Sensor Circuit Research Articles

Monolithic three-dimensional hafnia-based artificial nerve system

Artificial nerve systems that mimic the tactile perception ability of human skin could be adopted in the realization of devices for a hyperconnected society, including prosthetic devices, interfaces for virtual reality, and smart sensors. The system consists of a pressure sensor, memory, and signal processing circuit, which possess the capability of generating sensory neuron-like signals. Although technological advances have been made in semiconductor-based memory and transistors over the decades, sensor technology is still relying on micro-electromechanical systems, which are hard to realize miniaturization/high-density and high-performance technology. Here, we demonstrate a monolithic three-dimensional integrated artificial nerve on the basis of ferroelectric HfxZr1-xO2 for use in the core element of neuromorphic memory and a self-powered piezoelectric pressure sensor. The morphotropic phase boundary (MPB) state of hafnia film was formed between orthorhombic and tetragonal phases for high piezoelectric performance. The MPB-based sensor was integrated with self-rectifying ferroelectric tunnel junction memory and silicon-based ring oscillator. We realized a frequency-modulated pulse-like synaptic signal with pressure detection ability over a wide range of 1–50 kPa and a good sensitivity of 0.35 mV/kPa. Also, we demonstrate the real-time frequency-modulated operation of the artificial nerve system by adjusting the functional properties of the hafnia films.

Performance Evaluation of Micro Automatic Pressure Measurement Sensor for Enhanced Accuracy

The major objective of this research is to design sensitive components, conversion components, and various sensor circuits to achieve the miniaturization design for more accurate measurements. This article conducts performance testing on the designed miniaturized pressure sensor to determine whether it meets the qualified standards. The response time of designed sensor results increases with the increase of pressure under experimental conditions of different pressure application values (5MPa to 50MPa). The detection accuracy of the micro automatic pressure measurement sensor designed in this paper can reach 0.0452\%; the average pressure is 0.00364%, and the insulation resistance is 68.44 megohms, which meets reliability requirements. The sensitivity is 0.0582%; the nonlinearity is 0.0741%; the hysteresis is 0.0266%; the repeatability of 0.0625% meets the qualification standard for this instrument. Still, compared with traditional sensors, the sensor reduces the response time of results by about 60%. However, the author conducted the detection in an ideal environment. The actual working environment of sensors is relatively good. Therefore, the detection results obtained in this article may have some errors compared to the actual situation, and further analysis and testing are needed to optimize the performance of the designed sensor.

Circuit design solutions for underwater detection robots

In recent years, the exploration and utilisation of the environment has become in full swing with the advancement of technology. However, the environment has also suffered a certain degree of damage in the process. As a result of the increasingly serious environmental problems, various environmental issues have become hot spots in society. Among them, marine environmental problems have undoubtedly become one of the focuses of attention. Therefore, the robot design for underwater water quality detection has become an important issue. This paper will mainly focus on the design and research of the hardware circuit system of the underwater detection robot, and give the relevant design scheme. The underwater robot will achieve the following functions: floating suspension at a certain depth in the ocean; synchronously detecting the radiation intensity of x-rays and -rays underwater and transmitting the data to the ground to achieve real-time monitoring; maintaining the dynamic balance in the water. Therefore, this paper analyses the pressure sensor circuit, the inertial sensor circuit, the underwater x-ray and -ray detection probe circuit and the DC motor drive circuit, determines the interface relationship of each part, and at the same time, uses the Arduino mega 2560 as the control panel, and provide the appropriate voltage according to the needs of each circuit to achieve the hardware circuit design of the robot.

Wearable strain sensor utilizing the synergistic effect of Ti3C2Tx MXene/AgNW nanohybrid for point-of-care respiratory monitoring

Respiratory signals are significant indicators for detecting changes in physiological conditions and early diagnosis of numerous respiratory illnesses. Herein, we have integrated a high-performance strain sensor and portable circuit board (PCB) with personalized interface to develop point-of-care respiratory monitoring device. The ultrasensitive strain sensor utilizes a conductive polymeric nanocomposite that harnesses the synergistic effect of Ti3C2Tx (MXene)/AgNW nanohybrid to develop a wearable device. The wearable device is capable of analysing pulmonary volumes, such as forced volume capacity (FVC) and forced expiratory volume (FEV1), while accurately recognizing various breathing patterns in a resting state (such as normal, forced, and obstructive), as well as during different physical activities. It shows excellent correlation (>93%) with commercial spirometer for measurement of pulmonary parameters. In addition, we present a wireless device for lab rat respiratory monitoring in anaesthetic state. The device is implemented for real-time respiratory monitoring under mild, normal and high anaesthesia doses. The levels of anaesthesia doses including a critical limit can be significantly discriminated by means of breathing frequency and amplitude, which ultimately results in saving their lives. These results demonstrate the practical feasibility of the strain sensing device as wearable electronics for point-of-care respiratory monitoring in humans and other species.

Dynamic Monitoring and Analysis of Dual-Axis movement of SPV Power Plant Parameters under various Atmospheric Conditions

This research paper presents comprehensive insight into the testing of a 1 KW sun tracking photovoltaic (PV) performance. The study uses a state-of-the-art real-time string monitoring system to allow this analysis while covering an extensive variety of atmospheric conditions. The design of the 1 KW solar tracker system incorporates a tracking sensor circuit, motor driver circuit, string monitoring system, and solar tracker control circuit. Solar tracking systems boost energy generation by adjusting the angle of PV panels to optimum sunlight exposure. The effectiveness of such devices can, however, be severely impacted by atmospheric changes. In a photovoltaic (PV) facility, we have successfully developed and placed into use a real-time system for monitoring certain strings. The system collected data on key parameters such as current, voltage, and temperature, providing insights into the health and efficiency of each string. Our study encompassed various atmospheric conditions, including clear skies, cloudy days, and fluctuating solar radiation. A DAQ system developed communicate with observations such as the voltage and current of photovoltaic arrays and the voltage and current of DC motors. When comparing the dual-axis tracking system to the static PV system, a maximum of 48% more electricity can be extracted. Both days with clear skies and days with clouds provide satisfactory results. The supply for the tracker control circuit comes from PV cells. Therefore, there is no need for any auxiliary supply, such as a battery.

Splicable random windowing row selection circuit for large array CMOS image sensor

This paper presents a splicable random window row selection circuit applied to large array CMOS image sensors (CIS) for exposure and readout of certain pixel rows in large array CIS. The row selection circuit consists of coarse decoding and fine decoding circuits, utilizing two-stage address selection operations for precise row selection. The coarse decoding address is used to enable the splicing module of the large array CIS, while the fine decoding address is used to enable a specific row in the selected splicing module. This solves the problem of output redundancy caused by the same row address bits in different splicing blocks in the large array CIS. The paper introduces an improved bilateral driving technique, reducing the transmission delay to 1/4 of single-sided driving while ensuring timing consistency with coarse decoding circuits. This technique is applied to large arrays of CIS with dimensions of 8520 × 9448, successfully realizing the random window function.

Systematic Review on Fabrication, Properties, and Applications of Advanced Materials in Wearable Photoplethysmography Sensors

AbstractPhotoplethysmography (PPG) technology enables the measurement of multiple physiological and psychological parameters with low‐cost wearable sensors and is reshaping modern healthcare. Advanced materials play a vital role in improving reliability and accuracy of PPG sensors. Recently, various advanced materials have been explored to optimize PPG sensor design, while some challenges exist toward large‐scale validation and mass production. This paper focuses on advanced materials applied in the photodetectors, light sources, and circuits of PPG sensors. The materials are categorized into four groups: inorganic, organic, nanomaterials, and hybrid materials. The properties and fabrication processes are summarized. Other technical details including the mode of operation, measurement sites, testing, and validation are discussed. The merits and limitations of the state of the art are highlighted to provide some suggestions for the future development of PPG sensors based on advanced materials.

Equivalent circuits in nanopore-based electrochemical systems

Single-nanopore membranes constitute physical models for biological ion channels and are also central to electrochemical energy transducers, logical circuits in sensors and actuators, and converters in bioelectrical interfaces. The membrane potential, defined as the electrical potential difference established between two different ionic solutions separated by the membrane, is crucial for the electrical coupling of nanofluidic concentration cells to electronic components such as load capacitors and resistors. Here we analyze, theoretically and experimentally, the validity of basic principles governing electric circuit theory such as the Thévenin equivalent circuit, the additivity of voltages and resistances, and the Millman theorem in nanopore-based concentration cells. To this end, we consider a wide range of practical conditions with respect to salt concentrations, nanopore asymmetry, electrical capacitances, and series and parallel arrangements. Additionally, we investigate the scaling of the single pore results to the multipore case. The results obtained suggest that basic circuit models offer approximate tools to guide the analysis of the nanofluidic concentration cells.

A new shadow resistance to frequency converter as a read‐out circuit for resistive sensors

SummaryThis paper presents a new resistance to frequency converter. The design is based on a shadow signal generator that produces square and triangular waveforms. The oscillator frequency can be changed using an external circuit (shadow oscillator). This method will make the conversion speed better than the conventional oscillators, and the frequency varies linearly with the resistance variation. The circuit is built using widely available commercial integrated circuits, and powered from a ±5‐V DC supply. The recommended setup is suitable for instrumentation where the oscillation frequency is directly proportional to the variation in the resistance of the sensor. The functionality of the proposed design was confirmed by experimentation and simulation. The oscillation's frequency can be changed to be nearly 10 times greater than its starting value, according to the results.

A novel double-sided fabric strain sensor array fabricated with a facile and cost-effective process

Electronic textiles face challenge in fabricating stretchable, double-sided circuits with reliable interfaces. In this study, a double-sided strain sensor array was designed and prepared on an elastic fabric substrate by printing the sensing areas and interconnects using a single identical conductive composite paste. By controlling the viscosity of the printing paste, the conductive tracks on both sides of the porous fabric were insulated, except for the via holes at the specified positions. Through fabrication using a facile and cost-effective method, the fabric strain sensor array exhibited preferable consistency, a reliable connection interface, sufficient environmental stability, and long fatigue life (∼10,000 cyclic loadings). An optimized scanning readout approach was applied to read the signals of the sensor array with an error of less than 1%. Additionally, the spatial strain distribution of the knee movement captured by the sensor array demonstrated its advantages in capturing human dynamic motions. This method paves the way for the design and fabrication of stretchable-fabric-based sensor arrays and circuits that can be applied to intelligent wearable systems.

Non-Destructive Thin Film Thickness Measurement based on Coplanar Capacitive Sensor and Printed Circuit Board Platform

This paper presents a compact design of a coplanar capacitive sensor based on a printed circuit board (PCB) to apply in non-contact and non-destructive thin film thickness measurement. The capacitive sensor design is structured by two coplanar capacitors, including a reference coplanar capacitor and a sensing coplanar capacitor. Using this structure, the thin film thickness could be estimated through the imbalance voltage produced between the two signals from the reference capacitor and sensing capacitor. The size of the proposed sensor is 9.99 × 9.99 mm and the capacitor electrodes structured by shapes of spiral, interdigital, and round are studied and optimized. Those electrode structures have been modelled and simulated and the simulation results reveal that the spiral structure gives the best performance. The experiment was conducted using plastic thin films with thickness ranging from 10 to 230 µm and dielectric constants ranging from 1.375 to 3.19 to investigate the working principle of the sensor. Experiment results show the approximate linearity of the output voltage corresponding to the various thickness at measurement range from 0 to 90 µm. The sensitivity of the sensor is 13.5 and 29 mV/µm corresponding to the 1.375 and 3.19 dielectric constants of the thin films, respectively. The proposed coplanar capacitive sensor is fabricated based on the PCB platform and shows good performance with a minimum cost. The experiment results demonstrate that this sensor has a high potential to be applied in several biomedical and industrial thin film thickness measurement applications.

A novel switched-capacitor based multilevel voltage boost inverter for EV interface

ABSTRACT Lithium cells are connected in parallel and series to meet the current and voltage requirements in Electric vehicles (EV). Voltage and charge equaliser techniques are employed to protect the lithium cells. These equalisation circuits introduce the loss to the circuit, and the battery pack gets disconnected if any cell is faulty. Switched-capacitor converters have become an alternative to meet the voltage requirement. This article presents a voltage boost multilevel inverter configuration for electric vehicle applications. The proposed MLI features an inherent capacitor self-balancing capability and generates an output with a nine-level range. Algorithms for capacitor voltage balancing or additional sensor circuits are not required because of intrinsic self-balancing. For generating output levels, capacitors with a voltage source with an appropriate charging/discharging pattern are used. The proposed inverter doubles the output voltage for nine levels. A comparison of components, such as the number of semiconductors, diodes, gate driver circuits, and capacitors; system parameters such as voltage gain, blocking voltage, and TSV, is presented to demonstrate the advantages of the proposed MLI over recently developed topologies.

An RF Power Amplifier Integrated With the Self-Health Monitor Sensor and Multisource Energy Harvesting Circuit

An RF Power Amplifier Integrated With the Self-Health Monitor Sensor and Multisource Energy Harvesting Circuit

High-Temperature and High-Electron Mobility Metal-Oxide-Semiconductor Field-Effect Transistors Based on N-Type Diamond.

Diamond holds the highest figure-of-merits among all the known semiconductors for next-generation electronic devices far beyond the performance of conventional semiconductor silicon. To realize diamond integrated circuits, both n- and p-channel conductivity are required for the development of diamond complementary metal-oxide-semiconductor (CMOS) devices, as those established for semiconductor silicon. However, diamond CMOS has never been achieved due to the challenge in n-type channel MOS field-effect transistors (MOSFETs). Here, electronic-grade phosphorus-doped n-type diamond epilayer with an atomically flat surface based on step-flow nucleation mode is fabricated. Consequently, n-channel diamond MOSFETs are demonstrated. The n-type diamond MOSFETs exhibit a high field-effect mobility around 150cm2V-1 s-1 at 573K, which is the highest among all the n-channel MOSFETs based on wide-bandgap semiconductors. This work enables the development of energy-efficient and high-reliability CMOS integrated circuits for high-power electronics, integrated spintronics, and extreme sensors under harsh environments.

Shunt capacitor array shock wave position sensor

The position of the shock wave front under an impact load can reveal many material properties. A design of a shunt capacitive shock wave position sensor has been investigated in this work, utilizing a series of electric probes connected to the shunt capacitor array to measure the moment when the shock wave front reaches a specific point on the sample, which can be used to determine the shock wave front's evolution law. Using the Simulink module in MATLAB software, a sensor circuit model was designed and simulated, and the influence of various conditions on the output signal's falling edge relaxation times were investigated. The results indicate that the relaxation times initially increase, then gradually flatten out, after that, when electrical probes are progressively triggered, the relaxation times will increase again. The relaxation time increase with the rising capacitance, self-inductance coefficient, and voltage drop, and it decrease with increasing coupling coefficient. In addition, it initially decreases and then increase as the initial output voltage increases. Comparing the output signals of the traditional series resistance shock wave position sensor under the same general parameters, it reveals that the voltage falling edge relaxation times for each stage of the sensor are in the order of 10−10 s magnitude, much smaller than the 10−8 s magnitude of the latter, indicating higher measurement accuracy for the sensor. In this work, it also provides a reliable theoretical basis for selecting circuit parameters of the shunt capacitor shock position sensor in experiments by simulation.

Two Proposals of a Simple Analog Conditioning Circuit for Remote Resistive Sensors with a Three-Wire Connection.

This article proposes and experimentally characterizes two implementations of a novel front-end circuit for three-wire connected resistive sensors with a wire-resistance compensation. The first implementation relies on two twin diodes, whereas the second on a switch; in both cases, those devices are non-remote (i.e., they are placed at the circuit end). The two circuit proposals have a square-wave input excitation so that a constant current with the two polarities is alternatively generated. Then, depending on that polarity, the current goes through either the sensor and the wire parasitic resistances or just the parasitic resistances. This generates a square-wave bipolar output signal whose average value, which is obtained by a low-pass filter, is proportional to the sensor resistance and only depends on the mismatch between two of the three wire resistances involved. Experimental tests applied to resistances related to a Pt100 thermal sensor show a remarkable linearity. For example, the switch-based front-end circuit offers a non-linearity error lower than 0.01% full-scale span, and this is practically insensitive to both the presence and the mismatch between the wire resistances.

An Isolation Amplifier-Based Front-End Circuit for Grounded Capacitive Sensors

An Isolation Amplifier-Based Front-End Circuit for Grounded Capacitive Sensors

A fully differential analog read-out circuit for differential capacitive sensors

A fully differential analog read-out circuit for differential capacitive sensors

3D Position Tracking Using On-Chip Magnetic Sensing in Image-Guided Navigation Bronchoscopy.

This paper presents a compact and low-cost on-chip sensor and readout circuit. The sensor achieves high-resolution 5-degrees-of-freedom (DoF) tracking (x, y, z, yaw, and pitch). With the help of an external wire wound sensor, it can also achieve high-resolution 6-degrees-of-freedom (DoF) tracking (x, y, z, yaw, pitch, and roll angles). The sensor uses low-frequency magnetic fields to detect the position and orientation of instruments, providing a viable alternative to using X-rays in image-guided surgery. To measure the local magnetic field, a highly miniaturised on-chip magnetic sensor capable of sensing the magnetic field has been developed incorporating an on-chip magnetic sensor coil, analog-front end, continuous-time ∆Σ analog-to-digital converter (ADC), LVDS transmitter, bandgap reference, and voltage regulator. The microchip is fabricated using 65 nm CMOS technology and occupies an area of 1.06 mm 2, the smallest reported among similar designs to the best of our knowledge. The 5-DoF system accurately navigates with a precision of 1.1 mm within the volume-of-interest (VOI) of 15 ×15 ×15 cm 3. The 6-DoF system achieves a navigation accuracy of 0.8 mm and an angular error of 1.1 degrees in the same VOI. These results were obtained at a 20 Hz update rate in benchtop characterisation. The prototype sensor demonstrates accurate position tracking in real-life pre-clinical in-vivo settings within the porcine lung of a live swine, achieving a reported worst-case registration accuracy of 5.8 mm.

Lifetime Optimization of Optical Sensing System With Highly Reliable a-Si:H TFT-Based Optical Sensor and Driver Circuit in Large AMLCDs

Lifetime Optimization of Optical Sensing System With Highly Reliable a-Si:H TFT-Based Optical Sensor and Driver Circuit in Large AMLCDs