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As the technology is scaled-down and with a decrease in oxide thickness, the effect of NBTI is a major reliability issue in semiconductor industries. NBTI is an aging phenomenon in which the PMOS transistor degraded over time. Deviation in the threshold voltage of PMOS transistor results from NBTI with stress time which affects various parameter of SRAM memory such as degradation in drain current, RSNM, HSNM and access time. NBTI induced aging effect on 6 T and 8 T SRAM cell have been analyzed in this paper for the stress time of 10 years. The reliability parameters of 6 T SRAM cell obtained from simulation result shows there is 6.53%, 23.86%, 3.36% and 13.42% change in Hold SNM (HSNM), Read SNM (RSNM), Write margin and standby leakage current respectively after 10 years. Similarly in 8 T SRAM cell HSNM, RSNM, Write margin and leakage current changes by 5.81%, 5.01%, 3.11%, and 13.24% respectively. This paper also presents the leakage current sensing technique based NBTI monitoring sensor using NMOS transistors only. The sensitivity of the sensor is 40 µV/nA and the linearity of the sensor is upto the practical leakage current range of SRAM cell. Thus we can conclude that the proposed sensor works fine with greater linearity and sensitivity.

In this work, we demonstrate the realization of L-Shaped Schottky Barrier FET as a biosensing device with improved sensitivity. The proposed device uses dual material gate with work functions of 4.2 eV (Al) and 4.8 eV (Cu) and Hafnium Oxide (HfO2) as the gate dielectric. In order to detect the biomolecule, a nano-gap cavity is created in the vertical gate (Gate1) by etching out the oxide. The electrical characteristics of biomolecules such as dielectric constant and charge density modulate the Schottky Barrier width, which in turn, changes the drive current of the device. Various sensitivity parameters have been thoroughly investigated at VDS = VGS = 0.5V and a comparative analysis with the conventional device has been performed. The results so obtained reveal that ION sensitivity of the proposed device is much better for both neutral as well as charged biomolecules (maximum of 21x for neutral, at K=12; 20x for charged biomolecules at ρ=-5x1010cm-2, at K=12). Besides this, the ION/IOFF sensitivity, transconductance (gm) sensitivity and selectivity show similar improvements. Further, the proposed device shows better sensitivity performance at low as well as at higher temperatures as compared to the state-of-the-art biosensing devices.

Bushing plays a significant role in insulation and mechanical support for power transformers. Its working state is closely related to the reliable operation of power transformers. To overcome the electromagnetic interference and security risks during sensor installation, a Sagnac interference optical technique for partial discharge (PD) detection is proposed in this paper. By establishing a simulation model of the sensing structure, it is verified that output signal amplitude varies periodically with the length of sensing and delay fibers. Moreover, the output value decreases with increasing probe radius. The results show that a delay fiber of 1.5 km, a sensing fiber of 3 m, and a bending radius of 5 mm are optimal parameter combinations to detect PD in a 72.5 kV defective bushing. In addition, consistent detection waveforms induced by both internal and external defects are obtained by the optical sensor and high frequency current transformer (HFCT) simultaneously, then the effectiveness of the optical sensor on detecting PD signals for bushing is verified. It is of great help to carry out online monitoring of bushing insulation defects through optical non-destructive installation.

This paper presents a fully RF-powered wireless transceiver integrating an efficient RF energy harvester (RFEH), a wake-up receiver (WuRx), and a wake-up transmitter (WuTx) on a single CMOS chip. The WuRx is designed to operate with supply voltages as low as 300 mV allowing to be entirely powered up by the RF energy at power levels as low as -26 dBm. The capability of the WuRx to operate without using a power management unit (PMU) enhances the sensitivity and overall conversion efficiency of RFEH system. By utilizing an ultra-low-power ultra-low-voltage envelope detector to obtain the required signal levels, using passive amplification instead of an active low-noise amplifier, and eliminating the voltage regulator removing its power overhead, the transceiver’s input sensitivity has been improved at least by a factor 2 (3 dB) compared to the other previously reported RF-powered transceivers.. The proposed transmitter consists of a fast start-up oscillator and an efficient class E power amplifier, which can be externally tuned for different output powers. Fabricated in TSMC’s 130 nm CMOS process, the measurement results show that the proposed WuRx consuming only 5.7 nW works with input powers as low as -26 dBm, and the proposed transmitter can work with input powers as low as -23 dBm. The WuTx outputs -11 dBm with 51% efficiency at 2.45 GHz using high-Q off-chip components.

A passive field conversion-amplification scheme, is proposed and demonstrated for the first time, by integrating a magnetic cantilever with a TMR (Tunnel magnetoresistance) for current monitoring. In the scheme, a magnetic structure with a strong field, is driven and vibrated by the interaction with a weak field. The passive movement of magnetic structure physically results in a movement of strong field. The weak field, is converted by the movement and further passively amplified into a strong one. The degree of amplification is determined by the structure geometry, the position of magnetic structure, as well as the weak field. A TMR cantilever current sensor, mainly composed of two units, is developed to demonstrate the proposed scheme. One is a cantilever with a permanent magnet fixed at its free end as a sensing unit and the other is the TMR as a detecting unit. Experimental measurements demonstrate that a higher detection sensitivity can be achieved, compared to that with only TMR detection. The gain of the sensitivity reaches more than an order of magnitude. If an energy harvesting unit is integrated into the current sensor, a self-powered sensing node can be accomplished for potential wireless sensor network (WSN) applications.

Multi-element array photoelectric detector is the core devices to form a photoelectric detection target with a large field of view. This photoelectric detection target brings about the problem of uneven detection sensitivity distribution in the detection screen. To improve the uneven detection sensitivity of this photoelectric detection target, this paper analyzes the distribution law of the uneven detection sensitivity of the photoelectric detection target using the multi-element array photoelectric detector, dissects the main factors affecting the detection sensitivity according to the photoelectric detection principle, establishes the calculation model of detection sensitivity of the photoelectric detection target in the different detection areas and proposes a method to improve the detection sensitivity by compensating the gain of each unit photoelectric detector. The analysis of simulation and experimental results show that the proposed method of photoelectric detection target can effectively improve the output signal amplitude of the projectile under the certain detection distance, in particular, the output signal amplitude of the projectile is significantly increased when the projectile passes through the detection blind area. The experimental results are consistent with the simulation results, which verify the effectiveness of the proposed improvement method.

A unidirectional microelectromechanical system (MEMS) microphone single module for handsfree and voice recognition systems in automobiles is presented. Because in-cabin noise and temperature variation affect the reduction in the handsfree and voice recognition system performance, noise suppression and increasing the signal-to-noise ratio (SNR) of the microphone are required. In this study, a capacitive MEMS microphone module with a high SNR and a unidirectional characteristic is achieved by designing the structure, package, and module of the MEMS microphone. To improve the SNR, the microphone is developed using a slit-edged membrane. The slit structure is designed to release the residual stress of the membrane to achieve improved sensitivity and SNR. The unidirectional characteristic of the microphone enables suppression of noise signals from undesired directions. The directional characteristic of the microphone is realized by attaching a porous SU-8 filter to delay the time to one of the two acoustic ports on the package. Tests on the proposed unidirectional MEMS microphone package and module show that an SNR of 62.4 dB and a front-back ratio of 27.1 dB are achieved.

In this paper, we present the first CMOS SPAD with performance comparable or better than that of the best custom SPADs, to date. The SPAD-based design, fully integrated in 180 nm CMOS technology, achieves a peak PDP of 55% at 480nm with a very broad spectrum spanning from NUV to NIF and a normalized DCR of 0.2cps/m2, both at 6V of excess bias. Thanks to a dedicated CMOS pixel circuit front-end, an afterpulsing probability of about 0.1% at a dead time of3ns were achieved. We designed three SPADs with a diameter of 25, 50, and 100m to study the impact of size on the timing jitter and to create a scaling law for SPADs. For these SPADs, a SPTR of 12.1ps, 16ps, and 27ps was achieved at 6V of excess bias, respectively. The SPADs operate in a wide range of temperatures, from -65C to 40C, reaching a normalized DCR of 1.6 mcps/m2 at 6V of excess bias. The proposed SPADs are ideal for a wide range of applications, including LiDAR, super-resolution microscopy, QRNGs, QKD, fluorescence lifetime imaging, time-resolved Raman spectroscopy, to name a few.

This paper presents a cost-effective, ultra-low-power and highly sensitive wake-up receiver (WuRX) to reduce overall power consumption of Wireless Sensor Networks (WSN). The proposed tuned radio frequency (TRF) receiver (RX) analogue front-end (AFE) incorporates a 400-MHz, low-power, low-noise amplifier (LNA) with a high voltage gain of 50 dB as well as a Gilbert Cell based envelop detector achieving a conversion gain of 224 V-1 to enhance the overall sensitivity of the WuRX. Meanwhile, a duty-cycling technique is used to reduce the power consumption of the WuRX AFE. In addition, a 31-bit correlator is implemented in the WuRX digital back-end (DBE) to further improve the sensitivity of the WuRX by 4 dB. A proof-of-concept WuRX circuit prototype has been fabricated in a low-cost 180-nm CMOS technology. Measurement results show the complete WuRX attains a sensitivity of -84.5 dBm at a wake-up error rate (WER) of 10-3 whilst only consuming 193 nW at the minimum data rate of 64 bps with a carrier frequency of 402 MHz. With the sensitivity unchanged, the data rate of the WuRX can be scaled up from 64 bps to 8.2 kbps. The used 4-time oversampling technique makes the WuRX robust against asynchronization and clock deviation between the TX and RX. The proposed WuRX is a promising solution for energy-efficient rendezvous between wireless sensor nodes, particularly in application scenarios where both low power consumption and high sensitivity are indispensable.

Remote non-contact monitoring of human vital signs has recently received lots of attention due to the advancement and availability of millimeter wave (mmWave) radars. These sensors are significantly reduced in size, but still face serious electromagnetic (EM) propagation loss and signal obstructions resulting in lower signal-to-noise ratios (SNR). As mmWave received signals also have higher sensitivity to body motions, these effects typically degrade the accuracy of heart rate (HR) detection. To overcome this challenge, MIMO configuration can be used to improve the SNR level by taking advantage of its channel diversity. We use here a Frequency Modulated Continuous Wave (FMCW) radar from Texas Instruments (TI) at 77 GHz to collect data from 192 channels. Additionally, vital sign information is extracted using Arctangent Demodulation (AD) and Maximal Ratio Combining (MRC) combined with an adapted-wavelet Continuous Wavelet Transform (CWT) are utilized to demonstrate improvement of HR estimation accuracy.

Commercial coherent receivers utilize balanced photodetectors (PDs) with high single-port rejection ratio (SPRR) to mitigate the signal-signal beat interference (SSBI) due to the square-law detection process. As the symbol rates of coherent transponders are increased to 100 Gbaud and beyond, maintaining a high SPRR in a cost-effective manner becomes more and more challenging. One potential approach for solving this problem is to leverage the concept of single-ended coherent receiver (SER) where single-ended PDs are used instead of the balanced PDs. In this case, the resulting SSBI should be mitigated in the digital domain. In this paper, we show that SSBI can be effectively mitigated using various low-complexity techniques, such as the direct filed reconstruction (DFR), clipped iterative SSBI cancellation (CIC) and gradient decent (GD). In addition, we present a self-calibration technique for SERs which can be extended for characterizing the optical-to-electrical (O/E) response of a conventional balanced coherent receiver (BR). Using the developed techniques, we then experimentally demonstrate a 90 Gbaud probabilistically constellation shaped 64-QAM (PCS-64QAM) transmission using a SER, achieving a net data rate of 882 Gb/s over 100 km of standard single mode fiber (SSMF). The sensitivity penalty compared to the BR is below 0.5 dB. We expect that when the symbol rate is increased further, a SER can potentially outperform a BR, especially when applied to cost-sensitive commercial pluggable coherent transceivers

Electronic skins are artificial skin-type multifunctional sensors, which hold great potentials in intelligent robotics, limb prostheses and human health monitoring. However, it is a great challenge to independently and accurately read various physical signals without power supplies. Here, a self-powered flexible temperature-pressure bimodal sensor based on high-performance thermoelectric films and porous microconed conductive elastic materials is presented. Through introducing flexible heat-sink design and harvesting body heat energy, the thin-film thermoelectric device could not only precisely sense temperature signal but also drive the pressure sensor for detecting external tactile stimulus. The integration of Bi-Te based thermoelectric film with high stability in wide temperature range enables the sensor to sense the ambient temperature with high resolution (

Modified/controlled atmosphere applications, as an alternative to the chemical treatments, are an effective technique in controlling pest of stored products, especially dried fruits. In gas tight units, it is applied with the principle of preventing the insect respiration by changing the oxygen (O2), carbon dioxide (CO2) and nitrogen (N2) gas levels of the atmosphere. In the study, 1-, 2- and 3- d-old pupae of dried fruit beetle, Carpophilus hemipterus (L.), which is an important dried fruit pest, were exposed to the modified / controlled atmosphere. The modified/controlled atmosphere consisting of 2.1% O2 + 90% CO2 + 7.9% N2 gas mixture was applied for 48, 72, 96 and 120 h at 20°C and 75 ± 5% relative humidity. One, two and three d old pupae responded similarly to modified/controlled atmosphere application. Mortality rates remained close in each exposure time and no significant difference was found between age groups. Unlike the age factor, the exposure time was found to be statistically significant and the mortality rates increased as the exposure time increased in each age group. The highest mortality rates were found as 38, 60 and 47% in 1-, 2- and 3-d old pupae after 120 h of application, respectively.

This paper proposes a novel ultra-low power, tunable, and asynchronous baseband architecture for joint radio frequency (RF) wake-up and charging receivers. The designed system switches between the wake-up and charging operations based on the type of the received RF signal. To our knowledge, the proposed system is the first of a kind that introduces multiple power states to reduce the energy consumption by sequentially activating minimal components required for RF wake-up or charging. The fabricated prototype, using off-the-shelf components, features a sensitivity of -40 dBm, a bit rate of 500 bps, and a current consumption of 225 nA at a bias voltage of 2.6 V in the listening state. Current consumption is estimated at 3.225 μA and 13.725 μA while processing the preamble and bit sequence, respectively. The address detector is powered OFF during charging to reduce the system’s current consumption to 150 nA. Our experimental results show that shutting down the address detector during charging reduces charging time and allows charging from received power levels that are as low as -6 dBm. We demonstrate that, operating the detector with multiple power modes reduces its current consumption and enhances its noise immunity when compared to conventional address detectors with two power modes of operation.

Detecting defects in high-permeability steel components can be challenging when using the eddy current technique. This is due to the strong magnetization signal that is simultaneously generated along with the eddy current signal. To minimize the regions of the induced eddy current and its detection, an eddy current probe based on an array of miniature fluxgate sensors (DRV425, Texas Instrument, USA) and axial inductors was proposed and fabricated in the study. The fluxgate sensors were arranged in two layers, and the sensors were sandwiched between two layers of inductors. The output signals from the fluxgate array were sampled to obtain a differential signal of the eddy current intensity and direction. A phase-sensitive detection technique was implemented to isolate the strong magnetization signal from the detected eddy current signal and utilized to characterize artificial slits with varying depths. The developed probe successfully characterized both the vertically and horizontally oriented slits with depths from 2 to 10 mm on a 12 mm thick mild steel plate. A better sensitivity was notable in the evaluation of the vertical slits where the vertical slits would increase the eddy current intensity in contrast to the horizontal slits around the slits. It was shown that the eddy current’s distribution map obtained from the developed probe could be used to reveal the physical dimension of the slit.

An optical fiber sensor is proposed and experimentally demonstrated for simultaneous measurement of high temperature and transverse load. The sensor is designed by splicing a silica capillary tube (SCT) to a single-mode fiber (SMF) and then heating the SCT to form an air bubble. SCT simultaneously functions as a Fabry Perot (F-P) microcavity and an anti-resonant reflection waveguide. These sensing mechanisms lead to high contrast sensitivity values of temperature and transverse load (1.89pm/°C,190.48pm/N and 24.93pm/°C, 16.68pm/N). Remarkably, the temperature sensitivity of this sensor is eleven times higher than that of the current fiber-tip micro-cavity (2.1 pm/°C). The sensor is also more advantageous in quantitative production and practical application due to its low cost, ease of fabrication, good mechanical strength, and convenient reflection probe.

N400 is an objective electrophysiological index in semantic processing for brain. This study focuses on the sensitivity of N400 effect during speech comprehension under the uni- and bi-modality conditions. Varying the Signal-to-Noise Ratio (SNR) of speech signal under the conditions of Audio-only (A), Visual-only (V, i.e., lip-reading), and Audio-Visual (AV), the semantic priming paradigm is used to evoke N400 effect and measure the speech recognition rate. For the conditions A and high SNR AV, the N400 amplitudes in the central region are larger; for the conditions of V and low SNR AV, the N400 amplitudes in the left-frontal region are larger. The N400 amplitudes of frontal and central regions under the conditions of A, AV, and V are consistent with speech recognition rate of behavioral results. These results indicate that audio-cognition is better than visual-cognition at high SNR, and visual-cognition is better than audio-cognition at low SNR.

This paper introduces a new burst-mode coherent receiver configuration that drastically widens the receiver input dynamic range. Its key advance is a fast feed forward gain control scheme for both a semiconductor optical amplifier (SOA) used as a preamplifier and trans-impedance amplifiers (TIAs) set at the coherent receiver. The two-stage optical and electrical gain control greatly decreases the received burst signals power variations and increases the receiver dynamic range which attenuates the quantization errors in analogue-to-digital conversion (ADC). To elucidate the receiver sensitivity characteristics, bit error rate (BER) calculations are conducted on 10 Gbit/s single polarization quadrature phase shift keying (SP-QPSK) signal coherent reception. The calculations focus on two significant parameters that greatly impact the quantization noise; ADC vertical resolution and received signals state of polarization (SOP). The calculation results confirm that the proposed configuration achieves high sensitivity, better than -44 dBm, and wide dynamic range of 30 dB in the worst SOP condition, even when 5-bit ADC is used. Transmission experiments verify the calculated sensitivities and extremely high loss budget of 48.6 dB is achieved in 40-km single mode fiber (SMF) transmission. These results show that the proposal has the potential to realize 10 Gbit/s class long-reach and high splitting ratio PONs; the extremely wide dynamic range yields 40 km reach PON systems with 512- or 1024-way splits with no change in receiver configuration.

We demonstrate a novel low power inductive wearable plethysmography system. This consists of ultra-sensitive 3D knitted helical coils integrated in a garment and an oscillator circuit with high quality factor. The low power oscillator is built using two cross coupled FET pairs with low capacitance drawing only 95 μA during operation and with a response time smaller than 10 μs . The sensor system is linear, with negligible hysteresis. The best compromise in sensitivity and power consumption is obtained with a 3D knitted helical coil using jersey knit with elastic yarn, a lower knitting needle size than recommended for the yarn and minimizing both the number of stitches per winding as well as the stitches containing metal. A sensitivity of 2.7 kHz per mm change in circumference with a power consumption of 6.85 mW per 30 ms measurement time is reported. This system can be used for long term breathing monitoring using a garment indistinguishable from everyday clothing.

A highly sensitive, large throughput and wide dynamic range (in the aspect of size and material type) broadband tunable microwave interferometer based rectangular waveguide wear debris detection system is presented. Passing of (non)ferrous and (non)conductive particles through the sensor, which causes inductance and/or capacitance changes, are detected as transmission signal variations of the system. We first demonstrate the sensing principle with the aluminum particle of 800 μm and epoxy resin particle of 1 mm3 at 6 GHz. Then, the effects of particle size and flow speed are tested with aluminum particles ranging from 200 μm to 1.8 mm. The measurement results show that the system is able to measure particle sizes with known material and differentiate nonconductive particles from conductive ones. With the proposed data processing techniques, this system is capable of detecting as small as 76 μm particles within an 8 mm outer diameter tube. And with future improvements on sensitivity and particle material characterization, the proposed system has the potential to differentiate (non)ferrous and (non)conductive particles and measure their sizes as a real-time wear debris sensing devices for rotating and reciprocating machines.

The Ga2O3/(0,0.25,0.5,0.75, and 1) CdO thin films have been deposited using PLD technique onto quartz substrates at 300 °C and subsequently annealed in air at temperatures 750 °C for 5 h. The films have been tested for NH3 and NO2 sensing at various operating temperatures. The films showed fast response speed for NO2 gas (10.8 s) for 75% wt sample at 250 °C and (9 s) for pure Ga2O3 at 250 °C for NH3 gas. Also the fast recover speed for NO2 (45 s) of 50% wt for CdO at 300 °C and (39.6 s) for NH3 for 50% wt of CdO at 300 °C .The maximum sensitivity of pure Ga2O3 200 ppm of NH3 about 48.2% while the maximum sensitivity of tested samples to 60 ppm of NO2 about 61.7% at around 300 °C for 75%wt .

Sensitivity and resolution are important parameters that pose a significant challenge in using microwave microfluidic sensors to monitor low-concentration binary liquid mixtures. This work presents a microwave split-ring resonator (SRR) sensor equipped with a substrate-embedded fluidic channel and an active feedback loop to enhance sensitivity and resolution, respectively. The substrate-embedded channel eliminated the impact of the liquid-carrying tubes' wall and maintained a significant interaction between the liquid in the channel and the electromagnetic (EM) field confined between the SRR and ground plane. Therefore, embedding the channel inside the substrate of the SRR sensor, operating at 2.63 GHz, enhanced the sensitivity by 60%. The constructive energy from the active feedback loop boosted the quality factor of the passive SRR by over 100x (from 116 to 13,000), which significantly enhanced the resolution of the sensor. As a proof of concept, two prototypes of the sensor having different substrate-embedded channels with cross-sectional diameters of 1 and 0.762 mm were fabricated and used to detect low concentrations of ethanol (0-0.08 vol%) and salt (0-200 mM) in water. Embedding the channel inside the substrate of the active SRR sensor achieved a linear correlation (R² = 0.99) between the resonant frequency and the concentration of ethanol and salt in water with high sensitivity (19.95 MHz/vol% for ethanol and 4.35 kHz/mM for salt) and resolution (0.001 vol% for ethanol and 2.298 mM for salt). The achieved results demonstrate the feasibility of using the active SRR microwave sensor with a substrate-embedded channel for monitoring ethanol in fermentation broths and electrolytes in human sweat.

This paper presents a slew-rate booster and frequency compensation circuit for automotive LDOs. The proposed circuit addresses three major LDO design challenges: frequency compensation for a wide range of output currents and load capacitors, fast response to load transients and reduced sensitivity to the supply variations. It was used to implement an LDO that provides a 5V output voltage and up to 50mA output current over a wide range of supply voltages - from 5.25V to 40V - and temperatures, -40°C to +150°C, while burning as little as 30μA. The slew-rate booster ensures that the output voltage overshoot and undershoot caused by load jumps of 50mA/μs remain below 4% of the nominal Vout value. Moreover, the LDO meets the E-06 test requirements within the LV124 automotive standard: the output voltage varies within 10% of its nominal value when sinusoidal voltages with amplitudes up to 20V peak-to-peak and frequency varying between 15Hz and 100kHz are injected into the LDO supply line. This feature is achieved while using a capacitor of only 1μF at the output, up to 10 times smaller than the decoupling capacitors used by similar LDOs reported previously.

The implementation of fully integrated frequency division duplexing (FDD) transceivers imposes many challenges, such as receiver (RX) desensitization by the transceiver (TX), reciprocal mixing, and sensitivity, to antenna voltage standing wave ratio (VSWR) variations. Here, we present the quadrature balanced N-path receiver (QBNR) architecture. The QBNR is composed of a quadrature hybrid and two identical mixers, presenting a short circuit and 50-Ω matching in the TX and RX bands, respectively. The TX power reflects at the mixers and reconstructs in-phase at the antenna, while the RX signal from the antenna can be reconstructed in phase at the baseband RX port. This architecture provides wideband FDD functionality while providing TX noise and local oscillator phase noise cancelation and antenna VSWR tunable compensation. Our implementation measurement results for an equalized configuration show more than 55-dB TX to RX isolation at frequencies of 1-2 GHz and for antenna VSWR of 2:1, with 3-dB TX loss and 4-dB RX loss, RX ${IP_{1,dB}}$ of 5 dBm and TX ${IP_{1,dB}}$ of 16 dBm, and receiver ${B_{1,dB}}$ of 10 dBm.

The receiver sensitivity is a very important metric in optical communication links operating at low received signal powers. Phase sensitive optical amplifiers (PSAs) can amplify optical signals without excess noise, thus providing a fundamental sensitivity improvement of 3 dB when employed as a pre-amplifier compared to conventional erbium doped fiber amplifiers (EDFA). In this paper, we investigate, both theoretically and experimentally, the sensitivities achieved using power efficient multi-dimensional modulation formats such as M-ary pulse position modulation format (M-PPM) and M-PPM combined with quadrature phase shift keying (QPSK) along with a near-noiseless PSA pre-amplified coherent intradyne receiver. We find that at high signal to noise ratios (SNRs) corresponding to low bit-error-rates (BER), M-PPM+QPSK results in the best sensitivity, which is improved with the order M, while at low SNRs corresponding to high BER (~14% where 100% overhead forward error correction codes (FEC) would be needed to recover the data), QPSK is the most sensitive format, while at the same time providing the best spectral efficiency. We report experimental sensitivities of 2.1 photons per information bit (PPB) at a pre-FEC BER=10-3 using 64-PPM+QPSK and assuming 7% FEC, and 0.8 PPB at a pre-FEC BER= 0.14 using QPSK and assuming 100% FEC.

A scalable system for wireless wear monitoring in a distributed harsh industrial environment, in which installation of the electronic equipment near the distributed wearing measuring locations is unfeasible, has been successfully designed, developed and deployed. The system is composed of a novel LC -type passive wireless wear sensor system, a sensor readout coil, an electronic equipment, a readout unit for a scalable multisensor system and a control and monitoring system. The capacitor structure, employed as a sensing device in the LC sensor manufactured on low cost PCB, provides a linear response to the wear level. This allowed us to define a measuring and calibration method to suppress the cable effects from each distributed readout coil to the electronic equipment readout unit. It was possible to achieve a multiple simultaneous measurements in different sensors distributed along an industrial process without significant cabling influence. Concerning the sensor data analysis, a double Holt-Winters method with trend was used to reduce noise effects and an “experience based learning” tool was implemented in order to solve any misbehavior or time lag. Laboratory measurements and on-site operation results in an article mill indicate 1 mm precision and about 0, 5 MHz/mm sensitivity of the LC -type passive wireless wear sensor system.

Radio frequency energy harvesting (RFEH) is very attractive for the Internet of things (IoT) and self-powered micro-systems such as wearable biomedical devices and wireless sensor networks. This paper proposes, analyzes, and implements a new RF-DC converter in standard 130 nm CMOS technology. The developed converter is designed and optimized for ultra-low-power IoT and wearable biomedical applications using the 900 MHz ISM band. The proposed 10-stage cross-connected rectifier compensates the transistors threshold voltage by using both dynamic and static bias compensation techniques. An analytical model of the rectifier based on the MOSFET transistor equations is presented, allowing optimization of the rectifier as a function of the number of stages and transistors sizing, improving the sensitivity and the input power range of the converter. The measurement results demonstrate a sensitivity of -25.5 dBm for 1 V output across a 5-MΩ resistive load and -29 dBm for a 100 MΩ load, which is better than the best previously reported results. The measured peak end-to-end efficiency of the proposed harvester is 42.4% at -16 dBm input power, delivering 2.19 V to a 450 kΩ load.

The cerebral pressure-flow relationship has directional sensitivity, meaning the augmentation in cerebral blood flow is attenuated when mean arterial pressure (MAP) increases vs MAP decreases. We employed repeated squat-stands (RSS) to quantify it using a novel metric. However, its within-day reproducibility and the impacts of diurnal variation and biological sex are unknown. Study aims were to evaluate this metric for: 1) within-day reproducibility and diurnal variation in middle (MCA; ∆MCAvT/∆MAPT) and posterior cerebral arteries (PCA; ∆PCAvT/∆MAPT); 2) sex differences. ∆MCAvT/∆MAPT and ∆PCAvT/∆MAPT were calculated at seven time-points (08:00-17:00) in 18 participants (8 women; 24 ± 3 yrs) using the minimum-to-maximum MCAv or PCAv and MAP for each RSS at 0.05 Hz and 0.10 Hz. Relative metric values were also calculated (%MCAvT/%MAPT, %PCAvT/%MAPT). Intraclass correlation coefficient (ICC) evaluated reproducibility, which was good (0.75-0.90) to excellent (>0.90). Time-of-day impacted ∆MCAvT/∆MAPT (0.05 Hz: p = 0.002; 0.10 Hz: p = 0.001), %MCAvT/%MAPT (0.05 Hz: p = 0.035; 0.10 Hz: p = 0.009), and ∆PCAvT/∆MAPT (0.05 Hz: p = 0.024), albeit with small/negligible effect sizes. MAP direction impacted both arteries' metric at 0.10 Hz (all p < 0.024). Sex differences in the MCA only (p = 0.003) vanished when reported in relative terms. These findings demonstrate this metric is reproducible throughout the day in the MCA and PCA and is not impacted by biological sex.

In the worst case, a temporary ignition source (also known as transient combustibles) between two electrical panels can damage both panels. Mitigation strategies for electrical panel fires were previously developed using fire modeling and risk analysis. However, since they do not comply with deterministic fire protection requirements, it is necessary to analyze the boundary values at which combustibles may damage targets depending on various factors. In the present study, a sensitivity analysis of input variables related to the damage threshold of two electrical panels was performed for dimensionless geometry using a Fire Dynamics Simulator (FDS). A new methodology using a damage evaluation map was developed to assess the damage of the electrical panel. The input variables were the distance between the electrical panels, the vertical height of the fuel, the size of the fire, the wind speed and the wind direction. The heat flux was determined to increase as the vertical distance between the fuel and the panel decreased, and the largest heat flux was predicted when the vertical separation distance divided by one half flame length was 0.3–0.5. As the distance between the panels increases, the heat flux decreases according to the power law, and damage can be avoided when the distance between the fuel and the panel is twice the length of the panel. When the wind direction is east and south, to avoid damage to the electrical panel the distance must be increased by 1.5 times compared to no wind. The present scale model can be applied to any configuration where combustibles are located between two electrical panels, and can provide useful guidance for the design of redundant electrical panels.

The detection of metal particles in oil is of great significance to the fault diagnosis of mechanical equipment. Real domain detection methods cannot simultaneously identify the sizes and materials of particles. Because a metal particle in an alternating magnetic field induces a complex domain signal whose strength relates to the particle properties, this paper introduces a double lock-in amplifier circuit (DLAC) into a triple-coil inductive particle sensor to detect the complex domain signal under noise interference conditions. Furthermore, various sizes of red copper, brass, aluminum, iron, and type 403 steel particles are chosen as the experimental materials. For the first time, the complex domain signals induced by the five kinds of particles are detected. Hence, in the complex plane, a method is proposed to identify the size and material of a particle based on the amplitude and phase of these signals. With the high sensitivity and strong antinoise ability of the DLAC, this system can detect 25 μm iron particles and 70 μm copper particles. This study presents a new strategy for the online detection of particles in oil.

Different from conventional radar systems, for the single-photon radar, a single-photon detector acts as the receiver to detect the echo signal with only a few photons, which can be used to achieve ultrahigh sensitivity for long-distance target detection. In this letter, the heterodyne single-photon radar at terahertz frequencies is studied, for the first time. First, the working principle of the developed heterodyne single-photon radar is presented, and the target echo signal is derived. Subsequently, the estimation method of the target distance and the Doppler frequency is proposed, and the performance is analyzed by probability density function (PDF) derivation. Simulation results show good agreement with the theoretical analysis. This work can pave the way to the development of a new radar paradigm.

In this study, CaF2–ZnO–P2O5–CaO–SiO2 system glass ceramics containing Ca5(PO4)3F nanocrystals were prepared via melting and crystallization, and their structure, up-conversion luminescence properties and energy transfer were investigated. Owing to the different temperature dependences of the three emitting bands at 523, 547 and 659 nm, dual-mode temperature measurement can be realized according to the employed fluorescence intensity ratio technology. Using thermal-coupled energy levels, the maximum relative sensitivity (Sr-max) and absolute sensitivity (Sa-max) were found to be 1.71% K-1 and 0.69% K-1, respectively. Moreover, the maximum relative sensitivity (Sr-max) and absolute sensitivity (Sa-max) were found to be 2.19% K-1 and 0.11% K-1, respectively, based on the nonthermal coupled energy levels. This shows that fluoroapatite transparent glass ceramics have latent application prospects in the optical temperature measurement field.

Complementary metal-oxide-semiconductor (CMOS) image sensors have widely been used in internet of thinking (IoT) devices such as smartphones, smart watch and personal computer tablets [1] . The consumer market strongly requires higher sensitivity and higher speed image data processing to realize high functional CMOS image sensors such as three dimensionally stacked back-side-illuminated CMOS image sensors (3D-CIS) [2] . However, there are some serious technological issues in the fabrication of advanced CMOS image sensors as shown in Fig. 1 .

This article reviews the recent advancements in the utilization of over-the-air combining techniques to enhance the efficiency of phased-array transmitters for signals with a high peak-to-average-power ratio. A methodological comparison between three spatial over-the-air combining techniques--Doherty, outphasing, and quadrature combining--is proposed, along with analysis of their spatial properties, such as a beamwidth angle for a given error vector magnitude (EVM) value, directivity, out-of-band emission, and sensitivity to amplitude and phase mismatches between the different streams. The analysis suggests that the Doherty technique has the widest spatial angle range with EVM under -30 dB and the lowest sensitivity to mismatches, while quadrature combining exhibits the lowest adjacent channel power ratio (ACPR). Also, the Doherty technique enables the largest efficiency enhancement and allows to trade off efficiency enhancement for out-of-band emission. The different methods were tested over-the-air at 28 GHz with a four-element integrated phased array fabricated in 65 nm to validate the analysis.

In this paper, a 13-level asymmetric configured cascaded H-bridge (CHB) inverter is used with a 54-pulse AC-DC converter to feed a medium voltage indication motor (IM). A thorough analysis is caried out to design an isolated multi-winding transformer (MWT) based 54-pulse converter. Accordingly, the main aim of this converter is to extract the power from the grid as per the power quality standard. Moreover, a higher number of voltage levels in CHB inverter is used to adhere the power quality due to asymmetric DC supplies, having 1:2:3 voltage ratio. Hence, a 13-leevl CHB-MLI is implemented with nine DC voltage sources. The converters of this drive system ensure that the quality of the grid currents and drive currents are excellent and meet the IEEE 519 power quality successfully. A nearest level control technique is implemented to generate the switching logic for a 13-level CHBCHB inverter. Simulated results demonstrate the performance of a 298.4kW induction motor drive in steady state and dynamic state. A validation study is conducted on an experimental setup with a 7.5kW IM at steady and dynamic states. Test results show a good agreement in terms of total harmonics distortions, power loss, and efficiency.

This work presents a 3-D-integrated opto-electrical receiver (RX) analog front end (AFE) operating up to 50 Gb/s. The electronic integrated circuit (EIC) is fabricated in ST SiGe BiCMOS-55-nm technology and flipped and mounted on top of the ST photonic integrated circuits (PICs) die through copper pillars (Cu-Pi). In the RX chain, a low-power fully differential shunt-feedback trans-impedance amplifier (FD SF-TIA) is exploited to reduce the input-referred noise. Following the TIA, a postamplifier (PA) based on a novel active feedback circuit topology extends the bandwidth (BW) and a buffer delivers the output electrical signal to the 100-Ω differential off-chip load. An automatic offset cancellation loop is included to protect the RX from any offset source at the input. The RX AFE consumes 56 mW from 1.8-V supply voltage and provides a trans-impedance (TI) gain of 78.7 Ω with 27-GHz BW. By exploiting the FD SF-TIA with low parasitic capacitance of the germanium photodiodes (Ge-PD) in the photonic die as well as BW recovery by the PA, the RX achieves the sensitivity of -7.5-dBm OMA at Ge-PD and -2.3-dBm OMA at the single-mode fiber (SMF) optical output with bit error rate (BER) of

The design of an ambient radio frequency (RF) energy harvesting system is introduced to replace the battery of the mass Internet-of-Things devices. This system can achieve high sensitivity with high efficiency over a wide input power range by optimizing the differential-drive cross-coupled (DDCC) rectifier and the load. The impedance of the dual-band four-port loop antenna array is directly conjugated to match with the rectifier, which reduces insertion loss of the matching network to improve efficiency. At 915 and 945 MHz for ISM and GSM bands, the rectenna can achieve high sensitivity of -30 dBm with 22% and 24% efficiency, high efficiency of 65% and 48% with -20-dBm input power, and a wide input power range from -30 to -18 dBm with 22-65% and 24-48% efficiency. The dual-band design explores the frequency diversity to harvest more RF energy from the environment, while the cross-shaped antenna array utilizes the space diversity to harvest RF energy from different directions with a compact size of 0.15λ x 0.15λ per antenna element (where λ is the free space wavelength at 915 MHz). This new harvesting system can provide output dc power of 21.4 and 2.95 μW in real-world outdoor and indoor ambient environments, respectively.

This work describes the development of an acoustic sensor based on piezoelectric ZnO thin film to be utilized for aero-acoustic measurements. The design of the device was carried out through CAD tool Coventorware. The backside of the device consists of the microtunnel and diaphragm structures. The Si-diaphragm thickness of the device was optimized for high sound pressure level (SPL) (upto 180 dB) using Coventorware. A microtunnel connects the cavity, created after diaphragm formation to the outside environment. The designed device has been fabricated using standard Si-fabrication technology. Microtunnel and diaphragm structures have been fabricated in a single step using wet etching technique which results in reduced cost as well as fewer number of process steps and increased yield of the device. The front side consists of a piezoelectric sensing layer of ZnO sandwiched between two sputter deposited electrode layers of Au covered with PECVD oxide on a thermally oxidized Si-diaphragm. The low cut-off frequency, bandwidth, resonance frequency and flat band sensitivity of the device have been found to be 35.2 Hz, 15 kHz, 78 kHz and 136.5 μV/Pa respectively. The fabricated device can be used for the SPL measurement in aircrafts, aerospace and similar applications.

This letter proposes and experimentally demonstrates an orthogonal frequency division multiplexing wavelength division multiplexing passive optical network (OFDM-WDM-PON) system based on novel chaotic set-partitioned selective mapping (SP-SLM) scheme. With the implementation of a three-dimensional chaotic system, peak-to-average power ratio (PAPR) reduction and chaotic encryption are simultaneously realized on the process of OFDM signal modulation, so as to enhance the system performance in the presence of PAPR, bit error rate (BER), fiber nonlinear tolerance and security. The experimental results show that, when compared with original OFDM signal, the OFDM signal with SP-SLM can achieve 4 dB PAPR reduction at the complementary cumulative distribution function value of $10^{-4}$ , as well as a 1.1 dB gain in receiver sensitivity at a BER of $10^{-3}$ . For fiber nonlinear tolerance, the optimal launch fiber power of OFDM signal with SP-SLM is 10 dBm, which is better than 9 dBm of original OFDM signal under the same received optical power of −16 dBm. Furthermore, the key space of the proposed scheme can reach up to $10^{98}$ , which is large enough to effectively protect against illegal attackers.

This paper presents a relative pressure sensor fabricated by a standard industrial flexible printed circuit board (FPCB) technology. The passive wireless sensor consists of a variable sensing capacitor and a planar coil inductor. When the external pressure is applied to the sensing capacitor, it changes the air gap and shifts the LC resonance frequency which is detected by an antenna wirelessly. The sensing cavity of the variable capacitor is extended to the opening at the end of an embedded pressure channel in the FPCB strip to enable relative pressure measurement. Measurement results showed that the proposed sensor with such an open sensing cavity had much higher frequency sensitivity (up to 0.4 %/mmHg) compared with the sensor with a sealed cavity (< 0.01 %/mmHg in this work and ≤ 0.08 in literature). With the enhanced sensitivity, the measured pressure resolution could reach 0.2 mmHg. The potential application of the proposed sensor includes gauge pressure measurement with respect to local atmospheric pressure, such as intracranial pressure (ICP) monitoring, without complicated re-calibration procedures. The flat FPCB structure facilitates applications with limited space for sensor installation, such as in the subdural implantation procedures. Furthermore, the proposed technology enables future development of flexible microfluidic devices.

The effects of the Zn/Mg ratio on the precipitate behavior and mechanical properties of Al-Zn-Mg-Cu alloys at different quenching rates were investigated by a Jominy end-quench test, tensile test and microstructural analysis. The results show that the hardness and strength of the aged alloys clearly decrease with increasing quenching distance (D). Additionally, the alloy with a Zn/Mg ratio of 5.42 has a more obvious drop in yield strength than the alloy with a higher ratio of 7.09 when D is varied from 10 mm to 142 mm. During slow quenching, fewer equilibrium η phases are formed in the alloy with a higher Zn/Mg ratio of 7.09, and then a larger number of fine η′ phases precipitate during subsequent aging, which reduces the quench sensitivity of the alloy.

An all-optical temperature sensor based on a fluorescence intensity ratio suitable for real-time monitoring of temperature in chemical reaction processes is proposed and experimentally demonstrated. The sensor can be used for online real-time measurement of the temperature of a chemical reaction system in a small and complex environment. The sensor probe was made of Er3+/Yb3+ co-doped TeO2–WO3–Na2O–ZnF2–Nb2O5 glass and combined with an all-optical sensor system using a discharge melting method. By making different Er3+/Yb3+ concentrations of glass, Er3+/Yb3+ co-doped TeO2–WO3–Na2O–ZnF2–Nb2O5 glass with the best luminescence intensity was explored, and the influence of different excitation powers on the sensing of high-power excitation light material sensing was analyzed. The thermal and optical properties of the material were analyzed, and the possibility of using it as a temperature sensor material was discussed experimentally and theoretically. The maximum temperature sensitivity of the sensor is 0.0067 K-1. Finally, it was applied in the actual chemical reaction.

This paper presents a polyimide-based film bulk acoustic resonator (PI-FBAR) humidity sensor operating in resonant frequency and reflection coefficient S11 dual-mode. Models and experiments showed that those two modes are governed by different mechanisms, of which the former is based on the modulation of the humidity on the Young’s modulus of PI, while the latter is based on the modulation of the humidity on dynamic resistance. In the full-scale relative humidity (RH) testing range (20%-80%), the resonant mode achieved a sensitivity of 29.93 kHz/%RH (28.56 ppm/%RH) with ultra-high linearity (R2 = 0.9993), and the humidity hysteresis error is only about 1.32% RH. For the S11 response, an ultra-high average humidity sensitivity of 0.044dB/%RH (2095ppm/%RH) was achieved, and the sensitivity at 20% low relative humidity reached 0.075dB/%RH (3571ppm/%RH), which is more than 2 orders of magnitude higher than that of the resonant frequency response. And the limit of detection (LOD) for the humidity response of S11 is 0.035% RH, which is half lower than that of the resonant mode. Thus, we can choose a more appropriate sensing mode according to particular application or combine these two mechanisms in one test to expand the sensor competences by taking advantages of each method. In addition, as both of the two modes have high sensitivity to humidity and temperature, we deduced a method to calibrate the temperature for the humidity sensing. Based on this dual-mode mechanism, we can further achieve either temperature-calibrated humidity sensing or dual-variable sensing of humidity and temperature with more accurate sensing results.