High Linearity Research Articles

Biodegradable poly(lactic acid) blocked polyurethane/carbon nanotubes coated cotton fabric prepared by ultrasonic-assisted inkjet printing for high performance strain sensors

In order to fulfill the demands for degradability, a broad working range, and heightened sensitivity in flexible sensors, biodegradable polyurethane (BTPU) was synthesized and combined with CNTs to produce BTPU/CNTs coated cotton fabric using an ultrasonic-assisted inkjet printing process. The synthesized BTPU displayed a capacity for degradation in a phosphate buffered saline solution, resulting in a weight loss of 25 % after 12 weeks of degradation. The BTPU/CNTs coated cotton fabric sensor achieved an extensive strain sensing range of 0–137.5 %, characterized by high linearity and a notable sensitivity (gauge factor (GF) of 126.8). Notably, it demonstrated a low strain detection limit (1 %), rapid response (within 280 ms), and robust durability, enabling precise monitoring of both large and subtle human body movements such as finger, wrist, neck, and knee bending, as well as swallowing. Moreover, the BTPU/CNTs coated cotton fabric exhibited favorable biocompatibility with human epidermis, enabling potential applications as wearable skin-contact sensors. This work provides insight into the development of degradable and high sensing performance sensors suitable for applications in electronic skins and health monitoring devices.

Quantitative, real-time scintillation imaging for experimental comparison of different dose and dose rate estimations in UHDR proton pencil beams.

Ultra-high dose rate radiotherapy (UHDR-RT) has demonstrated normal tissue sparing capabilities, termed the FLASH effect; however, available dosimetry tools make it challenging to characterize the UHDR beams with sufficiently high concurrent spatial and temporal resolution. Novel dosimeters are needed for safe clinical implementation and improved understanding of the effect ofUHDR-RT. Ultra-fast scintillation imaging has been shown to provide a unique tool for spatio-temporal dosimetry of conventional cyclotron pencil beam scanning (PBS) deliveries, indicating the potential use for characterization of UHDR PBS proton beams. The goal of this work is to introduce this novel concept and demonstrate its capabilities in recording high-resolution dose rate maps at FLASH-capable proton beam currents, as compared to log-based dose rate calculation, internally developed UHDR beam simulation, and a fast point detector (EDGE diode). The light response of a scintillator sheet located at isocenter and irradiated by PBS proton fields (40-210 nA, 250 MeV) was imaged by an ultra-fast iCMOS camera at 4.5-12 kHz sampling frequency. Camera sensor and image intensifier gain were optimized to maximize the dynamic range; the camera acquisition rate was also varied to evaluate the optimal sampling frequency. Large field delivery enabled flat field acquisition for evaluation of system response homogeneity. Image intensity was calibrated to dose with film and the recorded spatio-temporal data was compared to a PPC05 ion chamber, log-based reconstruction, and EDGE diode. Dose and dose rate linearity studies were performed to evaluate agreement under various beam conditions. Calculation of full-field mean and PBS dose rate maps were calculated to highlight the importance of high resolution, full-field information in UHDRstudies. Camera response was linear with dose (R2 = 0.997) and current (R22 = 0.98) in the range from 2-22 Gy and 40-210 nA, respectively, when compared to ion chamber readings. The deviation of total irradiation time calculated with the imaging system from the log file recordings decreased from 0.07% to 0.03% when imaging at 12 kfps versus 4.5 kfps. Planned and delivered spot positions agreed within 0.2 0.1 mm and total irradiation time agreed within 0.2 0.2 ms when compared with the log files, indicating the high concurrent spatial and temporal resolution. For all deliveries, the PBS dose rate measured at the diode location agreed between the imaging and the diode within 3% 2% and with the simulation within 5% 3% CONCLUSIONS: Full-field mapping of dose and dose rate is imperative for complete understanding of UHDR PBS proton dose delivery. The high linearity and various spatiotemporal metric reporting capabilities confirm the continued use of this camera system for UHDR beam characterization, especially for spatially resolved dose rateinformation.

Wearable multichannel-active pressurized pulse sensing platform

With the modernization of traditional Chinese medicine (TCM), creating devices to digitalize aspects of pulse diagnosis has proved to be challenging. The currently available pulse detection devices usually rely on external pressure devices, which are either bulky or poorly integrated, hindering their practical application. In this work, we propose an innovative wearable active pressure three-channel pulse monitoring device based on TCM pulse diagnosis methods. It combines a flexible pressure sensor array, flexible airbag array, active pressure control unit, advanced machine learning approach, and a companion mobile application for human–computer interaction. Due to the high sensitivity (460.1 kPa−1), high linearity (R2 > 0.999) and flexibility of the flexible pressure sensors, the device can accurately simulate finger pressure to collect pulse waves (Cun, Guan, and Chi) at different external pressures on the wrist. In addition, by measuring the change in pulse wave amplitude at different pressures, an individual’s blood pressure status can be successfully predicted. This enables truly wearable, actively pressurized, continuous wireless dynamic monitoring of wrist pulse health. The innovative and integrated design of this pulse monitoring platform could provide a new paradigm for digitizing aspects of TCM and other smart healthcare systems.

Demonstration of temperature monitoring of the curing process in resin transfer moulding using integrated phase-shifted Bragg grating sensors

Composite materials have increased in use across multiple industries due to their low weight, thermal stability and design flexibility. As applications grow, the importance of accurate process-monitoring techniques grows, with various research teams investigating a variety of in situ cure-monitoring sensors. Photonic integrated circuits (PICs) can be a feasible solution in tracking curing cycles due to their resistance to harsh conditions and ease of integration into the production tool. This paper demonstrates the integration and performance evaluation of an embedded phase-shifted Bragg grating solution, instead of commonly used fiber sensors, based on 220 nm height silicon-on-insulator platform for in-situ monitoring of the RTM-6 resin curing process in a composite tool. The embedded optical sensor presents high sensitivity (75 pm/°C) and linearity (R2=0.995) up to 120 °C, enabling precise temperature measurements throughout the curing cycle. The experimental results show consistency with previously reported simulations, throughout the calibration, dry run characterization and the curing process, up to 120 °C, allowing for accurate monitoring of the curing process.

A self-heating gas sensor for online monitoring of endogenous ethylene of post-harvest cut chrysanthemums

The decay of post-harvest cut chrysanthemums (PHCCs) during storage and shipment results in enormous loss, and the accumulated endogenous ethylene is one of the main reasons. However, it is challenging for current technologies to onsite monitoring of endogenous ethylene of PHCCs whose concentration is very low. Here, we propose a ethylene sensor with high performances enabled by self-heating capability. Specifically, laser-induced graphene (LIG) patterns are in-situ fabricated on the upper and lower sides of a polyimide substrate. The upper LIG is coated with chemo-resistive SnO2 for ethylene sensing and the lower LIG serves as heater for self-heating. The working temperature is well tuned by the heater and effectively transferred to SnO2. Owing to the self-heating capability, the sensor displays outstanding ethylene detection performances, such as ultra-low limit of detection (1.654 ppb), wide detection range (0.05–100 ppm), high sensitivity (0.2249 ppm−1), high detection linearity (0.9925), and long-term stability (>14 days). Moreover, the sensor is integrated with a data acquisition circuit and connected to a mobile application, realizing online monitoring of endogenous ethylene of PHCCs. The results demonstrate that the decay of PHCCs is accelerated as the endogenous ethylene accumulates. This work would promote the online monitoring of endogenous ethylene of plants.

The Transfer Function Characterization and Linearization using an Inductive Coupling Circuit for System Measurement in Hard-to-reach Location and in Medical Diagnostics

This research paper demonstrates the scope and potential of a circuit design of the differential sensory system, functional theory and relevant derivations on its operation details when characterizing their transfer function for signal gain. The idea is using inductive coils as transducer elements responding to changes in the parameter being sensed. This phenomenon is the result of simple movement of a core position bringing about proportionate changes in the inductance of the circuit, and hence ultimately in the output parameters. The output parameters include frequency, duty cycle, current, voltage, frequency, frequency hysteresis, speed, acceleration, kinematics, pressure, range of oscillation, angulation, Impedance voltage, Magnetic field strength, and Transfer function. The results shown can be used for characterizing the materials and hence sensor with high sensitivity, linearity and responsiveness in harsh environmental condition is obtained and characterized and their corresponding transfer functions are obtained. This help in sensing broken metallic in the body during war and sensed in hard to reach to reach locations as a result of the huge magnetic field generated. This also, verifies the derivations and the simulation in literature.

Two-dimensional flow vector measurement based on all-fiber laser feedback frequency-shifted multiplexing technology

The decomposition and identification of signals are crucial for flow vector acquisition in a multi-dimensional measurement. Here, we proposed a two-dimensional (2D) flow vector measurement system based on all-fiber laser feedback frequency-shifted multiplexing technology. The reliable performance of the system is characterized by experimental verification and numerical simulation. An orthogonal dual-beam structure is employed to eliminate the impact of an unknown incident angle in the practical application. Meanwhile, the vector velocity signals in 2D can be decomposed into one-dimensional (1D) scalar signals by adopting the frequency-shifted multiplexing, which makes it easy to obtain the vector information and velocity distribution of fluid motion through the self-mixing interference frequency spectrum. Moreover, the measured flow rates present a high linearity with syringe pump speeds ranging from 200 to 2000 μL/min, and the velocity information of the different incidence angles is easily obtained with high precision. This work may pave the way for the acquisition and processing of multi-dimensional flow vector signals, with potential applications in biomedical monitoring and microflow velocity sensing.

Computed chest radiography for total body irradiation: image quality and clinical feasibility

Objective. In myeloablative total body irradiation (TBI), lung shielding blocks are used to reduce the dose to the lungs and hence decrease the risk of radiation pneumonitis. Some centers are still using mega-Volt (MV) imaging with dedicated silver halide-based films during simulation and treatment for lung delineation and position verification. However, the availability of these films has recently become an issue. This study examines the clinical performance of a computed radiography (CR) solution in comparison to radiographic films and potential improvement of image quality by filtering and post-processing. Approach. We compared BaFBrI-based CR plates to radiographic films. First, images of an aluminum block were analyzed to assess filter impact on scatter reduction. Secondly, a dedicated image quality phantom was used to assess signal linearity, signal-to-noise ratio (SNR), contrast and spatial resolution. Ultimately, a clinical performance study involving two impartial observers was conducted on an anthropomorphic chest phantom, employing visual grading analysis (VGA). Various filter materials and positions as well as post-processing were examined, and the workflow between CR and film was compared. Main results. CR images exhibited high SNR and linearity but demonstrated lower spatial and contrast resolution when compared to film. However, filtering improved contrast resolution and SNR, while positioning filters inside the cassette additionally enhanced sharpness. Image processing improved VGA scores, while additional filtering also resulted in higher spine visibility scores. CR shortened TBI simulation by over 10 minutes for one patient, alongside a dose reduction by order of 0.1 Gy. Significance. This study highlights potential advantages of shifting from conventional radiographic film to CR for TBI. Overall, CR with the incorporation of processing and filtering proves to be suitable for TBI chest imaging. When compared to radiographic film, CR offers advantages such as reduced simulation time and dose delivery, re-usability of image plates and digital workflow integration.

Investigation of Retention Mechanism of B2 and B3 in Home-Made ZIC-HILIC Columns and Its Application for The Simultaneous Estimation in Multivitamin Tablets

In the present study, the retention behavior of two vitamins (B2 and B3) was investigated using a zwitterionic hydrophilic interaction liquid chromatography technique (ZIC-HILIC) on two home-made columns, and two analytical methods for these vitamins were established as a result. Several chromatographic parameters were carefully investigated and optimized. The best separation was achieved on two new home-made columns (ZIC-1 and ZIC-3) employing acetonitrile/sodium acetate buffer as the mobile phase (40 mM, pH 4.75). The target vitamins were detected at 254 nm. In the ZIC-1 and ZIC-3 columns, the linear ranges of the target vitamins (B2 and B3) were 0.06-11.0 and 0.08-7.0 µg/mL, respectively. For both target vitamins, the detection and quantitation limits of the suggested methods were 0.011-0.055 and 0.033-0.166 µg/mL, respectively. They also showed high precision (RSD ≤ 0.93), linearity (r2 ≥ 0.9988), and recovery (between 99.0 and 101.71%). The suggested procedures have been validated and tested on multivitamin tablets, proving that they are suitable for analyzing food supplements for these tablets, and acceptable results were obtained for the study.

High‐performance XSBR‐based flexible strain sensors enabled by pleated microcrack structure

AbstractFlexible strain sensors are attracting attention in areas such as medical monitoring sensing and rehabilitation therapy monitoring due to their powerful ability to sense, process, transmit and display complex information. However, it is an urgent challenge to realize the trade‐off between excellent performances such as high sensitivity, high linearity, wide strain sensing range and high durability. Herein, we prepare stretchable conductive composites with wrinkle composite micro‐crack structure by combining carboxystyrene butadiene rubber (XSBR) layer and carboxymethyl cellulose@Ag nanowire‐CNTs (CMC@AgNWs‐CNTs) conductive layer. Based on interfacial interactions, it can be adapted to different needs by adjusting the thickness of the strain sensing layer. When the thickness of the strain sensing layer is 4 μm, the strain sensor has a wide sensing range (strain capacity up to 300%) and high sensitivity (strain sensing factor of 484). At a thickness of 8 μm, the strain sensing performance exhibits a wide strain range, high linear fit and good cyclic stability. This work provides a new research idea to improve the comprehensive performance of flexible strain sensors and the contradiction between wide sensing range, high sensitivity and high linearity.

5‐1: Incell Electromagnetic Resonance Touch LCD with Antenna Coil Integrated in Array Substrate

In this paper, we present an incell integrated electromagnetic resonance(EMR) active pen solution that can form a closed magnetic induction coil without additional panel manufacturing process compared to a regular L CD panel. The Incell EMR touch solution exhibits extremely high accuracy and linearity, such as 0.16mm accuracy and 0.36mm linearity, respectively. Our solution shows significant advantages over capacitive active pen solution especially in slow scribing scenario without any sawtooth phenomenon, achieving a highly intergrated, lightweight, high‐performance, and low‐power consumption solution for handwriting active pen LCD.

Development and validation of an assay to quantify plasma cell-free human papillomavirus DNA for 13 high-risk types that cause 98% of HPV-positive cancers.

6065 Background: Plasma cell-free HPV DNA (cfHPV) may be a valuable tool for identification of patients with local-regionally advanced HPV-positive cancers at risk for recurrence after chemoradiation. Technical validation is required for use as an integral biomarker in a prospective clinical trial. Methods: Cell-Free 13 (i.e., CF13) is a digital-droplet PCR assay for quantification of 13 high-risk HPV types and control ERV3 in plasma that considered both variant sequences into primer/probe design and a distance matrix in phylogenetic analysis in multiplex combinations. Oligonucleotides/plasmids encoding type-specific E6/E7 regions were used as positive controls. Limit of blank, detection, quantification (LoB, LoD, LoQ), linear range, inter- and intra-assay coefficients of variation (CoV), and type-specific cross-reactivity were determined as were sensitivity and specificity for an HPV-positive diagnosis in a cohort of 278 oropharyngeal/unknown primary/oral cavity cancers tested for HPV by E6/E7 mRNA qRT-PCR or p16 IHC and HPV in situ hybridization. Results: Under identical assay conditions, the LoB, LoD and linear range were <1, 5 and 5 to 200,000 virus copies without HPV type-specific cross-reactivity. Multiplexing had no effect on LoD or linearity. LoQ was 16 copies/ml plasma for all 13 HPV types. For 80 and 10,000 copies per ml, inter-assay CoV ranged from ~15-28% and ~3.2-4.6% and intra-assay CoV ranged from ~16-38% and 0.2-3.3%, respectively. cfDNA purification method (manual v automated; extraction efficiency 142% and 91% for 16 and 10,000 HPV16 copies/ml), input plasma volume (1, 2, or 4 ml), total background cfDNA (<1800ng) or genomic DNA (<700ng) did not affect quantification. For a diagnosis of HPV-positive cancer, sensitivity and specificity were 91.1% (214/235) and 97.7% (42/43), respectively. cfHPV was associated with gender, race, T stage, N stage, and primary treatment modality. When compared to below the median (≤230 copies/ml), cfHPV above the median was associated with worse progression-free survival (HR=2.26, 95% CI 1.23-4.17, p=0.009) in univariate analysis. However, this was no longer significant after adjustment for age, T stage, and M stage (HRadj=1.78, 95% CI 0.95-3.35, p=0.07). Conclusions: CF13 has high sensitivity, accuracy, precision, linearity, HPV type-specificity, and robustness, offering a rigorously validated assay applicable to ~98% of patients with HPV-positive cancer. CF13 had excellent clinical sensitivity and specificity for a diagnosis of HPV-positive OPC.

High Power Linearity and Low Leakage Current of AlN/GaN/InGaN Coupling Channel HEMTs With N₂O Oxidation Treatment

High Power Linearity and Low Leakage Current of AlN/GaN/InGaN Coupling Channel HEMTs With N₂O Oxidation Treatment

Printable silicate and RuO2 composite with wide-range linear PTC for high-temperature sensors

3D printing has revolutionised the design and manufacturing of high-temperature thin/thick-film sensors (TFSs). However, existing printable high-temperature materials face cost-performance trade-offs. This study proposes a silicate and RuO2 composite for the 3D printing of TFSs. A silicate compound (SiO2–Al2O3–CaO, SAC) was used as a sintering aid to reduce the sintering temperature of RuO2, forming a silicate glass phase that enhanced film density and substrate adhesion. The SAC also minimised RuO2 particle volatilisation at high temperatures, thus enhancing the stability of the SAC/RuO2 composite. The SAC/RuO2 TFSs demonstrated exceptional performance, with a positive temperature coefficient (502 ppm/°C) from room temperature to 800 °C, high linearity, and stability (resistance drift rate of 0.1 %/h at 800 °C), extending the application temperature of RuO2 by nearly 200 °C from the previous application temperature of 600 °C. Therefore, the SAC/RuO2 composite offers a new low-cost and high-performance solution for using 3D printing technology in harsh environmental sensors such as turbine blades.

Assessing tissue differentiation capabilities in X-ray imaging through cadmium zinc telluride (CZT) photon counting detectors.

In recent years, the use of photon-counting detection technology has resulted in significant X-ray imaging research. This advanced technology holds considerable promise for enhancing Computed Tomography (CT) scanners, offering a potential solution to the limitations inherent in traditional CT detectors. The ongoing studies are dedicated to assessing the effectiveness and sensitivity of semiconductor detector materials in photon counting detectors, particularly in their ability to detect soft tissue contrasts. This study aimed to characterize the performance of the Cadmium Zinc Telluride (CZT) photon counting detector in identifying various tissues with a focus on assessing its sensitivity in distinguishing tissue types in X-ray imaging. An optimal frame rate per second (FPS) of the CZT detector was evaluated by setting the X-ray tube voltage and current at 25 keV and 35 keV and 0.5 mA, 1.0 mA respectively. By keeping the optimum FPS fixed, the detector energy thresholds were set in small steps from 15 keV to 35 keV and the tube currents were set for X-ray tubes in ranges of 0.1 mA–1.0 mA to evaluate the relationship between voltage and current of the X-ray source and counts per second (CPS). The specimens, including fat, liver, muscles, paraffin wax, and contrast media were placed on a stair-step chamber constructed from Plexi-glass, spanning six distinct thickness levels. We investigated X-ray transmission across these tissue samples at varying thicknesses, exploring five energy thresholds: 21 keV, 25 keV, 29 keV, 31 keV, and 45 keV to evaluate their impact on the CPS. This study found that a frame rate of 12 frames per second optimally aligns with the spectral response of the X-ray source. Furthermore, a linear correlation is present between the CPS and the X-ray tube current. The transmission of X-rays through a sample depends on its thickness, a phenomenon observed across different energy thresholds in this study. The detectors exhibit high sensitivity and linearity, ensuring accurate and reliable measurements in diverse imaging scenarios, making them invaluable tools for precise data acquisition in both research and clinical applications.

Impact of eliminating ungated access regions on DC and thermal performance of GaN-based MIS-HEMT

The impacts of eliminating access regions (AR) on DC and thermal performance of GaN-based MIS-HEMT have been studied using a device of 4 µm gate length. Nominal absence of ARs was achieved by a metal-organic chemical vapor deposition-regrown heavily n-doped GaN contact region extended to the two-dimensional electron gas (2DEG) channel (with sheet resistance as low as 14 Ω/ ◻ and ohmic contact resistance of 0.20 Ω⋅ mm) and 22-nm-thick AlN/Al2O3/HfO2 insulator layers acting as both gate dielectrics and sidewall spacers. As a result, a low knee voltage (2.5 V @ VGS = +2 V) comparable to deeply-scaled devices was attained, revealing the dominant role of ARs in knee voltages. High linearity at lower supply voltages (gate voltage swing of 7.3 V @ VDS = 5 V) and a faster GVS saturation trend with V DS increasing were observed, benefiting from the improved utility of applied lateral voltage. Moreover, a much lower thermal resistance compared to that of the conventional MIS-HEMT structure (146 vs. 202 K W−1) was extracted by a static-pulsed I-V measurement method. Simplified TCAD simulations were conducted to explain the underlying mechanisms, demonstrating that the enhanced surface heat flow covered by the gate metal as well as the more uniform electric field along the 2DEG channel accounts for the better capability of heat management in the device free of ARs. Our results indicate the size of DC and thermal performance enhancements obtained by eliminating ARs in a GaN-based MIS-HEMT structure.

Crystallization and Solvent Evaporation Ionization Mass Spectrometry (CSEI-MS) for Rapid Detection of Drugs in Complex Matrices.

Illegal addition of drugs is common but seriously threatens public health safety. Conventional mass spectrometry methods are difficult to realize direct analysis of drugs existing in some complex matrices such as seawater or soil due to the ion suppression effect and contamination to MS parts caused by nonvolatile salts. In this work, a novel crystallization and solvent evaporation ionization mass spectrometry (CSEI-MS) method was constructed and developed to achieve rapid desalting detection. CSEI only consists of a heated plate and a nebulizer and exhibits excellent desalting performance, enabling direct analysis of six drugs dissolved in eight kinds of salt solutions (up to 200 mmol/L) and three complex salty matrices. Under optimized conditions, CSEI-MS presents high sensitivity, accuracy, linearity, and intraday and interday precision. Finally, this method is applied to the quantitative analysis of drugs in seawater, hand cream, and soil. Furthermore, the highly sensitive detection of CSEI-MS is demonstrated to remain even if the detection processes are conducted within 5 s via common commercial tools.

Broad‐range, high‐linearity, and fast‐response pressure sensing enabled by nanomechanical resonators based on 2D non‐layered material: β‐In2S3

AbstractTwo‐dimensional (2D) non‐layered materials, along with their unique surface properties, offer intriguing prospects for sensing applications. Introducing mechanical degrees of freedom is expected to enrich the sensing performances of 2D non‐layered devices, such as high frequency, high tunability, and large dynamic range, which could lead to new types of high performance nanosensors. Here, we demonstrate 2D non‐layered nanomechanical resonant sensors based on β‐In2S3, where the devices exhibit robust nanomechanical vibrations up to the very high frequency (VHF) band. We show that such device can operate as pressure sensor with broad range (from 10−3 Torr to atmospheric pressure), high linearity (with a nonlinearity factor as low as 0.0071), and fast response (with an intrinsic response time less than 1 μs). We further unveil the frequency scaling law in these β‐In2S3 nanomechanical sensors and successfully extract both the Young's modulus and pretension for the crystal. Our work paves the way towards future wafer‐scale design and integrated sensors based on 2D non‐layered materials.image

Piezoresistive and capacitive cement-based stress sensors designed by incorporating carbon nanotubes doped with graphene nanopowder for structural health monitoring

Piezoresistive and capacitive cement-based smart composites are promising candidates for stress monitoring applications in buildings. However, the drawbacks of designing cement-based smart composites with a piezoresistive mechanism sensitive to temperature variations or a capacitive mechanism sensitive to vibration can be solved with sensor designs based on two principles. To address this issue, cement-based smart composites with piezoresistive and capacitive stress sensitivity and significantly improved compressive strength were designed using carbon nanotubes (CNT) doped with graphene nanopowder. A maximum fractional change in electrical resistivity of 90.08% with a high linearity of 98% was obtained with a blend of 0.01 wt%, and the maximum fractional change in capacitance was 163.11% with a high linearity of 97% at 0.05 wt%. Cement-based smart composites have absolute piezoresistive stress sensitivities that vary from 1.38% MPa−1 to 4.16% MPa−1 and 2.54% MPa−1 to 2.57% MPa−1 for blended and impregnated low doses of 0.01 wt% to 0.05 wt% CNT doped with graphene. In addition, capacitive stress sensitivities of 22.74% MPa−1 and 5.1% MPa−1 were achieved by blending and impregnating 0.01 wt% CNT doped with graphene in cementitious composites. Furthermore, the conductive path, overlapping, and tunneling effect created by CNT doped with graphene in cementitious composites and the porous structure in the dielectric layer are responsible for the increased stress sensitivity.

Piezotronic Transistors Based on GaN Wafer for Highly Sensitive Pressure Sensing with High Linearity and High Stability.

Piezotronic effect utilizing strain-induced piezoelectric polarization to achieve interfacial engineering in semiconductor nanodevices exhibits great advantages in applications such as human-machine interfacing, micro/nanoelectromechanical systems, and next-generation sensors and transducers. However, it is a big challenge but highly desired to develop a highly sensitive piezotronic device based on piezoelectric semiconductor wafers and thus to push piezotronics toward wafer-scale applications. Here, we develop a bicrystal barrier-based piezotronic transistor for highly sensitive pressure sensing by p-GaN single-crystal wafers. Its pressure sensitivity can be as high as 19.83 meV/MPa, which is more than 15 times higher than previous bulk-material-based piezotronic transistors and reaches the level of nanomaterial-based piezotronic transistors. Moreover, it can respond to a very small strain of 3.3 × 10-6 to 1.1 × 10-5 with high gauge factors of 1.45 × 105 to 1.38 × 106, which is a very high value among various strain sensors. Additionally, it also exhibits high stability (current stability of 97.32 ± 2.05% and barrier height change stability of 95.85 ± 3.43%) and high linearity (R2 ∼ 0.997 ± 0.002) in pressure sensing. This work proves the possibility of designing a bicrystal barrier as the interface to obtain a strong piezotronic effect and highly sensitive piezotronic devices based on wafers, which contributes to their applications.