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Monitoring human health in real-time using wearable and implantable electronics (WIE) has become one of the most promising and rapidly growing technologies in the healthcare industry. In general, these electronics are powered by batteries that require periodic replacement and maintenance over their lifetime. To prolong the operation of these electronics, they should have zero post-installation maintenance. On this front, various energy harvesting technologies to generate electrical energy from ambient energy sources have been researched. Many energy harvesters currently available are limited by their power output and energy densities. With the miniaturization of wearable and implantable electronics, the size of the harvesters must be miniaturized accordingly in order to increase the energy density of the harvesters. Additionally, many of the energy harvesters also suffer from limited operational parameters such as resonance frequency and variable input signals. In this work, low frequency motion energy harvesting based on reverse electrowetting-ondielectric (REWOD) is examined using perforated high surface area electrodes with 38 µm pore diameters. Total available surface area per planar area was 8.36 cm2 showing a significant surface area enhancement from planar to porous electrodes and proportional increase in AC voltage density from our previous work. In REWOD energy harvesting, high surface area electrodes significantly increase the capacitance and hence the power density. An AC peak-to-peak voltage generation from the electrode in the range from 1.57-3.32 V for the given frequency range of 1-5 Hz with 0.5 Hz step is demonstrated. In addition, the unconditioned power generated from the harvester is converted to a DC power using a commercial off-theshelf Schottky diode-based voltage multiplier and low dropout regulator (LDO) such that the sensors that use this technology could be fully self-powered. The produced charge is then converted to a proportional voltage by using a commercial charge amplifier to record the features of the motion activities. A transceiver radio is also used to transmit the digitized data from the amplifier and the built-in analog-to-digital converter (ADC) in the micro-controller. This paper proposes the energy harvester acting as a self-powered motion sensor for different physical activities for wearable and wireless healthcare devices.

Bistable laminated composites are attractive for morphing structures because they can hold deformed stable shapes without any external energy and require actuation only to switch between shapes. They offer opportunities for shape morphing, energy harvesting, and flow control devices. Piezoelectric macrofiber composites (MFC) embedded in bistable laminates have been demonstrated for actuation and energy harvesting. However, their relatively high stiffness, relatively complex architecture, and arbitrary fiber orientation limit their ability to sense shape change in bistable laminates. There has been little work on the integration of sensing methods to monitor an adaptive structure’s shape; shape sensing has been investigated mainly for the detection of snap-through events. In this paper, we present self-sensing curved bistable laminates layered with piezoelectric PVDF films that can sense smooth changes as well as abrupt snap-through transitions. Measurement of smooth changes in the laminate’s curvature is enabled by an automated drift compensation charge amplifier with an extremely low cutoff frequency of 0.01 mHz. The sensing function is demonstrated on bistable laminates created using mechanical prestress. Two sensor layers are configured in the composite such that one measures change in curvature and the other measures snap-through response. The shapes measured by the sensor in terms of voltage correlate well with the shapes measured with a 3D motion capture system. An analytical model is developed to relate curvature change to voltage output and is found to be in good agreement with the measured curvature-voltage sensitivities. The weakly coupled shapes of the laminate and the low cross sensitivity of PVDF enable real-time measurement of the principal curvatures.

MEMS accelerometers are widely employed in the Internet of Things (IoT) era. Among them, capacitive types are commonly used due to their low cost and compatibility with the commercial CMOS fabrication lines. However, piezoelectric MEMS accelerometers have great research popularity attributed to their wide working range, self-generating property and removal of the need for vacuum sealing. This study designs, fabricates and analyzes a piezoelectriccantilever- beam-based accelerometer in meso scale, which is constructed by a tungsten proof mass and a composite beam comprising of PZT and stainless steel layers. Four structures with different geometries/dimensions are designed for comparison, including rectangular and trapezoid beam shapes. All the devices are fabricated by MEMS processes where aerosol deposition is utilized to make high-quality PZT sensing layer. And the implementation of stainless steel substrate makes the fabrication flow simple and cost-effective. Experiments show that the natural frequencies of the four structures range from 572.25 Hz to 769.01 Hz, corresponding to respective working frequency range from 110 Hz to 150 Hz. The low frequency limit of 10 Hz is determined by a tailor-designed charge amplifier, which is used to amplify the output charge signal of the developed sensor. At the working frequency of 95 Hz, charge sensitivities of 23.9 pC/g to 41.4 pC/g are measured for the four structures. Comparison with other studies, the designed devices have high sensitivities.

Mammography systems demand high quality imaging at reduced acquisition times. The Varex 3024MX imager was designed specifically with the demands of mammographic imaging in mind: high spatial resolution, excellent low contrast resolution as well as excellent low dose performance, and acquisition speeds capable of tomography. This paper will describe the details of the next generation a-Si mammography sensor array and contrast the predicate product, PS3024M. The Varex 3024MX imager delivers a 3584x2816 matrix with a pixel pitch of 83um resulting in an active area of 297.5mm x 233.7mm., optimized for mammography applications. A 250um thick deposited columnar CsI(Tl) layer is used as the scintillator. The development of a new pixel architecture and charge amplifier ASIC allows for faster readout of the sensor array at 16 bit pixel depth. The faster readout of the Varex 3024MX enables readout speeds up to 10fps. In addition to the faster frame rates, the combination of the new pixel architecture and ASIC, result in a very low electronic noise floor and improved ghosting behavior. The results, as outlined below, will show that the 3024MX design targeted improvements to detective quantum efficiency (DQE), maximum linear dose (MLD), quantum-limited dose (QLD), ghosting, and image readout time.

There is a need for high-performance force sensors capable of operating at frequencies near DC while producing a minimal mass penalty. Example application areas include steering wheel sensors, powertrain torque sensors, robotic arms, and minimally invasive surgery. The beta crystallographic phase polyvinylidene fluoride (PVDF) films are suitable for this purpose owing to their large piezoelectric constant. Unlike conventional capacitive sensors, beta crystallographic phase PVDF films exhibit a broad linear range and can potentially be designed to operate without complex electronics or signal processing. A fundamental challenge that prevents the implementation of PVDF in certain high-performance applications is their inability to measure static signals, which results from their first-order electrical impedance. Charge readout algorithms have been implemented which address this issue only partially, as they often require integration of the output signal to obtain the applied force profile, resulting in signal drift and signal processing complexities. In this paper, we propose a straightforward real time drift compensation strategy that is applicable to high output impedance PVDF films. This strategy makes it possible to utilize long sample times with a minimal loss of accuracy; our measurements show that the static output remains within 5% of the original value during half-hour measurements. The sensitivity and full-scale range are shown to be determined by the feedback capacitance of the charge amplifier. A linear model of the PVDF sensor system is developed and validated against experimental measurements, along with benchmark tests against a commercial load cell.

Energy harvesting (EH) derives from the idea of converting the ambient energy into electric energy, which can solve the problem of DC supply for some electronic equipment. PZT is a typical piezoelectric material of inorganic, which has been developed as EH devices to transfer ambient vibration energy into electric energy. However, these PZT devices require relatively violent excitation, and easy to be fatigue fracture under the resonance condition. In this paper, PVDF, which is a kind of soft piezoelectric polymer, is adopted for developing transducer. The PVDF devices are flexible and have longer life time than PZT devices under the harmonic environment. The EH researches are mainly focused on the development of energy transfer efficiency either by the mechanical structure of transducer or the improvement of circuit. However, the practicality and stability of the EH devices are important in the practical engineering applications. In this paper, a charge amplifier is introduced in the circuit in order to guarantee the stability of the battery charging under small ambient vibration conditions. The model of the mechanical structure of PVDF and the electric performance of circuit are developed. The experimental results and simulation show that the stability of battery charging is improved and the working time of DC equipment is prolonged.

The overload vehicles are making much more damage to the road surface than the regular ones. Many roads and bridges are equipped with structural health monitoring system (SHM) to provide early-warning to these damage and evaluate the safety of road and bridge. However, because of the complex nature of SHM system, it’s expensive to manufacture, difficult to install and not well-suited for the regular bridges and roads. Based on this application background, this paper designs a compact structural health monitoring system based on DSP, which is highly integrated, low-power, easy to install and inexpensive to manufacture. The designed system is made up of sensor arrays, the charge amplifier module, the DSP processing unit, the alarm system for overload, and the estimate for damage of the road and bridge structure. The signals coming from sensor arrays go through the charge amplifier. DSP processing unit will receive the amplified signals, estimate whether it is an overload signal or not, and convert analog variables into digital ones so that they are compatible with the back-end digital circuit for further processing. The system will also restrict certain vehicles that are overweight, by taking image of the car brand, sending the alarm, and transferring the collected pressure data to remote data center for further monitoring analysis by rain-flow counting method.

The development of a high purity germanium (HPGe) double sided strip detector prototype for X-ray astronomy is presented. The proposed design will cover the energy domain between 1 and 200 keV, and consists of a 4x4x1cm bulk with contacts on each side orthogonally segmented into 100 strips of 350μm width, with 50μm gap between strips. Both spectrometry and imaging capabilities have been taken into account in the design of the detector: on one hand, the use of germanium guarantees high spectral resolution; on the other hand, finely segmented contacts provide high precision on the position determination in the plane of the detector. In addition, the depth of the interactions can be estimated by looking at the difference of pulse raise time between the anode and the cathode. Pulse shape analysis and advanced algorithms are used for this purpose, obtaining a three-dimension localization of the point of impact of the photons. Furthermore, multiple interactions occurring simultaneously can be located, which makes the detector a suitable instrument for polarization measurements. The detection system relies on the extensive use of digital signal processing, with an early sampling of the signal at the output of the charge amplifier. This paper presents the measurement chain, including the detector itself, the electronic readout system and the signal processing methods that have been developped. The main results of the laboratory tests carried out at this stage are presented, and finally the measured performances of the detector are discussed.

In this work, an application of electrostatically tunable optical infrared filters in a closed-loop control system is presented. The filters are based on a Fabry-Perot architecture, fabricated in a bulk micromachining process. Compared to surface micromachined devices, this design opens a path to higher optical performance due to the high planarity and low roughness of substrates but also introduces the drawback of acceleration sensitivity because of a moving mass. To overcome this problem, the filter is driven by a closed-loop control system, with feedback from a charge amplifier that measures the capacitance of the control electrodes. A PI-based controller that adapts to nonlinear stiffness and damping by real-time calculation of the deflection dependent controller parameters is developed. Basic system parameters are derived from optical calibration measurements and step-response results. At 5 Hz sinusoidal accelerations of 1 g, the filter wavelength accuracy can be improved from ±35 nm in open-loop case down to ±2 nm in closed-loop operation.

In this study, an analogue Q-control circuit is presented, based on a digital feedback loop. In this approach, a self-actuated and self-sensing piezoelectric microstructure is used in combination with a lock-in amplifier to extract the Q-control feedback signal amplitude which is proportional to the piezoelectric current. In the next step, the DC-value supported by the lock-in amplifier is multiplied with a sine signal on a custom-designed analogue circuit board containing an analogue amplifier IC. This generated analogue feedback signal allows to drive a complete analogue feedback loop enabling faster response of the Q-control and further faster measurements can be performed. Using this Q-factor enhancement technique, the Q-factor was increased from 397 to about 5357 in air without driving the used Q-control approach to its limits. These promising results will push further activities in measuring the viscosity of liquids in the future.

Piezoelectric crystals have shown promising results as acoustic emission sensors, but are often hindered by the loss of electric properties above temperatures in the 500-700°C range. Yttrium calcium oxyborate, (YCOB), however, is a promising high temperature piezoelectric material due to its high resistivity at high temperatures and its relatively stable electromechanical and piezoelectric properties across a broad temperature range. In this paper, a piezoelectric acoustic emission sensor was designed, fabricated, and tested for use in high temperature applications using a YCOB single crystal. An acoustic wave was generated by a Hsu-Nielsen source on a stainless steel bar, which then propagated through the substrate into a furnace where the YCOB acoustic emission sensor is located. Charge output of the YCOB sensor was collected using a lock-in charge amplifier. The sensitivity of the YCOB sensor was found to have small to no degradation with increasing temperature up to 1000 °C. This oxyborate crystal showed the ability to detect zero order symmetric and antisymmetric modes, as well as distinguishable first order antisymmetric modes at elevated temperatures up to 1000 °C.

This paper discusses a capacitor transimpedance amplifier (CTIA) designed for an infrared readout circuit. The CTIA has better gain control, high dynamic range, a stability bias point and low impedance. It applies a short-wave detector and small current source because input impedance is very small in an amplifier feedback mechanism. This research on a capacitor transimpedance amplifier (CTIA) is designed for an infrared readout circuit. It is designed, simulated and laid out using the TSMC 0.35um 2P4M CMOS 5V process. The clock rate operates at 3MHz. Layout area is 30umX30um and the array size is 20X16. The simulation current sets 0.01nA~1.3nA. The output swing is 2.8V and power consumption is 10.1 mW according to the measurement results.

This paper studies the development of a PWAS-based wireless AE sensor that consumes around 2 mW. Low power charge amplifiers were designed and implemented to match the high impedance of the PWAS transducer to the low impedance of the passive wireless transponder. Two different designs of the charge amplifier were evaluated using an ultrasound pitch-catch system and pencil lead break experiments. Wireless acquisition of the AE signal was demonstrated. The low-power consumptions of the amplifiers indicate that a battery-less wireless AE sensor can be achieved using energy harvesting devices.

The measurement of stress of concrete structures under impact loading and other strong dynamic loadings is crucial for the monitoring of health and damage detection. Due to its main advantages including availability, extremely high rigidity, high natural frequency, wide measuring range, high stability, high reproducibility, high linearity and wide operating temperature range, piezoelectric (Lead Zirconate Titanate, PZT) ceramic materials has been a widely used smart material for both sensing and actuation for monitoring and control in engineering structures. In this paper, a kind of stress sensor based on piezoelectric ceramics for impact stress measuring of concrete structures is developed. Because the PZT is fragile, in order to employ it for the health monitoring of concrete structures, special handling and treatment should be taken to protect the PZT and to make it survive and work properly in concrete. The commercially available PZT patch with lead wires is first applied with an insulation coating to prevent water and moisture damage, and then is packaged by jacketing it by two small precasted cylinder concrete blocks with enough strength to form a smart aggregate (SA). The employed PZT patch has a dimension of 10mm x 10mm x 0.3mm. In order to calibrate the PZT based stress sensor for impact stress measuring, a dropping hammer was designed and calibration test on the sensitivity of the proposed transducer was carried out with an industry charge amplifier. The voltage output of the stress sensor and the impact force under different free falling heights and impact mass were recorded with a high sampling rate data acquisition system. Based on the test measurements, the sensibility of the PZT based stress sensor was determined. Results show that the output of the PZT based stress sensor is proportional to the stress level and the repeatability of the measurement is very good. The self-made piezoelectric stress sensor can be easily embedded in concrete and provide reliable stress sensing under dynamic loadings.

This paper presents analysis of processing method of the signal from Gas Electron Multiplier (GEM) detector acquired in our Field-Programmable Gate Array (FPGA) based readout system. We have found that simple processing of GEM signal received from the charge amplifier, sampled at 100MHz with 10-bit resolution, after low-pass filtering with 15 MHz cut-off frequency, provides accuracy similar to obtained by processing of the raw GEM signal sampled at 2.5 GHz frequency with 8-bit resolution. Even when 3 bits are lost due to long term instability of the detector and analog part of the system - resulting in 7-bit effective resolution, the reasonable accuracy is still preserved. Additionally we have analyzed computational power required to perform the real-time analysis of the GEM signal, taking into consideration resources offered by the FPGA chip used in the prototype platform.

A new and novel detector structure is now being investigated to minimize the readout noise of large area TFT arrays. A conventional TFT panel consists of orthogonal arrays of gate lines and data lines. The parasitic capacitance from the crossover of these lines results in a sizable data line capacitance. During image readout, the thermal noise of the charge integrator is greatly magnified by the ratio of the data line capacitance to the feedback capacitance of the charge amplifier. The swinging of the gate voltage will also inject charges in and out of the imaging holding pixel capacitors and contribute to the switching noise in the readout image. By redesigning the layout of the TFT arrays and by coupling linear light source to the bottom side of the TFT array in the same direction as the gate lines, the crossover of gate lines and data lines can be avoided and the data line capacitance can be greatly reduced. Instead of addressing each row of transistors by the switching of the gate control voltage, linear light source with collimators are used to optically switch on and off the amorphous silicon transistors. The transistor switching noise from the swinging of the gate voltages is reduced. By minimizing the data line capacitance and avoiding the swinging of the gate control voltage, the basic TFT readout noise is minimized and lower dose x-rays images can be obtained. This design is applicable to both Direct Conversion and Indirect Conversion panels.

For the demands of high speed and efficiency of on-line measurement of roundness in machining industry, a kind of High-speed roundness measurement system based on the piezoelectric displacement transducer that used the Polyvinylidene fluoride film was developed. It can achieve the goal of high-speed roundness measurement by combining with charge amplifier and taking advantages of transducer such as the high frequency, sensitivity and signal-to-noise ratio. From the experiment study, known that the measuring frequency response of the PVDF transducer is over 1200Hz and the resonance peak is about 3000Hz. It has solved the problem of distortion measurement that caused by the inductive transducer in high-speed measurement. The results showed that this system roundness error measurement precision can reach less than 1μm. Repeated measurements show that the measurement results of the system has high reproducibility and reliability.

The large interest shown in the field of terahertz detectors research by the scientific community brought to the development of several kinds of devices based on different principles. Many, however, have some peculiar characteristics that prevent their use in low-cost or compact equipment, because of cryogenic cooling, or the use of exotic materials, etc. Recently, approaches using field-effect transistors exploiting the oscillation of electron density (plasma waves) or the phenomena known as "self-mixing" in RF modulators, allowed to foresee the possibility to employ standard CMOS technologies to build such sensors. In this work we analyze the behavior of this kind of detectors in order to understand how to design an optimized device and then how to exploit it by proper readout. Optimized electromagnetic coupling to the detector has been implemented using a dipole antenna. Electromagnetic simulations together with the developed model allowed calculating a projected noise figure of the detector of 38ρW / √Hz. Two dedicated readout circuits have been designed, one intended to read the detector as a current generator, while the other reads it as a voltage generator. The developed circuits have been designed and sent for fabrication in a standard 0.35μm CMOS technology.

For large civil engineering structures and base establishments, for example, bridges, super-high buildings, long-span space structures, offshore platforms and pipe systems of water & gas supply, their lives are up to a few decades or centuries. Damaged by environmental loads, fatigue effects, corrosion effects and material aging, these structures experience inevitably such side effects as damage accumulation, resistance reduction and even accidents. The traditional civil structure is a kind of passive one, whose performance and status are unpredictable to a great extent, but the informatics' introduction breaks a new path to obtain the status of the structure, thus it is an important research direction to evaluate and improve reliability of civil structures by the use of monitoring and health diagnosis technique, and this also assures the security of service for civil engineering structures. Smart material structure, originated from the aerospace sector, has been a research hotspot in civil engineering, medicine, shipping, and so on. For structural health monitoring of civil engineering, the research about high-performance sensing unit of smart material structure is very important, and this will possibly push further the development and application of monitoring and health diagnosis techniques. At present, piezoelectric materials are one of the most widely used sensing materials among the research of smart material structures. As one of the piezoelectric materials, PVDF(Polyvinylidene Fluoride)film is widely considered for the advantages of low cost, good mechanical ability, high sensibility, the ability of being easily placed and resistance of corrosion. However, only a few studies exit about building a mature monitoring system using PVDF. In this paper, for the sake of using PVDF for sensing unit for structural local monitoring of civil engineering, the strain sensing properties of PVDF are studied in detail. Firstly, the operating mechanism of PVDF is analyzed. Secondly, wireless collection system of PVDF is integrated with PVDF film, charge amplifier, wireless transceiver and the corresponding software. Then, with strain gauge as a reference, experiments have also been done to study the quasi-static and dynamic strain response of PVDF, such as sensitivity, linearity and frequency responding, etc. The experimental results show that PVDF is sensitive to the impact response of civil engineering structures, and can provide local monitoring in different frequency response cooperating with a strain gauge. The developed wireless collection system has the characteristics of no lines, saving cost and installation time, and thus further pushes the practical application of PVDF for civil engineering structures.

The Transverse Field Detector (TFD) is a recently proposed Silicon pixel device designed to perform color imaging without the use of color filters. The color detection principle is based on the dependence of the Silicon absorption coefficient from the wavelength and relies on the generation of a suitable transverse electric field configuration, within the semiconductor active layer, to drive photocarriers generated at different depths towards different collecting electrodes. Each electrode has in this way a different spectral response with respect to the incoming wavelength. Pixels with three or four different spectral responses can be implemented within ~ 6 μm of pixel dimension. Thanks to the compatibility with standard triple well CMOS processes, the TFD can be used in an Active Pixel Sensor exploiting a dedicated readout topology, based on a single transistor charge amplifier. The overall APS electronics includes five transistors (5T) and a feedback capacitance, with a resulting overall fill factor around 50%. In this work the three colors and four colors TFD pixel simulations and implementations in a 90 nm standard CMOS triple well technology are described. Details on the design of a TFD APS mini matrix are provided and preliminary experimental results on four colors pixels are presented.

Several researchers are actively studying Ionomeric polymer transducers (IPT) as a large strain low voltage Electro- Active Polymer (EAP) actuator. EAPs are devices that do not contain any moving parts leading to a potential large life time. Furthermore, they are light weight and flexible. IPT have the ability to generate bending strains on the order 5% when +2V potential is applied across its thickness. As sensors however, IPTs are proven to be superior compared to any other EAP material when a charge amplifier is used as a signal conditioner. Furthermore, researchers has developed miniature sensors from IPTs that could be flush mounted to a surface and measure shear stresses due to fluid flow at even low Reynolds numbers. Sensor resolution is on the order of 10 mPa enables it to be useful as a wall shear stress sensor for several aero/hydrodynamic and biomedical applications. In this paper a new signal conditioning circuit is designed with superior sensing capabilities compared to the old circuit. In the new circuit the IPT is biased with a small voltage on the order of 5mV to 25 mV. Initial experimental results demonstrated 30% enhancement in signal to noise ratio compared to the old circuit. Furthermore, this circuit enables the use of IPT polymers with larger capacitance compared to the previous circuits. Akle et al. demonstrated that the capacitance of an ionic polymer transducer is proportional to transducer performance. Ionic polymers are generally made of an ion exchange membrane, typically Nafion, coated with a flexible electrode. In this study the Direct Assembly Process (DAP) is used for the fabrication of IPT. The DAP consists of mixing a metal particulate with an ionomer solution and spraying it directly on a diluent saturated ion conducting membrane. The thickness of the electrode is controlled by altering the amount of the ionomer/metal mix sprayed on the membrane. Thicker electrodes provide IPT with a larger capacitance, and hence larger sensitivity is obtained using the new circuit. It was impossible to use the previous signal conditioning circuit for high capacitance sensors. Finally an attempt to model these sensors along with the circuit is provided. By understanding the interaction between the IPT and the signal conditioning circuit we can create devices with even higher sensitivity. The presented circuit will help in modeling and predicting the response of the sensor.

An energy-discriminating K-edge x-ray Computed Tomography (CT) system is useful for increasing contrast resolution of a target region and for diagnosing cancers utilizing a drug delivery system. The CT system is of the first generation type and consists of an x-ray generator, a turn table, a translation stage, a two-stage controller, a cadmium telluride (CdTe) detector, a charge amplifier, a shaping amplifier, a multi-channel analyzer (MCA), a counter board (CB), and a personal computer (PC). The K-edge CT is accomplished by repeating translation and rotation of an object. Penetrating x-ray spectra from the object are measured by a spectrometer utilizing the CdTe detector, amplifiers, and MCA. Both the photon energy and the energy width are selected by the MCA for discriminating photon energy. Enhanced iodine K-edge x-ray CT was performed by selecting photons with energies just beyond iodine K-edge energy of 33.2 keV.

The most widely used architecture in large-area amorphous silicon (a-Si) flat panel imagers is a passive pixel sensor (PPS), which consists of a detector element and a readout switch. While the PPS has the advantage of being compact and amenable toward high-resolution imaging, reading small PPS output signals requires external column charge amplifiers that produce additional noise and reduce the minimum readable sensor input signal. In contrast, on-pixel amplifiers in a-Si technology reduce readout noise by decoupling off-pixel noise sources, such as external charge amplifier and data line noise, from the sensor input. The off-pixel noise is reduced by the charge gain of the pixel amplifier, allowing for low-noise performance. Theoretical calculations and simulations of gain, linearity, metastability, pixel area requirements and noise indicate the applicability of the amplified a-Si pixel architectures for low-exposure, real-time fluoroscopy. In addition, the detailed noise results allow for the computation of noise performance as a function of transistor dimensions for both amorphous silicon and polysilicon technologies, allowing the designer to choose appropriate device dimensions when designing flat-panel imaging circuits.

Experimental techniques in physics, material science, biology and medicine want to gain profit from the advantages of the VLSI technology by using a new generation of electronic measurement systems based on parallel signal processing from the multielement sensors. In most cases key problems for building such system are multichannel mixed-mode Application Specific Integrated Circuits, which are capable to process small amplitude signals from multielement sensor. In this class of integrated circuits several important problems like power limitation, low level of noise, good matching performance and crosstalk effects must be solved simultaneously. This presentation shows two ASICs which, given the original solutions implemented and their universal properties, can be used in different applications and are significant milestones in experimental techniques. The first presented ASIC is the 64-channel charge amplifier with binary readout architecture for a low energy X-ray imaging techniques. This integrated circuit connected to silicon strip detector can be used in powder diffractometry and then it reduces the measurement time by two order of magnitude. The second presented ASIC is multichannel low noise readout for extracellular neural recording, which is able to cope with extracellular neuronal recording for the systems comprising several hundreds of electrodes. Important steps forward in this design are a novel solution for band-pass filters for low frequency range, which follow requirements for good matching, low power and small silicon area. This ASIC can be used to monitor the neural activity of such complicated system like retina or brain.

This paper presents the whole process of building up a high precision, high dynamical MEMS acceleration sensor. The first samples have achieved a resolution of better than 500 ug and a bandwidth of more than 200 Hz. The sensor fabrication technology is shortly covered in the paper. A theoretical model is built from the physical principles of the complete sensor system, consisting of the MEMS sensor, the charge amplifier and the PWM driver for the sensor element. The mathematical modeling also covers problems during startup. A reduced order model of the entire system is used to design a robust control with the Mixed-Sensitivity H-infinity Approach. Since the system has an unstable pole, imposed by the electrostatic field and time delay, caused by A/D-D/A conversation delay and DSP computing time, limitations for the control design are given. The theoretical model might be inaccurate or lacks of completeness, because the parameters for the theoretical model building vary from sample to sample or might be not known. A new identification scheme for open or closed-loop operation is deployed to obtain directly from the samples the parameters of the mechanical system and the voltage dependent gains. The focus of this paper is the complete system development and identification process including practical tests in a DSP TI-TMS320C3000 environment.

Since a switched-capacitor sample-and-hold amplifier (SHA) has a feedback loop outside its op-amp, an op-amp with positive feedback technique (PFT) can be adopted to enhance the DC-gain of the op-amp. This paper proposes a positive feedback amplifier with dramatically increased DC-gain of 127-dB and reports that a SHA adopting proposed amplifier is stable by feedback operation. Measurement results demonstrated stable operation with spurious free dynamic range (SFDR) of 70-dB.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The work presented relates to the design and construction of an inexpensive distributive load sensor. It is to be used for impact tests on samples which are in the form of flexible or deformable beams of a considerable length. The sensor compromises of forty fingers made of steel, arranged next to each other and covering a total length of about a meter. Both ends of each finger are clamped. PZT ceramic patches, which are bonded to the bottom surfaces of each finger, are used to convert the impact response into an electrical signal. An amplifier and filter were designed for each finger. The frequency range over which each finger operates is extended by the use of a Butterworth filter. An amplifier box was built containing the charge amplifier circuitry and filter of each of the forty fingers comprising the distributive sensor. Tests are performed on the distributive sensor in order to show that this simple and inexpensive distributive sensor is effective. The results are presented and discussed.

Amorphous selenium direct-conversion x-ray detectors have been used successfully for full field digital mammography (FFDM) and digital radiography (DR). Such detectors characteristically exhibit high spatial resolution and conversion efficiency that is a function of the applied electric field. At an electric field of 10 volts per micron, about 50 electron volts of photon energy are required to generate an electron-hole pair in a typical amorphous selenium x-ray conversion layer. At FFDM and DR imaging x-ray energies each absorbed photon can generate only about 250 to 1000 electron-hole pairs. Each absorbed x-ray photon is only contributing 4 x 10-17 to 1.6 x 10-16 coulombs of imaging charge. On the noise side, detectors operating at room temperature have a basic thermal (kTC) noise of 300 to 600 electrons per pixel from the image charge storage capacitor. Electronic noise from the front-end charge amplifier is also amplified by one plus the ratio of the TFT data line capacitance and the feedback capacitance of the charge amplifier. Medical imaging applications must therefore employ low noise thin film transistor (TFT) arrays, low data line capacitance and low noise charge integration amplifiers to achieve high signal-to-noise ratio (SNR) and detective quantum efficiency (DQE). To achieve quantum-noise limited imaging results with the lowest practical x-ray exposure dose, it is desirable to include an additional low-noise gain stage in the x-ray conversion layer. This is particularly important for the application of dynamic imaging or for tomosynthesis where x-ray dose per frame is very limited. A new structure for an amorphous selenium detector that employs an internal biased gain grid to cause avalanche-gain within the x-ray conversion layer is being proposed. A signal charge amplification of at least 10X can be achieved without introducing excessive noise. Quantum-limited image detection should then be attainable for even very low exposures.

We developed and evaluated a prototype flat-panel detector based Volume CT (VCT) scanner. We focused on improving the image quality using different detector settings and reducing x-ray scatter intensities. For the presented results we used a Varian 4030CB flat-panel detector mounted in a multislice CT-gantry (Siemens Medical Systems). The scatter intensities may severely impair image quality in flat-panel detector CT systems. To reduce the impact of scatter we tested bowtie shaped filters, anti-scatter grids and post-processing correction algorithms. We evaluated the improvement of image quality by each method and also by a combination of the several methods. To achieve an extended dynamic range in the projection data, we implemented a novel dynamic gain-switching mode. The read out charge amplifier feedback capacitance is changing dynamically in this mode, depending on the signal level. For this scan mode dedicated corrections in the offset and gain calibration are required. We compared image quality in terms of low contrast for both, the dynamic mode and the standard fixed gain mode. VCT scanners require different types of dose parameters. We measured the dose in a 16 cm CTDI phantom and free air in the scanners iso-center and defined a new metric for a VCT dose index (VCTDI). The dose for a high quality VCT scan of this prototype scanner varied between 15 and 40 mGy.

The effect of finite open-loop gain in charge amplifiers in digital radiography (DR) is analyzed. Practical charge amplifiers are usually integrated into silicon chips and commonly cater to 128 columns. High gains in charge amplifiers have a cost that is associated with greater chip count, greater power dissipation, and sometimes, reduced bandwidth. Even an open-loop gain of 1000 in a charge amplifier can lead to visible artifacts in a DR system, for temperature drifts of a fraction of a degree between calibration of a panel and subsequent usage, while acquiring a radiographic image. Furthermore, small gains in a charge amplifier can rob charge from the pixel capacitor and create residual charge, predominantly in the column capacitances. This can reduce the effective signal-to-noise ratios (SNRs). Analytical models are developed to illustrate the effects of the finite gain in charge amplifiers. Methods are suggested to decrease the deleterious effects of finite gains in charge amplifiers.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This work presents a novel design for a micromachined, capacitively sensed hydrophone. The design consists of a fluid-filled chamber constrained by two sets of membranes. The "input" membranes are arrayed around the outside of the circular chamber. Incoming sound generates a trapped cylindrical wave, creating mechanically amplified motion of the 1 mm diameter central "sensing" membrane. The membrane material is a LPCVD nitride/oxide/nitride triple-stack with respective film thickness 0.1/0.65/0.1 micron. The chamber is filled with 200 cSt viscosity silicone oil. Fluid-filling eases design constraints associated with submerging the sensor, especially with respect to exterior mass loading. Both silicon-glass anodic bonding and tin-gold solder bonding are used to form the structure, including the 5 micron sensing gap. The fluid-structure system is computationally modeled using both approximate analytic and numerical techniques. Model results indicate a 28 dB displacement gain between the motion of the "input" membranes and the "sensing" membranes. An off-chip charge amplifier, with a 10 pF integrating capacitor, is used to convert membrane motion into an electrical signal. Mean measured system sensitivity is 0.8 mV/Pa (-180 dB re 1 V/microPa) from 300 Hz-15 kHz with a 1.5 volt applied bias and a 26 dB preamplifier gain. The predicted low frequency sensitivity is 0.3 mV/Pa. The measured sensitivity exhibits considerable scatter below 7 kHz, with a standard deviation of 80%. Laser vibrometry measurements indicate that this scatter may be caused by compliance of the chip mounting scheme. Above 10 kHz, the quiescent noise is -100 dB re 1 V/rtHz. Noise characteristics exhibit a 1/f character below 10 kHz, rising to a maximum of -50 dB re 1 V/rtHz at 100 Hz.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Organic strain gauge and other sensors require high-gain, precision dc amplification to process their low-level output signals. Ideally, amplifiers would be fabricated using organic thin-film field-effect transistors (OTFT's) adjacent to the sensors. However, OTFT amplifiers exhibit low gain and high input-referred dc offsets that must be effectively managed. This paper presents a four-stage, cascaded differential OTFT amplifier utilizing switched capacitor auto-zeroing. Each stage provides a nominal voltage gain of four through a differential pair driving low-impedance active loads, which provide common-mode output voltage control. p-type pentacence OTFT's are used for the amplifier devices and auto-zero switches. Simulations indicate the amplifier provides a nominal voltage gain of 280 V/V and effectively amplifies a 1-mV dc signal in the presence of 500-mV amplifier input-referred dc offset voltages. Future work could include the addition of digital gain calibration and offset correction of residual offsets associated with charge injection imbalance in the differential circuits.

This paper describes a new flat panel imager designed for use in cardiovascular and mobile C-arm imaging systems. The a-Si sensor array has a 1024 x 1024 matrix with a pixel pitch of 194 μm, resulting in an active area of 198.7 mm x 198.7 mm. The imager allows frame rates of up to 30 fps in full resolution fluoroscopy mode and up to 60 fps in a 2 x 2 binned low dose fluoroscopy mode. Typically, a 600 μm thick deposited columnar CsI(Tl) layer is used as the scintillator. Improvements in the pixel architecture, charge amplifier ASICs, and system level electronics resulted in a very low electronic noise floor, such that both the fluoroscopy and low dose fluoroscopy modes of the panel are x-ray quantum limited below 1 μR/frame. Low power consumption electronics combined with a mechanical design optimized for heat transfer and dissipation makes air-cooling sufficient for most environments. The small size of 24.1 x 24.1 x 6 cm and the weight of only 4.1 kg meet the requirements of C-Arm systems. Special consideration was given to the border around the active area, which has been reduced to 2 cm. Reported performance parameters include linearity, lag, contrast ratio, MTF, and DQE. For the full resolution mode, the MTF is greater than 0.53 and 0.21 at 1 and 2 lp/mm, respectively. DQE measured at 22 nGy/frame was greater than 0.68, 0.50, and 0.23 at 0, 1, and 2 lp/mm, respectively.

The dynamic range of many flat panel imaging systems are fundamentally limited by the dynamic range of the charge amplifier and readout signal processing. We developed two new flat panel readout methods that achieve extended dynamic range by changing the read out charge amplifier feedback capacitance dynamically and on a real-time basis. In one method, the feedback capacitor is selected automatically by a level sensing circuit, pixel-by-pixel, based on its exposure level. Alternatively, capacitor selection is driven externally, such that each pixel is read out two (or more) times, each time with increased feedback capacitance. Both methods allow the acquisition of X-ray image data with a dynamic range approaching the fundamental limits of flat panel pixels. Data with an equivalent bit depth of better than 16 bits are made available for further image processing. Successful implementation of these methods requires careful matching of selectable capacitor values and switching thresholds, with the imager noise and sensitivity characteristics, to insure X-ray quantum limited operation over the whole extended dynamic range. Successful implementation also depends on the use of new calibration methods and image reconstruction algorithms, to insure artifact free rebuilding of linear image data by the downstream image processing systems. The multiple gain ranging flat panel readout method extends the utility of flat panel imagers and paves the way to new flat panel applications, such as cone beam CT. We believe that this method will provide a valuable extension to the clinical application of flat panel imagers.

We present an ASIC for synchronized excitation of electrostatically driven resonant micro scanning mirrors which have been developed and fabricated at the Fraunhofer IMS for several years. The mirror oscillation is excited with a rectangular driving signal and operated close to the characteristic frequency or higher. Deflection amplitude is maximum if the driving voltage is switched off precisely at the cross-over of the oscillation. We have developed and fabricated a mixed signal ASIC that starts the oscillation and runs the mirror with high efficiency by detecting the oscillation cross-over. For that, the ASIC senses the varying capacitance of the actuator’s comb-drive electrodes and converts it with a clocked charge amplifier into a voltage. The amplified capacitance signal is processed by a synchronization module which detects the minimum of the capacitance signal corresponding to the cross-over of the oscillation. An integrated charge pump provides the driving voltage. The ASIC has been fabricated at the facilities of the IMS with a 1.2 μm CMOS process. Tests with a demonstrator PCB have shown that the synchronization works highly efficient with a value of appr. 96 %. A mechanical deflection angle of ± 13° was achieved for a micro-mirror with a characteristic frequency of 250 Hz at a driving voltage of 13.5 V, only.

The application of PZN-PT single crystal piezoceramic in low-cost, high-resolution strain sensors was examined using an ACX QuickPack PZT strain sensor as a basis for the new design, with active structural control of precision machinery as the target application. A study was performed to determine the influence of mechanical feedthrough on the sensor signal. Mechanical feedthrough appears when an actuator is close to the sensor and near-field effects dominate the actuator-to-sensor transfer function. Both voltage follower and charge amplifier signal conditioning electronics were tested, and the benefits of each on the nonlinear characteristics of PZT and PZN-PT were analyzed. Finally, the coherence between the sensor characteristics was analyzed. The results show that the QuickPack strain sensor compares favorably with some higher cost off-the-shelf products in terms of noise and resolution, at a significantly lower cost. The single crystal sensors show significantly higher sensitivity than their conventional multi-crystalline counterparts, though less than expected due to the softer base material.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The aim of the present paper is to illustrate the configuration and the performances of a charge feedback amplifier to drive a piezoelectric transducer in self-sensing operation, i.e. to use the same transducer as sensor and actuator at the same time. A suitable balancing procedure of the self-sensing circuit allows to obtain an output signal proportional to the displacement of the mechanical structure. Experimental tests show that the proposed charge feedback amplifier simplifies the balancing procedures needed to obtain a useful output signal from the self-sensing readout circuit, this is attributed to the increased stability of the electric parameters of the piezoelectric that can be achieved with charge control.

Previously we have described several types of charge division electronic image readouts for microchannel plate based imaging detectors developed at MSSL, primarily for space astronomy applications. These have included the wedge and strip anode1 (WSA), the Vernier anode2 - a high resolution readout, capable of exploiting the limiting spatial resolution offered by the microchannel plate, and FIRE3 - an imaging device operating at event rates in excess of 10 MHz. MSSL and Photek have now joined in collaboration to develop an intensifier based imaging system designed to employ this range of readout systems for general laboratory use. The image intensifier uses the image charge technique4,5 whereby the event charge is used to induce electrical signals on the capacitively coupled readout pattern, obviating the requirement for the readout to be inside the vacuum enclosure. The image readout is manufactured as a separate component, and can be interchanged to suit the specific application requirements. The intensifier tube design can be generic enabling it to be used with a variety if image readouts designs. We describe the image intensifier and electronic design, including the common charge amplifier, event timing and computer interface. We discuss the anticipated performance of the various readout systems - Wedge and Strip, Vernier and FIRE in terms of spatial resolution, maximum count rate, and timing resolution.

Following our previous report concerning the development of a 127 micrometer resolution, 7.4 million pixel, 30 X 40 cm2 active area, flat panel amorphous Silicon (a-Si) x-ray image sensor, this paper describes enhancements in image sensor performance in the areas of image lag, linearity, sensitivity, and electronic noise. New process improvements in fabricating a-Si thin film transistor (TFT)/photodiode arrays have reduced first-frame image lag to less than 2%, and uniformity in photoresponse to less than 5% over the entire 30 X 40 cm2 active area. Detailed analysis of image lag vs. time and x-ray dose will be discussed. An improved charge amplifier has been introduced to suppress image cross-talk artifacts caused by charge amplifier saturation, and system linearity has been optimized to eliminate banding effects among charge amplifiers. Preliminary sensitivity improvements through the deposition of CsI(Tl) directly on the arrays are reported, as well as overall imaging characteristics of this improved image sensor.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We present a VLSI digital-analog readout electronic chain for silicon microstrip detectors. The characteristics of this circuit have been optimized for the high resolution tracker of the CERN CMS experiment. This chip consists of 128 channels at 50 micrometers pitch. Each channel is composed of a charge amplifier, a CR-RC shaper, an analog memory, an analog processor, an output FIFO which is read out serially by a multiplexer. This chip has been processed in the radiation hard technology DMILL. This paper describes briefly the architecture of the circuit and presents test results of the 128 channel full chain chip before and after irradiation up to 10 Mrad.

A surface micromachined accelerometer which senses an inertial motion with an area variation and a force balancing electrodes is developed. The grid-type planar mass of a 7 micrometers thick polysilicon is supported by four thin beams and suspended above a silicon substrate with a 1.5 micrometers air gap. The motion sensing electrodes are formed on the substrate. The sensor is designed as an interdigital rib structure that has a differential capacitor arrangement. The moveable electrodes are mounted on the mass and the pairs of the stationary electrodes are patterned on the substrate. In the accelerometer that has comb-type movable electrodes, the mechanical stress and the electrical pulling effects between a moveable electrodes and the fixed electrodes occur. However this grid-type structure can have a large area variation in a small area relatively without stress and pulling, high sensitivity can be achieved. In order to improve the dynamic rang and a linearity, a pair of comb shape force-balancing electrodes are implemented on both sides of the mass. The force-balancing electrodes are made of the same layer as the mass and anchored on a silicon substrate. When acceleration is applied in the lateral direction, the difference of capacitance results from the area variation between the two capacitors and is measured using a charge amplifier. As AC coupled complimentary pick- off signals are applied in paris of stationary electrodes, the undesirable effects due to temperature and electrical noise are reduced effectively. The accelerometer has a sensitivity of 28mV/g and a bandwidth of DC-120Hz. A resolution of 3mg and a non-linearity of 1.3 percent is achieved for a measurement range of +/- 9 g.

The composite thin-film IR image detector consists of pyroelectric, LCD and electronic information processing technique. It can reproduce thermal image directly under the condition of uncooled, room temperature. The pyroelectric film signal charge amplifier and LCDs are its mainly components. It is respectively composed of PVDF (or PVDF- TGS, PVDF-PZT) film, TFT and LC film. The device properties parameter are relatively high level, D* approximately 108cmHz1/2w-1, NEP approximately 10-9 W and NETD approximately 10-1 K. The four units is a IR signal detector and to make a foundation for 32 X 32 units and above of multiunits plane array. It is a novel, convenient thermal detecting device and possesses a quite prospects of development and application.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The laser confocal microscope (LCM) is now an established research tool in biology and materials science. In biological applications, it is usually employed to detect the location of fluorescent market molecules and, under these conditions, signal levels from bright areas are often < 20 photons/pixel (from the specimen, assuming a standard 512 X 768, 1 sec. scan). Although this data rate limits the speed at which information can be derived from the specimen, saturation of the fluorophor, photobleaching of the dye, and phototoxicity prevent it being increased. Currently, most LCMs use photomultiplier tubes (PMT, QE equals 1 - 30% 400 - 900 nm). By contrast, rear-illuminated, scientific charge-coupled devices (CCD) now routinely readout the signal from square sensors approximately 30 micrometers on a side with a QE of 80 - 90%, a noise of only +/- 3 e-/pix and with no multiplicative noise. For this reason, in 1989, one of us (JJ) developed a rear-illuminated, single-channel Si sensor, called the Turbodiode, employing some of the sophisticated readout techniques used to measure charge in a scientific CCD. We are now extending this work to a device in which a single 36 X 36 micrometers sensor is read out through a low-noise FET charge amplifier with a reset circuit and then passed to a correlated, double-sampling digitizer. To maintain the desired +/- 3 e noise level at the relatively high data rate of 1 MHz, our new device utilizes 64 separate readout amplifier/digitizer systems, operating in sequence. The resulting detector is more compact, efficient and reliable than the PMT it replaces but as its sensitive area is smaller than that of a PMT, it will require auxiliary optics when used with any LCM having a large (mm) pinhole. As the signal light is parallel, a simple lens mounted axially and with the CCDiode at its focus would suffice. Future versions may use 3 X 3 or 5 X 5 arrays of sensors to `track' the confocal spot as it is deflected by inhomogeneities of the specimen, change its effective size or shape or detect system misalignment.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

1K by 1K UV Photon Counting Array (PCA) imaging detectors have been built for the Space Telescope Imaging Spectrometer (STIS) program by Ball Aerospace in Boulder, Colorado. The STIS detectors are the largest of this type everproduced. These detectors have unique electronic and electro-mechanical requirements. This paper discusses the STIS PCA detector (MAMA detector) charge amplifier and discriminator electronic and packaging requirements. Critical system parameters, including speed, noise, power consumption, and size are described. Cost drivers including fabrication methods, test methods, and production techniques are discussed. Additional cost reduction techniques suitable for ground-based systems will be suggested. System requirements and circuit performance are comparedto demonstrate that performance meets or exceeds all system requirements. 1. INTRODUCTION The STIS MAMA Detector electronics uses a proprietary analog application specific integrated circuit (ASIC) pair de-signed at Ball Aerospace in Boulder, Colorado. There are two types ofASICs: a charge amp and a dual voltage discriminator.The die were fabricated by Tektronix using their QC 6 process and packaged by Kyocera USA in ceramic, hermetic, J leadedpackages.1Surface mount technology was used to reduce size, fabrication cost, and facilitate repair. The use of surface mount parts,rather than through-hole mounted parts, greatly reduces the probability of damaging the multilayer boards during rework andincreases reliability.The only through-hole components used were select resistors. These parts were used in small numbers to eliminate theneed to stock a large selection of surface mount resistors since the leaded resistors were already in stock at Ball.

Prototype ICs for the Solar Heliospheric Observatory's Multi-Anode Microchannel Array (MAMA) have been developed; these ICs' charge-amplifier and comparator components were then tested with a view to pulse response and noise performance. All model performance predictions have been exceeded. Electrostatic discharge protection has been included on all IC connections; device operation over temperature has been consistent with model predictions.

This paper describes an implementation of a recently developed charge amplifier, called Integration Amplifier, in the UKIRT 7 channel spectrometer (CGS2), resulting in the conversion of the CGS2 from the traditional transimpedance amplifier to a commercial charge integration scheme. Also described is a new data acquisition system; the news system allowed the implementation of a noise reduction algorithm which is a mojor factor in the improved sensitivity of CGS2. The noise reduction algorithm is presented together with a system diagram of CGS2.

The different image sensors using a photoconductor as X ray to electric charges converter and optical techniques for image adressing or read out are reviewed, with a special attention to x ray photoconductor. 1. BASIC PRINCIPLES. The photoconductor may be used with one or two transparent Blocking Electrodes (BE) and subjected during recording to a constant voltage ; therefore, the image is recorded as spatial space charge distribution at the interface(s) photoconductor / dielectric. An other possibility consists in recording the space charge in the bulk of the photoconductor, in which photocarriers traps are provided in the bandgap. In that case, transparent Ohmic Electrodes (OE) are deposited on the photoconductor ; the electric field may be parallel to the light beam (longitudinal configuration OEL) or perpendicular (Transverse configuration GET). In the dark, under short circuit conditions, the storage time of the recorded latent image is in first approximation equal to the dielectric relaxation time of the structure. Optical read out of the latent image can be performed following two techniques. First, the electrodes can be connected to a charge amplifier, which output modulates the Wehnelt of a CRT ; a light beam is deflected 139

A monolithic Midwave InfraRed (MIR) sensitive array based on PbTe photoconductive sensors and a silicon CCD current integrator and multiplexer is manufactured and evaluated.. The dark current of the devices can be kept sufficiently low to allow for integration times of 4.4 msec. The responsivity and the detectivity D* of the device are quite high and can be compared to other types of IR sensors for the same wavelength range. The responsivity uniformity of the PbTeCCD is better than 10 %.