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Piezo-electric sensors have found widespread application today due to their ability to provide an interface between the mechanical and electronic world. For humans, in order to interact with these materials, we require an electronic interface. This paper describes one of the possible interfaces, which includes a charge amplifier cascaded with a filter circuit to obtain the frequency response. A novel circuitry consisting of a rectifier and comparator is used to identify the activated channels of the array of piezoelectric sensor. This signal conditioning circuit makes use of active devices such as op amps and nonlinear devices such as diodes along with passive components. The novel circuitry is designed for 2 channels, and demonstrates the logic of selection of these based on the signal parameters. This concept can be extended to any number of channels.

In-line measurement of the mass flow rate of solids in pneumatic conveying pipelines is essential for the efficient and optimized operation of many industrial processes. This paper presents a comparative study of using induced and transferred charges from non-intrusive electrodes exposed to the particle flow for mass flow rate measurement. A novel signal conditioning circuit, which consists of a current sense amplifier and a charge amplifier, is designed to convert the induced and transferred charges into two separate voltage signals. Empirical measurement models that relate the particle velocity, the root-mean-square (r.m.s) magnitude of the induced charge signal and the slope of the transferred charge signal to the mass flow rate are proposed. Experiments were undertaken using electrodes of different widths and under different mass flow rate and particle velocity conditions. Results obtained show that both the r.m.s magnitude of the induced charge signal and the slope of the transferred charge signal increase with the mass flow rate and the velocity of particles. In general, the measurement results using the induced and transferred charges from either the narrow or the wide electrode are similar. However, the method based on the transferred charge is less reliable due to confined sensing area and electrode charging by particles adhered to the electrode surface.

A charge amplifier with noise peaking suppression and gain drop compensation is proposed. By utilizing the proposed Quasi-Miller RC network, the noise peaking is suppressed and gain drop is compensated, which alleviates the design trade-off between charge gain and output root-mean-square (RMS) noise, therefore obtains an improved sensitivity. Meanwhile, the Quasi-Miller RC network permits the charge amplifier to support ultra-low frequency operation without using a huge resistor, which is normally required by the charge amplifier. The fabricated charge amplifier demonstrates an input-referred RMS noise charge of 909 aC, a charge gain of 10.2 V/pC and a 3-dB bandwidth from 80 Hz to 38 MHz. Low noise and high charge gain are obtained simultaneously. Meanwhile, extremely low cut-off frequency is also obtained, which is beneficial to maintain the signal integrity.

In this paper, a novel piezoelectric sensor is presented for patient's breath monitoring applications. Breath rate monitoring is important especially for the new coronavirus patients. In this work, a piezoelectric sensor is designed in the form of a vertex-attached triangular beam made of Polyvinylidene fluoride (PVDF) and Polydimethylsiloxane (PDMS). It exploits chest displacement to distinguish breathing vibrations. The device shape and dimensions have been designed for low frequency operation. The output respiration signal is amplified using a low power charge amplifier circuit. The sensor can be placed in a vest and fastened as a belt, or be attached to the chest by a tape. A low pass filter is used to eliminate the noise from the environment and body movement. Among the most important features are high accuracy, low resonance frequency to distinguish chest movement, low weight, low cost, portability, and reliability. Simulation of the designed sensor using COMSOL shows output voltage of 1 V at breathing frequency of 0.2 Hz.

With the advanced technologies such as 5 G network and internet of things (IoT), there are incredibly increasing sensors and corresponding applications emerging to benefit our daily lives. However, the power supplies for countless sensors become a serious issue to suppress further expansion of IoT. In this work, a self-powered triboelectric sensor (CN-STS) made of electrospun composite nanofibers is developed towards smart traffic monitoring and management. To meet the requirements of fast-response and high sensitivity for the smart traffic management, transferred charge density is adopted as sensing signals compared to voltage / current outputs for it can perfectly record the subtle differences and suitable for dynamic traffic monitoring. Carbon nanotube is further doped into PVDF nanofibers to improve the electrical output performance and pressure sensitivity. A relatively high sensitivity of 0.0406 μ Cm-2kPa-1 at low pressure range (0 to 75 kPa) and a sensitivity of 0.0032 μ Cm-2kPa-1 at higher pressure range (75 to 425 kPa) can be achieved by the CN-STS, indicating that the CN-STS is more sensitive at low pressure range. Moreover, by connecting to cloud IoT services, the functions of traffic flow management, overlapping and speeding vehicle capturing, and plate number recognition are realized by the CN-STS arrays with a compensation circuit. A charge amplifier is utilized in power management to process the charge input signals for better distinguishing the signals from none-vehicles and stabilize the volage output for further reading by the A/D convertor build in Raspberry Pi. The engineered self-powered triboelectric sensors not only open a new potential area for triboelectric nanogenerators but also significantly popularize the IoT industry.

In this study, we successfully developed a high signal-to-noise ratio (SNR) rangefinder based on a piezoelectric micromachined ultrasonic transducer (pMUT). A c-axis-oriented Pb(Mn1/3,Nb2/3)O3-Pb(Zr,Ti)O3 (PMnN-PZT) epitaxial thin film was employed as a piezoelectric transducer considering its outstanding figures-of-merit for SNR, due to the high piezoelectric coefficient and small relative permittivity (typical values: e31,f = −14C/m2, er = 200–300). The pMUTs was based on an epitaxial PMnN-PZT/Si diaphragm structure and prototyped from a SOI substrate; its rangefinding ability was evaluated with a pair of devices, specifically, transmitter and receiver, respectively. As a result, the maximum range was estimated to be over 2 m at a low actuating voltage of 1 Vp-p, when 12 dB was set as the threshold SNR. The energy consumption of the transmitter was as small as ∼5 nJ for the generation of a 50-cycle ultrasonic burst. The noise analysis of the receiver’s charge amplifier circuit indicated that this system could be improved by the optimization of bandwidth and by eliminating external noise. We believe that this high performance pMUT rangefinder will be utilized in various applications of consumer electronics or as an alternative to the bulk piezoelectric ceramic rangefinder in the near future.

Integrators are an important functional module of several filters, PID controllers and automated systems. Designing these integrators in fractional domain enhance their operations and make the responses highly precise and accurate. This paper presents a Fractional Order Current Integrator using second generation current conveyor as the active block, and fractional capacitor as a grounded fractance. Analog realization of this fractance comprises of resistances and capacitances arranged in parallel RC ladder topology. The motivation behind this work is that more accurate and stable fractional integrator with fewer passive elements, for lower bias voltage and high dynamic range, can be designed and implemented. Integrators of fractional orders from 0.1 to 0.9 are simulated using TSMC 0.25 µm technology parameters. The transient and frequency responses obtained in Mentor Graphics are in close conformity with the theoretical values of magnitude and phase. Robustness of the proposed model is verified by performing Monte Carlo analysis in time and in frequency domain. Comparisons of fractional order current integrators with existing analog fractance models have also been included to further validate the work presented in the paper.

In this paper, we investigate the responsivities and output voltage noise power spectral densities of magnetoelectric (ME) laminate sensors, consisting of length magnetized Terfenol-D alloys and transverse/width poled Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMNT) crystals (i.e. L-T mode and L-W mode respectively), which are directly integrated with custom-build low noise charge amplifier circuits. Both the theoretical analyses and experimental results prove that the L-W mode sensor with the optimized polarized direction of the PMNT plate possesses lower magnetic detection limit at the interested high frequency range of 10 kHz≤ f ≤50 kHz. The equivalent magnetic noise ( EMN ) of the L-W mode sensor is 0.78 pT/Hz 1/2 at 30 kHz, which is about 1.7 times lower than the 1.35 pT/Hz 1/2 for conventional L-T mode sensor. Furthermore, an effective method of using operational amplifiers with low equivalent input noise voltage and employing ME laminate composites with high voltage coefficient to reduce the EMN s of the ME laminate sensors at high frequency range has been established.

International audience; Next generation pixel chips at the High-Luminosity (HL) LHC will be exposed to extremely high levels of radiation and particle rates. In the so-called Phase II upgrade, ATLAS and CMS will need a completely new tracker detector, complying with the very demanding operating conditions and the delivered luminosity (up to 5×10 34 cm −2 s −1 in the next decade). This work is concerned with the design of a synchronous analog processor with zero dead time developed in a 65 nm CMOS technology, conceived for pixel detectors at the HL-LHC experiment upgrades. It includes a low noise, fast charge sensitive amplifier featuring a detector leakage compensation circuit, and a compact, single ended comparator that guarantees very good performance in terms of channel-to-channel dispersion of threshold without needing any pixel-level trimming. A flash ADC is exploited for digital conversion immediately after the charge amplifier. A thorough discussion on the design of the charge amplifier and the comparator is provided along with an exhaustive set of simulation results.

A miniaturized wireless accelerometer using a piezoelectric micro sensing element is designed, theoretically analyzed, and demonstrated for remote mechanical vibration monitoring. The micro sensing element comprises a micromachined monolithic silicon seismic mass and multiple silicon beams coated with in-plane polarized (Pb, La)(Zr, Ti)O3 (PLZT) ferroelectric thin film. A low profile compact package is obtained for accommodating all the micro sensing element, charge amplifier and signal processing circuits, radio frequency module, and battery. The electrical output linearly proportional to the vibration acceleration is amplified, digitalized and transmitted to a remote base unit through radio frequency communication. The effects of the device package on the dynamic response of the wireless piezoelectric accelerometer including shielding of ambient interference are investigated.

This paper describes a self-compensating system for fixed pattern noise reduction (FPNR) of focal plane arrays (FPA) of infrared (IR) bolometer detectors. The proposed system used a ΔΣ modulator of first order which operates as non-saturating current integrator. The method also suppressed the self-heating effect as well as the effect of resistance non-uniformity across the FPA. The read-out circuit (ROIC) was designed in ONSemi I2T100 technology considering the matching and noise effects and fabricated using EUROPRACTICE service. Its verification was made on the test printed circuit board (PCB) with the variable resistors. These resistors were changed to emulate the real bolometer behavior due to IR radiation.

Area-changed capacitive displacement transducers have been widely applied in micro-electro-mechanical-system (MEMS) sensors such as sandwich-type MEMS accelerometers to detect in-plane displacement with a high sensitivity. The cross-axis disturbance could result in out-of-plane displacement of the proof mass, which brings a gap variation of sensing capacitor electrodes and lead to an undesirable variation of the accelerometer’s scale factor. In order to solve this problem, this paper presents a novel method to improve out-of-plane robustness of an Area-changed capacitive displacement transducer in a MEMS accelerometer. An on-chip capacitor, sensitive to the out-of-plane displacement of proof mass, was integrated as the feedback capacitor of the charge amplifier. Thus, the influence of the out-of-plane displacement on the scale factor caused by cross-axis disturbance is compensated. The method was verified by theoretical calculation, simulation and experiments. The results indicated that the cross-sensitivity of the MEMS accelerometer with an on-chip feedback capacitor was less than 1/3 of that with off-chip feedback capacitor when acceleration was applied on the out-of-plane direction. Besides, the noise floor of the accelerometer maintained at 60 ng/√Hz regardless of the on-chip or off-chip feedback capacitors.

A fabricated amperometric sensor readout chip for interfacing with multiple electrochemical cells is presented. The chip incorporates a current integrator which can be used for charge determination and current accumulation for drift compensation. It also has a programmable redox potential generator. The front-end consists of a PMOS source input driven by a high gain OTA. It achieves very low input impedance and consequently, a wide current sensing range. The circuit utilizes pass elements acting as sensor enable for minimizing cross-talk. The current integrator utilizes a CCII+ with pre-settable gain. This is used to compensate for the sensor drift and degrading signal-noise-ratio whenever its enzyme is expended. The readout circuit was fabricated using TSMC 0.35 ​ ​μm technology. Digital interface was implemented onto an FPGA using the Altera 90 ​nm Cyclone II DE2 board. The system was tested using commercial two-electrode glucose and uric acid sensors, and a three-electrode uric acid biosensor. Experimentation confirms the functionality of the system using known analyte concentrations.

Estimation of state-of-charge (SOC) is a key criterion to evaluate the battery management system (BMS). Due to the flat open-circuit voltage (OCV)–SOC curve of LiFePO 4 batteries, it is a great challenge to estimate the SOC accurately. Here we present a dual-circuit state observer for SOC estimation of LiFePO 4 batteries. It is a combination of an open loop based current integrator and a proportional-integral (PI) based state observer. We also employed an easy but practical drifting current corrector to restrain the influence of the drifting current. The experiment results show that error of the estimated SOC is less than 2.5% by the proposed method when the initial SOC is unknown. We proved that with no matrix operations, the proposed method is lighted-weighted and high efficient, which is suitable for embedded systems.

A wide input range, compliant with electrochemical amperometric and voltammetric sensors analog-front-end (AFE) integrated circuit (IC) is proposed. The AFE employs current integrator (CI) and trans-impedance amplifier (TIA) to deal with the input current in the order of nA and µA separately, achieving the advantage of high dynamic range and high resolution. Input voltage is converted to current through a series of precise resistances, and detected by CI or TIA, which making the input voltage range is not limited by the power supply. An incremental sigma-delta ADC is employed to digitize the transferring signal, reducing the complexity and power dissipation. Compared to other alternatives, the AFE could handle current and voltage signals simultaneously, and input voltage range is not limited by power supply, showing high dynamic range and resolution. The AFE IC is fabricated in 0.18µm 1P5M mixed-signal CMOS process, occupies an area of 3.2mmi?2mm, the readout circuit has a dynamic range of 120dB, consumes 4.2mA. The AFE IC present in this manuscript employs dual-path, current integrator (CI) and trans-impedance amplifier (TIA), to deal with the input current in the order of nA and µA separately, achieving the advantage of high dynamic range and high resolution.The AFE IC can be compliant with both electrochemical amperometric and voltammetric sensors, instead of traditional instrument amplifier, a voltage-to-current circuit is adopted to convert an input voltage to a current, making the input voltage range is not limited by the power supply.Instead of a traditional sigma-delta ADC, a incremental sigma-delta ADC is employed to digitize the transferring signal, reducing the complexity and power dissipation, providing the feature of one-to-one mapping between input and output.

The need of performing high resolution fast neutron spectroscopy in a very harsh environment like that of the Radial Neutron Camera (RNC) of ITER, requires to develop new detectors and methodologies. Diamond detectors have been proved to be excellent candidates but the electronics needs a substantial improvement. Because of the high radiation level and the temperatures expected near the detector positions in the RNC, the electronics must be placed several meters away. A novel Fast Charge Amplifier (FCA) was developed that, connected to a diamond detector using several tens of meters of low capacitance coaxial cable, is able to produce fast output signals suitable to be processed by digital electronics. These fast output signals allow to operate at high count rates avoiding pile-up problems. This novel amplifier connected to a digitizer is here tested in the neutron energy range from 5 to 20.5 MeV using the mono-energetic neutrons produced by the Van de Graaff (VdG) accelerator of the EC-JRC-IRMM and by the PTB cyclotron. From the measurements the experimental response functions of the diamond detector at different neutron energies were obtained. The shape of the response functions have been compared with that predicted with a routine which was implemented for the Monte Carlo code MCNPX with the scope to validate the calculations versus the experimental data. The goal is to develop a tool which allows to calculate the diamond detector response functions also in term of absolute efficiency. This methodology along with the ability to measure at high reaction rates and the insensitivity to radiation damage launches the system described in this paper as a promising method for neutron spectrometry in the RNC of ITER. © 2014 Elsevier B.V.

In this paper, we propose an energy-efficient 13-bit capacitive sensor interface circuit. The proposed design fully relies on successive approximation algorithm, which eliminates the need for oversampling and digital decimation filtering, and thus low-power consumption is achieved. The proposed architecture employs a charge amplifier stage to acheive parasitic insensitive operation and fine absolute resolution. Moreover, the output code is not affected by offset voltages or charge injection. The successive approximation algorithm is implemented in the capacitance-domain using a coarse-fine programmable capacitor array, which allows digitizing wide capacitance range in compact area. Analysis for the maximum achievable resolution due to mismatch is provided. The proposed design is insensitive to any reference voltage or current which translates to low temperature sensitivity. The operation of a prototype fabricated in a standard CMOS technology is experimentally verified using both on-chip and off-chip capacitive sensors. Compared to similar prior work, the fabricated prototype achieves and excellent energy efficiency of 34 pJ/step.

This paper presents a device for managing the inertial loads on photoreticles of lithography scanners. At high scan accelerations, the reticle inertial load can approach the clamp force limit. As a result, nanometer-level presliding slip can occur. Reticle slip is one limitation on increasing the throughput of the lithography scanners. In this paper, we present a reticle assist device which can eliminate reticle slip by compensating better than 95% of the inertial loads when tested in a bench-top tester. The reticle assist device consists of a coarse approach mechanism, for accommodating reticle load/unload, and a piezoelectric stack for fine actuation. The device utilizes a sensorless control system design. The control system uses a self-sensing contact detection method, which is inspired by self-sensing scanning probe microscopy, to find the reticle edge. It also uses a charge amplifier with a novel hybrid hysteresis compensation technique to linearly control the piezoelectric actuator extension, without the need for closed-loop position control. When tested with a replicated force profile with 60 N peak force and 6400 N/s force rate, the assist device compensated better than 95% of the inertial load.

We have successfully demonstrated the fabrication of piezoelectric rubber films and their applications in heartbeat sensing and human energy harvesting. To realize the desired stretchability and electromechanical sensitivity, cellular polydimethylsiloxane (PDMS) structures with micrometer-sized voids are internally implanted with bipolar charges, which function as dipoles and respond promptly to diverse electromechanical stimuli. The resulting composite structures behave like rubber (with an elastic modulus about 300 kPa) and show strong piezoelectricity (with a piezoelectric coefficient d33 higher than 1500 pC/N). In the prototype demonstration, an autonomous heartbeat monitoring system utilizing stacked piezoelectric PDMS films is demonstrated. While integrated with a 12-μA h solid-state energy storage device and a 552-nW nano-power charge amplifier, the energy harvested from human body is stored and employed to monitor heartbeat. With a working area of 10 cm2 and a compressive load of 10 kg, it is estimated that a charge of 0.1 μC/cycle can be collected using a single-layered piezoelectric rubber film. Furthermore, multiple layers can be stacked and connected in parallel to magnify the charge output. As such, the demonstrated piezoelectric rubber films, which function as both stretchable energy harvesters and highly-sensitive impact sensors, possess a great potential for the realization of wearable and implantable human physiological monitoring systems.

This work moves toward the state-of-the-art for the interfaces usually employed for three-axes micromachined gyroscopes. Several architectures based on multiplexing schemes in order to extremely simplify the analog front-end which can be based on a single charge amplifier are analyzed and compared. This paper presents a novel solution that experiments an innovative readout technique based on a special analog-CDMA (Code Division Multiplexing Access); this architecture can reach a considerable reduction of the analog front-end with reference to other multiplexing schemes. Many family codes have been considered in order to find the best trade-off between performance and complexity. System-level simulations prove the effectiveness of this technique in processing all the required signals. Finally, a case study is analyzed: a comparison with the SD740 micro-machined integrated inertial module with a tri-axial gyroscope by SensorDynamics AG is provided.

Freestanding cantilevers have been fabricated by screen printing sacrificial and structural layers onto a standard polyester cotton fabric. By screen printing additional conductive and piezoelectric layers on to the cantilever it is possible to detect its displacement due to the movement of the underlying fabric. This type of freestanding structure cannot currently be fabricated using more conventional smart fabric manufacturing processes (e.g. weaving and knitting). Compared to such processes, screen printing offers the advantages of geometric design flexibility and the ability to simultaneously print multiple devices of the same or different designs. Furthermore, an expanding range of active inks exists from the printed electronics industry which can potentially be applied to create many types of smart fabric. To demonstrate the potential of this technology, a six-layer structure design has been printed onto fabric using a sacrificial material underneath the cantilever. The sacrificial layer is subsequently removed at 160 °C for 30 min to achieve a freestanding cantilever above the fabric. The devices have been worn on a human forearm and connected to a charge amplifier provided an example of simple motion detection.

This paper presents a novel approach for precisely controlling the motion of a piezo actuator embedded in a mechanical stage without using a displacement sensor. A piezo actuator has a high displacement resolution, but the positioning performance is degraded by hysteresis between the applied voltage and resultant displacement. However, an electromechanical model of a piezo actuator suggests that the charge flowing in the actuator is directly related to the dynamic response of the piezo displacement. Therefore, this study directly measured the charge stored in a piezo actuator, and achieved dynamic reference tracking of the actuator's displacement by regulating the charge flowing through the actuator to follow a predefined trajectory. This novel approach requires neither specially designed charge amplifier circuits nor implementation of an inverse hysteresis model. The complete model identification and the digital controller design procedure for a piezo-driven mechanical stage are presented. The charge feedback controller is designed according to the dynamic characteristics of both the actuator and the stage, so that instability is minimized relative to using a charge amplifier. The experimental results confirm satisfactory tracking performance, and reveal the influence of model uncertainties on the system performance.

Piezoelectric tube actuators are widely used in nanopositioning applications, especially in scanning probe microscopes to manipulate matter at nanometer scale. Accurate displacement control of these actuators is critical, and in order to avoid the expense and practical limits of highly accurate displacement sensors, sensorless control has recently attracted much attention. As the electrical charge on these actuators is an accurate indicator of their displacement exhibiting almost no hysteresis over a wide range of frequencies, it suggests that charge measurement can replace displacement sensors. However, charge-based methods suffer from poor low frequency response and voltage drop across the sensing capacitor. In this paper, a displacement estimator is presented that complements a digitally implemented charge amplifier with an artificial neural network (ANN) designed and trained to estimate the piezoelectric tube's displacement using the piezoelectric voltage at low frequencies of excitation where the charge methods fail. A complementary filter combines the grounded-load digital charge amplifier (GDCDE) and the ANN to estimate displacement over a wide bandwidth and to overcome drift. The discrepancy between the desired and estimated displacement is fed back to the piezoelectric actuator using proportional control. Experimental results highlight the effectiveness of the proposed design.

In this paper, we present a quasi-static charge amplifier method to detect the extremely low frequency response of Metglas/Pb(Mg 1/3 Nb 2/3 )O 3 –PbTiO 3 magnetoelectric (ME) laminated composites. Using this technique, ME effect can be detected at f −2 Hz, and ME charge coefficients show good stability over wide frequency range from 10 mHz to 1 kHz. Thus, it allows us to develop a quasi-static magnetic sensor based on ME composites which can work at frequencies as low as 10 mHz, with equivalent magnetic noise floors of about 3 nT/√Hz.

Grain losses are unavoidable during harvesting. In order to improve the efficiency and reduce grain losses, the major structural and operational parameters of combine harvesters need to be adjusted accordingly. So, it is important to develop a sensor which can monitor the grain losses real-time. A sensor using piezoelectric polyvinylidene fluoride (PVDF) film as sensitive material for monitoring grain losses of combine harvesters is described. A floating raft damping structure was used to construct the sensor to suppress the influence of vibrations. Based on a dynamic analysis of sensor model, response properties of the sensor under working conditions were calculated. The results indicated that the amplitude and frequency of vibration interference were both decreased by optimising the isolators. A signal processing circuit composed of charge amplifier, high-pass filter, absolute value amplifier, envelope detector and voltage comparator in series was designed to detect grain impact signal. A square wave voltage signal was produced while grain impact was detected, and the mean time width was

The High-Speed Image Pre-Processor with Oversampling (HIPPO) is a prototype image sensor readout integrated circuit designed for both high performance and enhanced flexibility. HIPPO's initial target application is the instrumentation of bufferless, column-parallel, soft x-ray Charge-Coupled Device (CCD) image sensors operating at column rates up to 10 MHz, enabling 10,000 frames-per-second (fps) video rates. HIPPO's architecture is flexible and allows design tradeoffs between speed, accuracy, and area. This architectural flexibility will enable the fast development of related image sensor and particle detector readout ICs based on HIPPO technology. HIPPO contains 16 channels, each comprising a charge amplifier, a dual-slope correlated double sampler, a sample-and-hold, a multiplexed 12b, 80 MS/s pipelined ADC (one ADC for every 4 channels), and a 480 Mb/s output serializer. HIPPO achieves 35 e-read noise at 10,000 fps for a 1 Mpixel sensor, improving to 24 e-at 5000 fps. HIPPO's charge-domain input obviates the source follower amplifier used in most CCDs and enables the implementation of a fully column-parallel CCD architecture. HIPPO was specifically designed to be flexible in both the sequencing of its operations and in its ability to accommodate input rates potentially varying over an order of magnitude.

Based on laboratory experimental results obtained with an axial threshing test-rig with tangential feeding, cumulative distribution functions of separated grain in axial and radial directions of threshing rotor were built. Based on the analysis of the relationship between grain separation loss and grain separation flux in an area under the concave, an indirect grain separation loss monitoring method is presented in this paper. Piezo-electric polyvinylidene fluoride (PVDF) film was selected as sensitive material to design a grain flux sensor. While grain and material-other-than-grain (MOG) separated in the monitoring area impact on piezo-electric PVDF films, different electric charges are generated. After signal progressing with a charge amplifier, frequency discrimination and wave shaping, the number of grain can be counted by a microcontroller (MCU) and the grain separation loss of combine harvester can be measured in real-time. Field test results indicated that the measurement errors of grain separation loss recorded by the monitoring system relative to the loss checked manually were less than 12%.

The output characteristics of the basic current feedback operational amplifier (CFOA) in the linear region, on open-loop, would not appear to have been treated in the literature. This is possibly because it is not straightforward to determine, the problem being that the output saturates without the closed-loop connection. This paper considers a theoretical discussion that explains the results of simulation.

An fF-level capacitive sensor, intended for pL liquid measurements, has been fabricated with MEMS technology and successfully characterized. The sensor measures liquid level variations in a microfluidic channel. The sensor’s capacitance varies from 1.5 fF (channel empty) to 12.8fF (channel filled with 63 pL of water). To reliably detect such small capacitance changes, a low noise measurement system, based on a lock-in amplifier, was implemented. The measured sensitivity of the system is 14.1 mV/fF, and the capacitance detection limit is 0.057 aF/Hz 1/2 , which corresponds to a volumetric resolution of about 0.22 fL/Hz 1/2 .

Generation of extensional waves in a linearly elastic bar by means of a pair of attached piezoelectric actuators driven by a power amplifier with output current constraints is studied theoretically and experimentally. In addition to its current constraints, the amplifier is characterized by its DC voltage gain and 3 dB cut-off frequency. On the basis of 1D wave propagation, time-domain relations are established for the nonlinear dependence of the output voltage and current of the amplifier, and of the strain associated with the waves generated, on the input voltage. It is found that the amplifier model used allows prediction of the main features of this dependence. Nonlinear operation due to constrained output current may occur even at a low input voltage if the rate of change of this voltage is excessive. Consideration of this phenomenon is important in, e.g., control applications.

This paper presents a new arrangement for the indicating measurement system utilized in the study of internal combustion engines. In this experimental configuration, the current polarized by a piezoelectric pressure transducer is converted into an analog signal proportional to the cylinder pressure variation rate, which constitutes the primary information for combustion heat release analysis. The proposed technique reduces the uncertainty in the pressure derivative data, providing more accurate heat release results than those obtained with the traditional transducer signal conditioning procedure, which requires the numerical derivation of in-cylinder pressure data supplied by a charge amplifier.

We present a prototype, modular, autonomous fluidic sensor system that will be capable of long-term in the field use. Modularity extends from the ability of the system to support different sensing modes (gas or liquid), and autonomy extends from it being self-contained and operating independently. We demonstrate the first use of a custom CMOS integrated circuit that has a photodiode and charge amplifier for sensing, and combine this with a microcontroller to allow for autonomous operation in a very small package. The sensor portion can respond to color change in a liquid or intensity change from a luminescent chemical sensor. Ultimately, multiple sensors can be used at once to determine the concentration of pollutants.

Piezoelectric sensor (PZT) based structural health monitoring (SHM) methods can efficiently estimate the health condition of aircraft structures. To monitor large-scale structures, dense PZT arrays are usually needed. How to scan different PZT actuator–sensor channels in the PZT array to achieve a real time and stable SHM task is an important issue in the application of these methods. In this paper, an integrated multi-channel PZT array scanning system (ISS) is developed for the purpose of SHM. A type of gain programmable charge amplifier and a low crosstalk scanning module are discussed. An integrated software system which is based on the LabVIEW software platform is developed to manage the hardware, and perform signal processing and damage estimation. To validate the functions of this system, an evaluation is performed on a carbon fiber composite wing box of an unmanned aerial vehicle (UAV). The application results show the promising performance of this system.

The paper covers a pure analog amplifier design favorable to drive capacitive solid state actuators such as piezoelectric actuators. The research in this field is prompted by the introduction of a new piezoelectric motor (piezoelectric actuator drive – PAD) which employs piezoelectric multilayer actuators, offering mechanical output power of up to 20 W. Due to their static and continuous operation, the actuators of the motor need to be supplied by high-quality, low-frequency, high-voltage, sinusoidal signals. The described circuit is an efficiency-improved class-B amplifier capable of recovering up to 50% of the charge stored in the actuator. The paper begins with a short overview of different amplifier types and their trade-off between signal quality, efficiency and circuit complexity. Starting with a description of the sources of power-loss in a basic class-B amplifier which drives a capacitive actuator, a hybrid design, combining the analog with a switched-mode amplifier, is discussed. The efficiency-improved class-B amplifier is then derived from the hybrid design. Finally, the amplifier is tested in an experiment together with the PAD.

The necessity of the converters compactness in many applications imposes the reduction of their different components size when it is possible. In this paper, a control method allowing the use of a small size dc-link capacitor for the cascade of voltage controlled-rectifier/inverter-motor drive system is proposed. This is achieved by adding the power balance equation in the system’s model and the application of an exact input/output feedback linearization technique in a way that the rectifier controller compensates any sudden change in the inverter load, which is here an induction motor. Since the exact input/output feedback linearization technique is sensitive to the uncertainties over system parameters, a robust control strategy based on sliding mode controller is proposed. By this approach, the dc-link voltage becomes almost insensitive to the load variations. As a result, the level of the dc-link voltage could be stabilized with a small size dc-link capacitor. Without any considerations of the RMS current stress on this dc-link capacitor, a calculation method of a minimum value of this capacitor based on its storage energy is proposed. All the investigations are shown by computer simulations and the performance of controlled system is verified by experimentation results.

The application of the capability of low-temperature poly-Si TFT circuits for high resolution X-ray active matrix sensor is explored. The integration of poly-Si TFT circuits on the glass enables an easy connection for the sensor array with fine pixel pitch. A novel charge sensitive amplifier circuit employing poly-Si TFTs is proposed for the readout system of the active matrix sensor. It can considerably increase the circuit’s immunity to the unavoidable threshold voltage variations of the poly-Si TFTs. The V TH mismatch effect of the TFTs, which results in the offset voltage of the charge amplifier, can also be suppressed by the proposed circuit. However, the noise arisen from the V TH mismatch can be even larger than that from the V TH variation after compensation. It reflects that, for higher bit digital X-ray image sensors, the mismatch effect of the devices must be properly taken into consideration.

The performance of a feedback-controlled piezoelectric tube scanner is limited by its inherent nonlinear properties such as hysteresis and creep, its mechanical resonance modes and its displacement sensor bandwidth and associated noise properties. Capacitive sensors have emerged as the displacement sensor of choice in piezoelectric tube scanners. Resolution of a capacitive sensor is largely determined by its bandwidth and noise density which is typically in the order of 20 pm/√Hz for a ±100 µm range. Consequently, to achieve sub-nanometer resolution, the sensor's bandwidth needs to be made small. Achieving satisfactory tracking performance using a low-bandwidth displacement sensor is a challenging task. To improve the bandwidth, the piezoelectric strain voltage induced in the electrode opposite to the actuating electrode is used as a secondary measurement. A two-sensor-based H∞ controller is designed and implemented on a prototype piezoelectric tube nanopositioning system. The tube is driven by a charge amplifier to reduce the hysteresis. Experimental results demonstrate a significant increase in the tracking bandwidth due to the use of the additional sensor.

A differential capacitance detection circuit aiming at detection of rotating angle in a novel levitation structure is presented. To ensure the low non-linearity and high resolution, noise analysis and non-linearity simulation are conducted. In the capacitance interface, an integral charge amplifier is adopted as a front end amplifier to reduce the parasitic capacitance caused by connecting wire. For the novel differential capacitance bridge with a coupling capacitor, the noise floor and non-linearity of the detection circuit are analyzed, and the results show that the detecting circuit is capable of realizing angle detection with high angular resolution and relative low non-linearity. With a specially designed printed circuit board, the circuit is simulated by PSpice. The practical experiment shows that the detection board can achieve angular resolution as high as 0.04° with a non-linearity error 2.3%.

A new procedure to obtain an online measurement of the beam intensity for charged particle accelerators, as well as the total charge deposited on a target, using a commercial beam profile monitor (BPM) is described in this paper. This procedure can be an alternative to the use of Faraday cups in experiments where their implementation is not feasible.

In this paper, we describe a method of carried charge signal conditioning associated to the pyroelectric effect: integration of the current in order to determine the temperature response measuring the power or the energy contained in optical radiations. The obtained results of investigation about the temperature response of a polyvinylidine fluoride (PVF2) pyroelectric detector to optical radiation using an appropriate electrical charge–current converter are reported. The experimental responses are compared to the ones obtained using a theoretical model which takes into account the wave propagation through the successive layers constituting the detector. A comparison of the responses obtained from two types of converters is presented and the independence of the pyroelectric detector from the topology of the conditioning circuit is also studied and demonstrated.

A high-sensitivity voltage-to-frequency converter (VFC) using an all-MOS voltage window comparator is presented in this work. The circuit is composed of one voltage-to-current converter, one charge and discharge circuit, and one all-MOS voltage window comparator. The input voltage is converted into a current which in turn triggers the charge and discharge circuit, where a built-in capacitor is driven. The voltage window comparator monitors the variated voltage on the capacitor and generate an oscillated output of which the vibration frequency is linearly dependent to the input voltage. In this way, the worst-case linear range of the output frequency of the proposed VFC is 0-55.40MHz verified by simulations given a 0-0.9V input range. The physical measurement of the proposed VFC shows a 0-52.95MHz output frequency given a 0-0.9V input range. The error in linearity is better than 8.5% while the power dissipation is merely 0.218mW.

This paper describes the design of a functional strain sensing module with large dynamic range (80 dB), DC to 10 kHz response, high resolution, and mini size for industrial applications, such as the rolling-element bearings research. The design of the MEMS capacitive strain sensor employs mechanical amplifications of package design and buckle beams as well as the linear differential comb capacitor. The sensor is interfaced with a low noise charge amplifier, mixer, and filter circuits to provide an analog output that demonstrated a resolution of 0.09 microstrains with a maximum range of ±1000 microstrains. The sensor and the electronic circuits, including a temperature sensor, can be integrated on a chip, and packaged as a small functional unit. Additional electronics were integrated with the interface circuit on the chip that provide A/D conversion, radio frequency power supply, and digital signal telemetry to a near-by control unit. Preliminary test results are compared with the design simulation.

We are developing CMOS monolithic active pixel sensors (MAPS) for High Energy Physics applications. We have successfully produced 3 test structures. They feature several different pixel types including: standard 3MOS, 4MOS allowing Correlated Double Sampling (CDS), charge amplifier pixels and a flexible APS (FAPS). The FAPS has a 10 deep pipeline on each pixel. This is specifically designed with the beam structure of the TESLA proposal for the Linear Collider in mind. Results of a laser test on our first device and source test results on two more recent test structures will be presented.

We describe the design of the analog portion of an electronics system to process signals from the photomultiplier tubes of the ATLAS Tile Calorimeter. The system has a 16-bit dynamic range and is capable of measuring energy depositions in a single calorimeter cell from ∼ 20 MeV to ∼ 1.3 TeV . In order to maintain the calorimeter calibration at the 1% level the system includes a charge injection circuit and a current integrator for use with a cesium source system and with the time-averaged currents produced by the LHC. The system also provides a signal for an analog adder which produces an energy sum for each calorimeter tower. Over 10,000 channels of this system have been constructed and delivered for use.

The silicon pixel detector of the PANDA experiment is characterized by both high track density and the absence of a hardware trigger signal, thus leading to a huge amount of data to be acquired and transmitted to the DAQ. In order to cope with such challenging requirements, an ASIC based custom solution for the electronic readout has been chosen. The ASIC, named ToPiX, will provide the time position of each hit and a measure of the charge released with the Time over Threshold (ToT) technique. A reduced scale prototype in a CMOS 0.13 μ m technology has been designed and tested. The prototype includes four columns made of 128 pixel cells, four columns of 32 cells and the end of column readout with a 32 cells deep FIFO for each double column. Each cell embeds a charge amplifier with constant current feedback capacitor discharge, a comparator with per cell adjustable threshold, 12-bits leading and trailing edge register for time and ToT measurement and an 8 bits configuration register. All the readout logic has been SEU-hardened by design using either Hamming encoding or triple modular redundancy. The chip has been tested both electrically via a test pulse input and connected to a detector in a beam test.

Recent development of next-generation medical devices, such as endoscopes and hearing aids, call for PZT (lead zirconate titanate oxide) thin-film sensors and actuators with thickness in the range of 1–30 μm to enhance actuation strength and sensor sensitivity. Currently, sol–gel derived PZT films often have thickness less than 0.2 μm per coating. Moreover, thermal stresses in the films limit the crack-free area to less than 1 mm2. This paper has four specific goals. The first goal is to demonstrate an improved sol–gel process using rapid thermal annealing and a diluted sealant coating. The resulting thickness can reach 2 μm in three coatings with a crack-free area as large as 5 mm ×5 mm . The second goal is to characterize piezoelectric properties of the fabricated PZT films experimentally. The resulting piezoelectric constant d33 is 120 pC/N and the dielectric constant ranges from 200 to 400. The third goal is to demonstrate the use of the PZT thin film as a calibrated sensor. The specimen is a silicon cantilever ( 30 mm ×7.5 mm ×0.4 mm ) with a PZT thin film ( 4 mm ×4 mm ×1 μm ). Moreover, a tiny shaker excites the cantilever at the fixed end, and a charge amplifier detects the charge accumulated in the PZT film. In the meantime, a laser vibrometer measures the deflection of the cantilever at three points along the PZT film, from which the strain is calculated using Euler–Bernoulli beam theory. Comparison of the strain and the charge amplifier voltage determines the calibration constant of the PZT thin-film sensor. The last goal is to demonstrate the use of the PZT thin film as a powerful actuator through active vibration control. In experiments, a tiny bulk PZT patch is first glued to the silicon cantilever. A function generator drives the bulk PZT simulating a source of disturbance exciting the silicon cantilever. In the meantime, a laser Doppler vibrometer (LDV) measures velocity of the cantilever tip. With a phase shifter as the controller, the LDV measurement is fed back to the PZT thin-film actuator to actively control the cantilever vibration. To evaluate the effectiveness of the active vibration control, a spectrum analyzer measures the frequency response functions (FRF) from the bulk PZT voltage to the LDV response. Experimental results show that the simple active vibration control scheme can reduce resonance amplitude of the first bending mode by 66%.

Piezoelectric transducers are known to exhibit less hysterisis when driven with current or charge rather than voltage. Despite this advantage, such methods have found little practical application due to the poor low frequency response of present current and charge driver designs. This paper introduces a new circuit topology free from low-frequency drift and DC load offsets. The hybrid load feedback charge amplifer contains a secondary low-frequency voltage feedback loop to stabilize the low-frequency and DC operation of the amplifier.

A CMOS operational amplifier with input/output rail-to-rail range is presented. The circuit operates with a 1-V single supply. It uses dynamically biased input level shifters, controlled by a novel tuning scheme, to extend the input common-mode voltage range from one rail to the other. The tuning circuit takes the total biasing current of the amplifier input stage and, hence, its small-signal response into account. As a result, the total input transconductance variations are lower than ±10% over the entire voltage range. Experimental results on a test-chip fabricated in standard 0.8-µm CMOS technology are given.

This article describes two generations of a novel integrated circuit multi-anode electron detector chip (LEDA512). This chip is designed for usage as an analog ion detector in magnetic mass spectrometers, in combination with a stack of two micro channel plates. The first generation chip is applied in a positive ion mass spectrometer on-board the ESA ROSETTA cometary mission. The detector chip comprises two identical and redundant parts, each consisting in a row of 512 rectangular anodes for electron collection, and in an anode multiplexer followed by a charge amplifier. A second-generation of the chip is scheduled. It will implement additional features, such as: radiation hard MOS transistors and shift registers and improved output drive capabilities.

The design and results of a radiation hard switched gain charge amplifier optimised for a large dynamic range and large input capacitance are described. The peaking time is 25 ns, dynamic ranges are 0.1–50 minimum ionising particles (MIPs) (high gain) and 1–400 MIPs (low gain), signal to noise (S/N)>10 for Cin