Sensor Circuit Research Articles

Groundwater feasibility test system by using wireless sensor network

Water is one of the most important natural resources for human life. Water is used by the community for bathing, drinking, cooking and for other consumptive needs. Therefore, the water quality must be maintained cleanly. It is not uncommon to find water that is not suitable for use because it is turbid and smelly from its source. Things that must be considered to assess good water quality are pH, oxygen levels dissolved in water, conductivity, water temperature, water turbidity, salinity (salt content), zinc content and so on. The testing of groundwater quality is a better alternative than the testing that has been done manually and requires expensive costs. The measuring devices are made by using sensor circuit that is controlled by Arduino. Monitoring is done by using a web application that is stored on a server where the server also communicates with Arduino with the help of the SIM800L module. The results showed that the system ran well. The sensors succeed in detecting water quality and data communication between sensors, servers and clients ran well.

A New Approach for Effective Biomedical Waste Segregation and Disposal

Biomedical waste management is a major concern in current scenario. Increase in hospital and health care facilities also generates high amount of biomedical waste. Therefore, segregation, handling and disposing of waste is crucial step to be taken. Waste segregation is to be done according to the color-coded dustbins as per the rules formed by the “The ministry of environment, forest and climate change”. Segregation into color coded dustbin is done on the basis of type of category of waste. If proper segregation of biomedical waste is not done, then the further process of handling and disposing of it becomes laborious. As different kind of waste is treated (reused, recycled and reduce) in distinct way. Not only this but the waste discarded improperly can be harmful to the environment and toxic to the people coming into contact with them invariably while disposing or treating the medical waste. Thus, we are developing an instrument which segregates biomedical waste effectively and dispose it having minimum human exposure with the it while and after disposal. We start with a matrix constructed using switches and LED lights of different colors which indicate the respective color code of the dustbins. The rows and columns describe the different properties of the waste material. Each of the dustbins has an ultrasonic distance sensor attached in front of them followed by a microcontroller and servo motor. The distance sensor circuit controls the lid of the dustbin when person goes near/away from the dustbin. This is how hospital waste segregation is done fruitful and disposal of it in such a way that chances of spreading infection through medical waste decreases. Later, it can be discarded in bigger bins for storing and transporting it to waste management companies.

Acoustic energy harvesting from trace gas analyzing sensor

In this study, a trace gas analyzing sensor is utilized for energy harvesting. The laser beam with a range of one meter is directed to the photo-acoustic cell and creates acoustic waves by absorbing gas molecules. The captured acoustic signal is converted into an electrical signal by the microphone and then processed by custom-designed electronic circuits to transform current to voltage, to amplify, and to reduce total harmonic distortion of the signal.Voltage multiplier (VM) is used at the end of the sensor circuit for energy harvesting to obtain DC voltage. Acquired resonance signal has multiple sinusoidal structure and contains harmonics so the effect of capacitance on VM’s stage is analyzed and demonstrated that the mean value of DC has been boosted and the ripple has been reduced through high capacitance values. It is observed at the output of one to ten stages VM that the mean voltage increases from 8.5 V to 32.55 V and fit to third order polynomial and the average power rises from 72.23 μW to 1.06 mW. Our results show that acoustic energy harvesting with a sensor has the potential to provide partial or complete electrical energy for the sensor used.

16.8 nW Ultra-Low-Power Energy Harvester IC for Tiny Ingestible Sensors Sustained by Bio-Galvanic Energy Source.

Herein, we present a 16.8 nW ultra-low-power (ULP) energy harvester integrated circuit (IC) for ingestible biomedical sensors. The energy harvester can be powered from the electro-galvanic operation inside a human body, which provides a sustainable and long-term energy source. The challenge of dealing with relatively high input impedance (∼kΩ) of the bio-galvanic energy source is addressed by introducing two design techniques. The first technique is an adaptive VMPP-controlled algorithm (AVCA) for a maximum power point tracking (MPPT) controller, and the second technique is a ULP delay-line-based zero current switching (ZCS) controller. Different from the conventional fractional open-circuit voltage (FOCV) method for MPPT, the proposed AVCA allows continuous source tracking without detachment of the harvester from the source. The ZCS operation is achieved using a delay-line controller without using either a comparator or an opamp. The proposed AVCA is realized using a 12.1 nW MPPT controller. Successful ZCS operation is achieved using a 2.1 nW delay controller. Overall power consumption of the IC is 16.8 nW. The converter has been fabricated in a 0.18μm CMOS process with 2μm thick top-metal option. The measured result shows that the converter achieves a peak efficiency of 72.1% to generate 507 nW output power. The ULP operation allows a significant reduction in electrode size down to the submillimeter scale (∼0.4mm2), demonstrating the good potential of the proposed energy harvester IC.

Research on Electrical Automation Metal Pipe Cutting Device

This article analyzes the key points in the design of electrical automation metal pipe cutting devices. The content of this article includes cutting principle analysis, power supply structure design, transducer design, horn design, controller selection, touch control screen circuit design, sensor circuit design, emergency stop control circuit design, executive circuit design, etc. The author studied the amplitude detection experiment, process parameter experiment, cutting experiment analysis, etc., whose purpose is to improve the orderliness of the metal pipe cutting process and improve the final construction quality of the pipe.

Design of formaldehyde concentration detection system for smart home based on STM32 controller

It is a well-known thing that formaldehyde can seriously endanger human health. During decoration, some decoration materials, including furniture, will contain a large amount of formaldehyde, and some wall paint will also emit a lot of formaldehyde. Therefore, how to judge that the harmful gas in a house exceeds the standard has become a headache. In response to this problem, this article has designed an intelligent formaldehyde detection system, which can accurately detect the concentration of harmful gases in the room and then alarm. The operation is simple.The system consists of STM32F103C8T6 microcontroller circuit, LCD1602 liquid crystal display circuit, and formaldehyde detection sensor circuit. The voltage value and formaldehyde concentration value before formaldehyde conversion can be displayed in real time as the formaldehyde concentration changes. If the concentration of formaldehyde in the air is higher than the body’s tolerance range, the buzzer will sound a “beep” alarm, otherwise it will not sound.

Photoelectric Sensor Circuit and Image Segmentation Method for Radar System

In this exploration, based on the principle and system parameters of laser three-dimensional (3D) radar imaging technology, the corresponding photoelectric sensor circuit scheme is formulated. The sense circuit of avalanche photon diode (APD) converts the signal through the transresistance amplifier circuit. Then, LMH6629 is selected as a precision amplifier with low input noise voltage and low input error current. The capacitance is used as a compensation element to compensate the phase. For the power supply scheme, choosing the mode of switching power supply and LDO to work together can improve the efficiency of power supply and reduce the output of current ripple. At the same time, semantic segmentation is carried out for the obtained photoelectric images. Based on the traditional spatial pyramid pooling algorithm, the fusion of mean intersection over union and cross information entropy loss function is introduced to improve the weight of local image region. In the experiment, Multisim software is used to simulate the circuit. The APD reverse bias voltage is set to 90 V, and the multiplication coefficient is 98.7. The feedback resistance, bandwidth, phase compensation capacitance and other parameters are further calculated. It is found that there is obvious self-excited phenomenon in the output waveform of the transresistance amplifier without phase compensation capacitor. When the feedback capacitance reaches 0.8 pF, the oscillation phenomenon is obviously reduced; further calculation shows that the bandwidth of transresistance amplifier is 230 MHz, and the noise of APD power supply is mainly caused by BUCK switching power supply switch when the bottom noise of oscilloscope is ignored. However, the noise is suppressed under the action of the back-end LDO device; after the loss function is introduced, the contour of the photoelectric image is preserved completely, and then the more accurate segmentation results are obtained.

DNA Circuits-Based Signal Amplification for Ultrasensitive Nucleic Acids Detection

Nucleic acids detection has significant meanings in disease diagnosis, monitoring of environment and so on. However, only trace concentration of nucleic acids exists in specimen. Ultrasensitive nucleic acids detection is required based on the strategies of signal amplification. Currently, DNA nanotechnologies are employed to amplify the detecting signal, mainly including DNA hybridization-based sensors and DNA circuits-based sensors. DNA circuits-based sensors have higher sensitive than that of DNA hybridization-based sensors, which attract the attention of researchers. With this view, we present an overview of DNA circuits-based amplification strategies for nucleic acids detection with fluorescent sensors and electrochemical sensors, respectively. It mainly contains duplex specific nuclease (DSN)-based DNA circuits and strand displace reaction (SDR)-based DNA circuits, which enable nucleic acids to trigger DNA circuits without consumption. The strategies can multiply the increase of the signal of nucleic acids with simple operation. Meanwhile, this review discusses the current challenges and future outlook of DNA circuits in sensors. We envision that our review provides implications to promote the development of DNA circuits-based biosensors for nucleic acids detection.

Construction, Application and Verification of a Novel Formaldehyde Gas Sensor System Based on Ni-Doped SnO2 Nanoparticles

An efficient formaldehyde (HCHO) gas sensor system based on nickel-doped tin oxide (Ni-doped SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) nanoparticle sensor and back-end circuit has been developed. Ni-doped SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanoparticles are prepared by a simple one-step hydrothermal method. To complete the function of detecting HCHO gas in real time, a back-end circuit suitable for resistance measurement of nanoparticle sensors and an organic light emitting diode screen which can display the output of gas concentration data are integrated as a portable device. Compared with the traditional HCHO detection device, this designed system exhibits better stability, excellent selectivity, and high response. Its detection limit is as low as 90 ppb. The gas response to 50 ppm HCHO is 67.63. Further for the quantitative evaluation, we refer to and modify the existing HCHO diffusion model, then carry out a practical test on the HCHO diffusion at the same time. The comparison between the theoretical fitting curve and the actual test curve matched well enough to reflect the potential of this system for the practical HCHO evaluation.

W-MOPSO in Adaptive Circuits for Blast Wave Measurements

Optimizing the adaptive circuit of piezoelectric sensors is important in accurately measuring blast waves. This study analyzed the impact of the bandpass cut-off frequencies and quality factor of adaptive circuits on shock wave measurements. We proposed a Multi-objective particle swarm optimization based on weighted Pareto-dominance sort (W-MOPSO) for optimizing the multi-objective function of an adaptive circuit in order to improve precision during shock wave measurements. W-MOPSO obtained a Pareto-optimal solution set through Pareto-dominant sorting of global optimal solutions to the weighted sum of a multi-objective function. The relative mean error in the optimized adaptive circuit mostly ranged between −2% and +2%. Simulations were used to analyze the impact of the optimized adaptive circuit on shock wave measurements. The effectiveness of W-MOPSO was verified through a real-world experiment using a TNT explosive and blast wave gauges. W-MOPSO provided a basis for adapter circuit design and optimization in shock wave measurement.

Current Ripple Prediction and DPWM Based Variable Switching Frequency Control for Full ZVS Range Two Parallel Interleaved Three-Phase Inverters

In this article, an improved variable switching frequency zero-voltage switching (ZVS) control strategy is proposed for two parallel interleaved three-phase inverters. Discontinuous pulsewidth modulation is adopted and full-range ZVS can be achieved at any load or modulation ratio. The critical switching frequency can be easily calculated in a digital controller based on current ripple prediction instead of current zero-crossing detection. No additional high-frequency sensor or auxiliary circuit is needed. Compared with the continuous pulsewidth modulation, the switching frequency variation range is narrower and the frequency calculation equation is simplified. In addition, lower peak current ripple leads to lower current stress. Owing to the high switching frequency and the low inductance, the size and the cost of the inverter can be significantly reduced. A 6.6-kW experimental prototype with SiC MOSFETs interfacing 400-V dc with three-phase 110-V ac grid is developed to verify the effectiveness of the proposed control strategy.

Low Bit-Depth ADCs for Multi-bit Quanta Image Sensors

A 1024 $\times $ 896 test chip is presented in this article to explore a low-power readout circuit for a multi-bit quanta image sensor (QIS). Five well-known analog-to-digital converter (ADC) approaches [flash, pipeline, successive approximation register (SAR), cyclic, and single-slope (SS)] are studied, and two types of ADCs, namely, SAR ADCs and SS ADCs, are implemented in the sensor. The ADC power dissipations are compared under the condition of constant imaging throughput in counting photoelectrons. In QIS devices, one LSB corresponds to one photoelectron. Measurement results show that the power consumption of SAR ADC is better than that of the SS ADC and decreases by a factor of 17 when the resolution is changed from 1 b to 6 bits. By contrast, the power consumption of the SS ADCs decreases by a factor of 2.5. Thus, SAR ADCs seem more suitable for use in low-power multi-bit QIS.

Integrating Metamaterial Antenna Node and LiFi for Privacy Preserving Intelligent COVID-19 Hospital Patient Management.

Light fidelity (LiFi) and wireless fidelity (WiFi) can be applied with the same network under the different constraints, which is suitable for COVID-19 surveillance in hospitals. The LiFi network is a high-capacity and security platform. A COVID-19 surveillance system using LiFi is proposed, which consists of two switching modes: communication and surveillance. Firstly, the communication targets are to accommodate the electromagnetic interference (EMI) immunity and high-capacity and security data transmission, where secondly the COVID-19 surveillance can be applied. In operation, the up and downlink system uses a metamaterial antenna embedded by Mach Zehnder interferometer (MZI). An antenna consists of silver bars embedded at the microring center with two-phase modulators at its sides. The entangled source namely a dark soliton is applied to form the transmission, where the information security based on quantum cryptography can be managed. By using the suitable parameters, the whispering gallery modes (WGMs) are generated and the up and downlink nodes are formed. The input information is multiplexed with time to form the multiplexed signals, where the big data transmission (40 Pbit {mathrm{s}}^{-1}) can be employed. By using the surveillance mode, the plasmonic antenna can be applied for temperature and electric force sensors, which can offer the disinfectant spray and temperature sensor for COVID-19 applications. The optimum plasma force sensitivity is 0.16 N kg−1 mW−1. The center frequencies of 191.48 THz and 199.41 THz are obtained for uplink and downlink antennas, respectively. The optimum temperature sensitivity is 0.05 rads−1 °C−1. In conclusion, the novelty of proposed work is that the integrated sensor circuits are employed for COVID-19 surveillance in the hospital. The fuzzy-based system is designed for critical patient monitoring alert using this surveillance and management inside the hospital for COVID-19 patients.

An Innovative Successive Approximation Register Analog-to-Digital Converter for a Nine-Axis Sensing System

With nine-axis sensing systems in 5G smartphones, mobile power consumption has become increasingly important, and ultra-low-power (ULP) sensor circuits can decrease power consumption to tens of microwatts. This paper presents an innovative successive approximation register analog-to-digital converter, which comprises fine (three most significant bits (MSBs) plus course conversion (11 least significant bits (LSBs)) capacitive digital-to-analog converters (CDACs), ULP, four-mode reconfigurable resolution (9, 10, 11, or 12 bits), an internally generated clock, meta-detection, the switching base midpoint voltage (Vm) (SW-B-M), bit control logic, multi-phase control logic, fine (three MSBs) plus course conversion (11 LSBs) switch control logic, phase control logic, and an input signal plus negative voltage (VI + NEG) voltage generator. Then, the mechanism of the discrete Fourier transform (DFT)-based calibration is applied. The scalable voltage technique was used, and the analog/digital voltage was Vanalog (1.5 V) and Vdigital (0.9 V) to meet the specifications of the nine-axis ULP sensing system. The CDACs can reconfigure four-mode resolutions, 9–12 bits, for use in nine-axis sensor applications. The corresponding dynamic signal-to-noise and distortion ratio performance was 50.78, 58.53, 62.42, and 66.51 dB. In the 12-bit mode, the power consumption of the ADC was approximately 2.7 μW, and the corresponding figure of merit (FoM) was approximately 30.5 fJ for each conversion step.

Improved Controller and Design Method for Grid-Connected Three-Phase Differential SEPIC Inverter

Single-ended primary-inductor converter (SEPIC) based differential inverters (SEPIC-BDI) have received wide concerns in renewable energy applications due to their modularity, galvanic isolation, decreased power stages, continuous input current, and step up/down capability. However, its design still has several challenges related to component design, the existence of complex right half plane (RHP) zeros, and increased sensitivity to component mismatches. In this context, this paper presents an improved control and enhanced design method for the three-phase SEPIC-BDI for grid-tied applications. A generalized static linearization approach (SLA) is proposed to mitigate the low-order harmonics. It practically simplifies the control complexity and decreases the required control loops and sensor circuits. The mismatch between the SEPIC converters in each phase is highly mitigated due to the independent operation of the SLA in each phase and the output dc offset currents are reduced. The proposed enhanced design methodology modifies the SEPIC open-loop transfer function by moving the complex RHP zeros to the left half-plane (LHP). Therefore, a simple proportional-integral (PI) controller effectively maintains converter stability without adding higher-order compensators in the literature. Moreover, a straightforward integrator in the control loop eliminates the negative sequence harmonic component (NSHC) and provides a low computational burden. Simulations and experimental results based on 200V, 1.6 kW, 50 kHz prototype with silicon carbide (SiC) devices are provided to validate the effectiveness of the proposed work. The results show that the proposed controller and design method achieve pure output current waveforms at various operating points of the inverter and dc voltage variations.

超小型磁歪式振動発電デバイスと高効率電力変換回路の提案

In this study, a magnetostrictive vibrational power generator was proposed for high-frequency vibration occurring in a machine tool and high-efficiency power conversion circuit for a battery-free wireless sensor. A conventional device was miniaturized according to the scale effect, and a device composed of a Fe-Ga alloy plate, of 2×0.25×8 mm3 with a frame of 0.5 mm thickness, was fabricated and evaluated. As a result, a generated voltage of 2 V and effective power of 234 μW were confirmed at a vibration of 522 Hz and 10 m/s2. In addition, the operating principle was verified in the power conversion circuit composed of an LC circuit (resonant circuit), a diode and a storage capacitor. As a result, it was confirmed that by using a large inductance, the Q value could be increased, and a considerable amount of energy could be stored in a 330 μF capacitor.

The Novel CPW 2.4 GHz Antenna with Parallel Hybrid Electromagnetic Solar for IoT Energy Harvesting and Wireless Sensors

The design and implementation's novelty simultaneously utilizes the antenna's frequency, polarization, and feed structure to maximize the harvested RF energy and become a microstrip communication circuit for wireless sensor or communication systems in IoT devices. In addition, the optimization of the parallel circuit configuration has a voltage doubler model with an integrated parallel system and thin-film solar cells. Implementation of the antenna structure has two-line feeds in one antenna. Usage both feeds have the same function as CPW circular polarization. Another advantage is that there is no miss-configuration when installing the port exchanges when using both output ports simultaneously. The 2-port antenna has an area of 1/2 per port (where accessible wavelengths work well at the 2.4 GHz frequency). It has been shown to achieve a relatively narrow bandwidth of 86.5 percent covering WiFi frequency band networks and IoT communications. It does not require additional filters and analog matching circuits that cause power loss in the transmission process in parallel voltage doubler circuits. Integrating a reflector on the CPW antenna with two ports for placement of thin-film solar cells provides antenna gain of up to 8.2 dB. It provides a wide beam range with directional radiation. Using a multi-stage parallel to increase voltage output and integrated with a thin-film solar cell converter proves efficient in the 2.4 GHz frequency band. When the transmission power density is -16.15 dBm with a tolerance of 0.023, the novel energy harvester configuration circuit can produce an output voltage of 54 mV dc without adding solar cell energy. And Integrated thin-film solar cell a light beam of 300 lux in the radiation beam area of -16.15 dBm, the energy obtained has a value of 1,74467V. It also shows that the implementation of this configuration can produce an optimal dc output voltage in the actual indoor and outdoor ambient settings. The optimization of antenna implementation and the communication process with Multiple signal classifications improves the configuration of antennas that are close to each other and have identical phase outputs. It is instrumental and efficient when applied to IoT devices.

A Dual-Slope-Based Capacitance-to-Time Signal Conditioning Circuit for Leaky Capacitive Sensors

A robust signal conditioning circuit for capacitive sensors, based on the dual-slope and phase-sensitive-detection technique, is presented in this article. The circuit is designed to measure the capacitance of the leaky capacitive sensors. The phase-sensitive-detection technique mitigates the effect of the shunting conductance. In addition, the circuit is designed in such a way that the error due to the parasitic/stray capacitance on the measurement of the sensor capacitance is negligible. Furthermore, an autotuning frequency-independent quadrature phase-shifter circuit is designed for an accurate 90° phase generation. A prototype of the circuit is built and tested. The experimental results show that the designed circuit can measure the sensor capacitance in the range from 65 to 528 pF with accuracy within ±1%. The robustness of the proposed circuit is tested against the variation in the amplitude and frequency of input sinusoidal excitation signal. The results confirm that the proposed circuit is well suited for sensors, such as capacitive humidity sensors, water level detection sensors, and fingerprint sensors.

High-Linearity Front-End Circuit for Remote Grounded Capacitive Sensors

This article presents a novel front-end circuit for remote grounded capacitive sensors. The circuit is insensitive to amplifier input capacitance and stray interconnecting-cable capacitances. It does not rely on neutralization or compensation techniques that require manual adjustments and high-accuracy reference components. The proposed solution reduces the circuit input capacitance below a few femptofarads using a simple but properly shielded custom transformer. In addition, the circuit keeps a nonlinearity error below 0.01% when measuring capacitances of units or tens of picofarad, even with up to 12-m interconnecting cables.

Fast and Robust Position and Attitude Estimation Method Based on MARG Sensors

With the development of Internet of Things (IoT), people’s demand for location-based services is increasingly urgent. Based on magnetometer, accelerometer, and rate gyro, i.e., MARG sensors, the position and attitude estimation methods such as complementary filter (CF), Kalman filter (KF), and their various modifications have been the research hot spot. However, the CF-based methods are empirical and lack robustness; the KF-based methods are memory-free observers, whose solution may diverge when the filter lacks uniform observability. In this article, a virtual-measurement-combined extended KF (VMC-EKF) method is proposed by fusing the carrier’s motion state with EKF method. Similar to the graph optimization, the proposed method can measure the key information in VMC phase, and thus remove the requirement of uniform observability. The number of virtual measurements can be estimated based on carrier’s motion state and its gradient, which determines the number of iterations of the prediction phase and the correction phase. In order to verify the performance of the proposed method, a series of numerical simulation experiments, turntable experiments, and foot-mounted experiments are carried out. The corresponding testing platform is set up based on MPU9250, which is a typical and low-cost motion tracking integrated circuit (IC) of MARG sensors. The raw data of MARG sensors can communicate with the host computer via wired or wireless communication, and then be imported into MATLAB for processing and analysis by the compared methods. The test results show that the proposed method can achieve fast convergence of attitude estimation and avoid the divergence of position estimation compared with the state-of-the-art methods.