductive structure, leading to ultra-low strain responsiveness (0.2 %), ultra-fast response times (≈10 ms), high linearity (R2 = 0.999), and excellent sensing performance. High stability is also confirmed through 4000 cycles of both tensile and compression testing. Additionally, we developed a real-time sign language recognition system using deep learning, accurately identifying ten gestures with 98.5 % accuracy. This research offers a durable and innovative organic material for future wearable technology and smart devices.

A novel method for ultra-fast determination of phenolics with performance comparable to UPLC/DAD: Method development and validation on analysis of seedless table grapes

Grapes are well-known for the rich content of phenolics with benefits for human health. The reliable identification of phenolics in grapes is essential to explore the related bioactivity, highlighting the value of the grape source. In this work, an ultra-fast method for determining phenolic compounds in HPLC-DAD using a Rapid Resolution High Throughput-RRHT column (RP-C18 4.6 ×50 mm, 1.8 µm) was developed and validated and nine seedless table grapes produced in the São Francisco Valley, Brazil were analyzed. The method showed good sensitivity (LOD≤ 0.65 mg/L and LOQ< 1.12 mg/L), high linearity (R2 > 0.998), selectivity, precision (CV%< 6.82). The recovery (81.5–105.6 %) was adequate for the desired purpose. A total of 41 phenolics were separated in 20 min, rending a resolution equivalent to UPLC-DAD. Thirty-four phenolics were quantified in grapes, including eight phenolic acids, two stilbenes, one phenolic aldehyde, three isoflavones, four flavanols, three proanthocyanidins, five flavonols, and eight anthocyanins. Patented grapes presented a high content of mono glucoside anthocyanins. Brazilian registered grapes presented high anthocyanin content and the presence of 3,5-diglucoside anthocyanins. The validated method is an alternative for rapid identification of phenolics and maybe useful to stablish procedures for identifying compounds in determining the markers in fruit.

Thermoluminescence characteristics of gamma-irradiated Gd:Mg doped silica glass

This study explores the characteristics of thermoluminescence (TL) yield of silica glass doped with Gd2O3 and MgO for dosimetry via sol-gel route, with varying concentrations of rare earth metal oxides, ranging from 0.1 to 0.8 mol%. Gamma irradiation was delivered using 1.25 MeV 60Co, with entrance doses of 2–10 Gy. The characterization of Gd:Mg-doped SiO2 included assessing TL dose response, sensitivity, linearity index, glow curve, and fading. It has been found that 0.2 mol% Gd:Mg-doped SiO2 shows promising TL dosimetric properties due to its high linearity, high sensitivity, and low thermal fading. In addition, it demonstrated exceptional dosimetric response across the entire dose range studied, with a coefficient of determination R2 exceeding 91%. A computerized glow curve deconvolution method was conducted to determine the kinetic parameters by using Glowfit software. The glow curves include five peaks associated with activation energies and frequency factors with values 0.88–2.42 eV and 5.58 × 106–7.22 × 1026 s−1, respectively. The 0.2 mol% Gd:Mg-doped SiO2 demonstrates minimal fading effects, retaining a significant portion of the TL signal with ∼33% of the initial signal lost over 28 days post-irradiation. The results indicate that the Gd:Mg-doped SiO2 offers a promising performance as a low-cost passive radiation dosimeters.

Construction of polyimide films with highly linear structures using a structural reorganization approach

AbstractTo improve the thermodynamic and mechanical properties of asymmetric polyimide (PI), a method to enhance the linearity of PI by using a structural reorganization approach was designed. First, two novel diamines containing benzimidazole and benzoxazole groups, namely PADBZ and PDBOA, were constructed and synthesized. Thereafter, two new kinds of PI films (PADBZ‐PMDA and PDBOA‐PMDA) were prepared and polymerized with 1,2,4,5‐benzenetetracarboxylic anhydride (PMDA). Based on structural reorganization, PADBZ‐PMDA and PDBOA‐PMDA had repeating units of the same chemical composition and different linearity with PABZ‐BPDA and BOA‐BPDA, respectively. Comparing PADBZ‐PMDA and PABZ‐BPDA, due to the transfer in the position of benzene, PADBZ‐PMDA with high linearity showed the improved heat resistance (Tg up to 448°C), dimensional stability (CTE down to 2.3 ppm/K) and mechanical properties. PDBOA‐PMDA and BOA‐BPDA had the same situation. This study provided a unique solution to enhance the performances of PI by increasing the linearity using a structural reorganization approach.

Relative intensity noise reduction for noise-like pulses based on synchronous intensity modulation

Extra-cavity synchronous intensity modulation is a straightforward and effective approach to suppress the full-bandwidth relative intensity noise (RIN) for noise-like pulse (NLP) fiber lasers. In this work, the picosecond NLPs are produced by a homemade Er/Yb co-doped mode-locked fiber laser and subsequent optimized by the synchronous intensity modulation device. The photodetector (PD) and electro-optical modulator (EOM) allow the real-time measurement and modulation for each optical pulse. A detailed description of key parameters for components is presented. The impact of DC bias voltage and RF signal amplitude on resulting RIN is experimentally investigated. We demonstrate a noteworthy reduction in RIN from 5.62% before synchronous intensity modulation to 1.91% afterward. Numerical investigations suggest that this method is potential to suppress RIN to below 1% under ideal conditions. The key factor in RIN reduction is correct operating region and high photoelectric-conversion linearity. The synchronous intensity modulation is an effective method to obtain low-RIN NLP laser sources, valuable for some practical applications.

Precision Temperature Measurement and Error Analysis for Three-Wire PT100 Resistance Temperature Detector (RTD) using LTSpice

This work focuses on temperature measurement and error extraction for Resistance Temperature Dependence (RTD). RTD is notable for its high accuracy, linearity, and stability. However, obtaining a system error of less than unity in RTD is critical. A platinum RTD is an ideal option if the system requires an accuracy level over a wide temperature range (-200°C to +800°C). Therefore, this work investigated the temperature measurement and extraction of error in RTD by simulating a three-wired PT100 RTD using LTSpice. The analytical calculations were also developed to demonstrate the RTD’s error and were compared with the simulation results for verification purposes. It was discovered that the optimized temperature measurement and percentage errors are 0.01°C and 0.004% respectively. The values of Vc, Sense Resistor (RSENSE), and Reference Resistor (RREF) for the excitation current were found to be significant to maximize the output voltage and mean absolute error (MAE) on the test set, offering insights into the model's overall fit, average deviation, and sensitivity to outliers. Results reveal strong correlations between PV module temperature, irradiance, and AC power generated.

A Compact, Low-Power, and Low-Jitter Fractional-N Phase-Locked Loop with a Single-Ended Ring Voltage-Controlled Oscillator in a 12 nm CMOS FinFET

PLLs with small areas, low power consumption, and low jitter are crucial for mobile applications. Hence, achieving a balance between the area, power consumption, and noise of a PLL is a significant issue. In this work, a compact, low-power, and low-jitter fractional-N PLL using Ring-VCO is introduced. In order to reduce area and power consumption, a single-ended Ring-VCO is implemented. Additionally, novel resistance matrixes are proposed to decrease phase noise. The resistor matrix creates 13 frequency tuning curves with close VCO gain and different initial frequencies, reducing the VCO gain and thus the overall noise while maintaining high tuning linearity. The proposed PLL is fabricated based on 12 nm FinFET technology with a 0.078 mm2 area. It achieves a 2.702 ps RMS jitter at 5.76 GHz while consuming 6.4 mW. Moreover, it maintains a low power consumption and a low RMS jitter across the entire frequency range.

Determination of 16 ultraviolet–absorbing compounds in marine invertebrates by using LC-USI-MS/MS coupled with QuEChERS

In this study, we examined multiple endocrine-disrupting ultraviolet-absorbing compounds (UVACs) in marine invertebrates used in personal care products and packaging. Modified QuEChERS and liquid chromatography UniSpray ionization tandem mass spectrometry were used to identify 16 UVACs in marine invertebrates. Matrix-matched calibration curves revealed high linearity (r ≥ 0.9929), with limits of detection and quantification of 0.006–1.000 and 0.020–3.000 ng/g w.w., respectively. In oysters, intraday and interday analyses revealed acceptable accuracy (93%–120%) and precision (≤18%), except for benzophenone (BP) and ethylhexyl 4-(dimethylamino) benzoate. Analysis of 100 marine invertebrate samples revealed detection frequencies of 100%, 98%, 89%, 64%, and 100% for BP, 4-hydroxybenzophenone, 4-methylbenzophenone, 4-methylbenzylidene camphor, and benzophenone-3 (BP-3), respectively. BP and BP-3 were detected at concentrations of 4.40–27.39 and < 0.020–0.560 ng/g w.w., respectively, indicating their widespread presence. Overall, our proposed method successfully detected UVACs in marine invertebrates, raising concerns regarding their potential environmental and health effects.

Batch Fabrication of Flexible Strain Sensors with High Linearity and Low Hysteresis for Health Monitoring and Motion Detection.

In recent years, flexible strain sensors have gradually come into our lives due to their superiority in the field of biomonitoring. However, these sensors still suffer from poor durability, high hysteresis, and difficulty in calibration, resulting in great hindrance of practical application. Herein, starting with interfacial interaction regulation and structure-induced cracking, flexible strain sensors with high performance are successfully fabricated. In this strategy, dopamine treatment is used to enhance the bonding between flexible substrates and carbon nanotubes (CNT). The combination within the conductive networks is then controlled by substituting the CNT type. Braid-like fibers are employed to achieve controllable expansion of the conductive layer cracks. Finally, we obtain strain sensors that possess high linearity (R2 = 0.997) with low hysteresis (5%), high sensitivity (GF = 60) and wide sensing range (0-50%), short response time (62 ms), outstanding stability, and repeatability (>10,000 cycles). Flexible strain sensors with all performances good are rarely reported. Static and dynamic respiration and pulse signal monitoring by the fiber sensor are demonstrated. Moreover, a knee joint monitoring system is constructed for the monitoring of various walking stances, which is of great value to the diagnosis and rehabilitation of many diseases.

High linearity AlGaN/GaN HEMTs with Au-free Ti/Al/Ni/Ti ohmic contacts for Ka-band applications

In this study, AlGaN/GaN HEMTs with Au-free Ti/Al/Ni/Ti ohmic contacts were fabricated. The device presents a contact resistance (R c) of 0.64 Ω·mm and high linearity characteristics. The two-tone measurement at 28 GHz shows that the 2 × 50 μm device exhibits an excellent third-order intercept point (OIP3) value of 41.64 dBm at V DS = 28 V, and an OIP3/P DC of 24.2. An OIP3 of 46.59 dBm was achieved when the device’s gate width was increased to 8 × 50 μm at V DS = 48 V. These results demonstrate that AlGaN/GaN HEMTs with Ti/Al/Ni/Ti ohmic contacts have potential for Ka-band applications.

An instrumentation amplifier with series switch pseudo resistor DC-servo loop realizing 0.16-Hz high-pass corner

This paper presents an instrumentation amplifier for electrocardiogram (ECG) signal recording. A DC servo loop (DSL) based on a series-switch pseudo resistor (S2PR ) is utilized to suppress the effect of the unavoidable electrode DC offset effectively. The two-step pulse generation circuit realizes two sets of pulse signals with shallow duty cycles, and the pulse signals drive the path switches and virtual switches in the S2PR, respectively. Virtual switches reduce the channel charge injection effect, and finally, a great equivalent resistance with high linearity is realized. The continuous DSL realized based on S2PR can suppress the electrode DC offset of ±180 mV. At the same time, the active area of the DSL is significantly reduced. The proposed instrumentation amplifier is realized in a standard 0.18-μm CMOS process. Simulation results show the DSL designed with a 1.8-V supply introduces a 0.16-Hz high-pass corner. The power consumption of the S2PR-DSL is 92.7 μW. The gain of the instrumentation amplifier is 39.8 dB, and the input-referred noise at the TT corner is 1.78 μVrms over a bandwidth of 0.5 Hz to 150 Hz. The input impedance of the instrumentation amplifier is 772.2 MΩ, when the input signal frequency is 50 Hz, and the total harmonic distortion (THD) of a 10-mVpp input sinusoidal signal at 9.033 Hz is −61.6 dB.

Optical-Electrical Coordinately Modulated Memristor Based on 2D Ferroelectric RP Perovskite for Artificial Vision Applications.

Traditional artificial vision systems built using separate sensing, computing, and storage units have problems with high power consumption and latency caused by frequent data transmission between functional units. An effective approach is to transfer some memory and computing tasks to the sensor, enabling the simultaneous perception-storage-processing of light signals. Here, an optical-electrical coordinately modulated memristor is proposed, which controls the conductivity by means of polarization of the 2D ferroelectric Ruddlesden-Popper perovskite film at room temperature. The residual polarization shows no significant decay after 109-cycle polarization reversals, indicating that the device has high durability. By adjusting the pulse parameters, the device can simulate the bio-synaptic long/short-term plasticity, which enables the control of conductivity with a high linearity of ≈0.997. Based on the device, a two-layer feedforward neural network is built to recognize handwritten digits, and the recognition accuracy is as high as 97.150%. Meanwhile, building optical-electrical reserve pool system can improve 14.550% for face recognition accuracy, further demonstrating its potential for the field of neural morphological visual systems, with high density and low energy loss.

Fiber optic Fabry–Pérot salinity sensor based multiple conductive hydrogel sensing layers

This study introduces a new type of salinity sensor based on fiber optic Fabry-Pérot (FOFPS) featuring a tip coated with intelligent chemical cross-linked network materials. The sensor integrates a single-mode optical fiber, capillary tube, and quartz rod, bonding both ends using UV glue. Furthermore, it employs a multi-layer coating of polyacrylic acid (PAA)-polyacrylamide (PAAm) hydrogel achieved through layer-by-layer stacking technology. Results indicate the FOFPS's capability to measure salinity in aqueous. Across concentrations ranging from 0 ‰ to 45 ‰, a linear correlation between wavelength and concentration is observed. FOFPS utilizing PAA-PAAm hydrogel exhibits a sensitivity of approximately 1.241 nm/‰, high linearity of 0.995, and maximum drift of 57.971 nm. These findings underscore the efficacy of PAA-PAAm hydrogel as a sensing layer in FOFPS, highlighting its superior adjustability, responsiveness, linearity, and suitability for environmental refractive index sensing applications.

Use of a sample injection loop for an accurate measurement of particle number concentration by flow cytometry

Flow cytometry plays a pivotal role in biotechnology by providing quantitative measurements for a wide range of applications. Nonetheless, achieving precise particle quantification, particularly without relying on counting beads, remains a challenge. In this study, we introduce a novel exhaustive counting method featuring a sample loop–based injection system that delivers a defined sample volume to a detection system to enhance quantification in flow cytometry. We systematically assess the performance characteristics of this system with micron-sized polystyrene beads, addressing issues related to sample introduction, adsorption, and volume measurement. Results underscore the excellent analytical performance of the proposed method, characterized by high linearity and repeatability. We compare our approach to counting bead–based measurements, and while an approximate bias value was observed, the measured values were found to be similar between the methods, demonstrating its comparability and reliability. This method holds great promise for improving the accuracy and precision of particle quantification in flow cytometry, with implications for various fields including healthcare and environmental monitoring.