Readout Process Research Articles

Nondestructive Probing of a Photoswitchable Dithienylethene Coupled to Plasmonic Nanostructures

We demonstrate the read-out of the conformational state of photoswitchable molecules, without modifying that state by the read-out process itself. The ring-opening and ring-closing reactions change not only the absorption spectrum of a molecular layer but also its index of refraction. A thin layer of a dithienylethene derivative was combined with well-designed gold nanostructures. The particle plasmon resonance of these nanostructures is extremely sensitive to the photoinduced change in the environment and can therefore be used to probe the state of the photochromic switch. The probing wavelength now interrogates the plasmonic structure, not the molecular film, and can thus be conveniently placed in a transparent spectral range, e.g., the near-infrared. We find good agreement between experiments and numerical simulations with regard to spectral signatures of the plasmon resonance.

Response Current from Spin-Vortex-Induced Loop Current System to Feeding Current

The spin-vortex-induced loop current (SVILC) is a loop current generated around a spin-vortex formed by itinerant electrons. It is generated by a U(1) instanton created by the single-valued requirement of wave functions with respect to the coordinate, and protected by the topological number, “winding number”. In a system with SVILCs, a macroscopic persistent current is generated as a collection of SVILCs. In the present work, we consider the situation where external currents are fed in the SVILC system and response currents are measured as spontaneous currents that flow through leads attached to the SVILC system. The response currents from SVILC systems are markedly different from the feeding currents in their directions and magnitude, and depend on the original current pattern of the SVILC system; thus, they may be used in the readout process in the recently proposed SVILC quantum computer, a quantum computer that utilizes SVILCs as qubits. We also consider the use of the response current to detect SVILCs.

Evaluation of current sensitivity of quantum flux parametron

Current sensitivity of a quantum flux parametron (QFP) was evaluated by measuring gray zone width on the basis of both circuit simulation and measurements, for superconducting sensing systems composed of a superconducting sensor array and superconducting read-out and signal processing circuits. Simulation results indicate a narrow gray zone width can be obtained by decreasing inductances comprising the QFP. Moreover, both high-sensitivity and low-power operation of the QFP can be realized by using optimized circuit parameters with an excitation current that has long rise time. A gray zone width of approximately 0.5 μA, which is smaller than that of the Josephson current comparator based on a single flux quantum circuit, was obtained experimentally, using a trapezoidal excitation current with rise time of 50 μs. These results indicate the QFP is promising for the read-out circuit in superconducting sensing systems, due to its high sensitivity and low power consumption.

Optimization of the Microwave Properties of the Kinetic-Inductance Bolometer (KIBO)

Silicon nitride membrane based cryogenic bolometers exhibit high sensitivity and enable ultra-sensitive detector applications. Multi-pixel instruments were already introduced as devices for submillimeter-wave imaging. Nevertheless, the numbers of pixels are limited by the readout process which is typically a time-division multiplexing or code-division multiplexing technique. To overcome this challenge, a replacement of the transition-edge sensor as thermometer by a lumped-element resonance circuit seems to be a promising solution. Therefore, one can benefit from the intrinsic capability of frequency-division multiplexing that allows the readout of large detector arrays simultaneously and in real-time. The number of pixels is then limited by the available readout bandwidth and the quality factors of each individual resonance circuit. We successfully demonstrated, based on our feasibility study, the principal operation of such a device, what we call kinetic-inductance bolometer (KIBO). But the overall performance of the achievable noise-equivalent power (NEP) was limited by implementation and operation temperature of KIBO. Therefore, improved KIBO designs were developed and fabricated with niobium thin-film technology. In this paper, we describe the improvement procedure and estimate the expected NEP value.

Computational analysis of thermoluminescence glow curves from thin layer dosemeters

The Monitoring Service at the Materialprüfungsamt Nordrhein-Westfalen in Dortmund develops a new dosemeter system for large-scale individual dose monitoring. The dosemeters make use of thermoluminescence light from a thin layer of LiF:Mg,Ti. In the large-scale routine dosimetry service, a high number of dosemeters have to be evaluated on a monthly basis, which requires a fast readout. Therefore, thermoluminescence is stimulated by exponential heating of the dosemeters.The main quantity of interest to obtain from a dosemeter is the irradiation dose. Since the data comes in the form of thermoluminescence glow curves, their analysis offers the possibility to extract more information from the data than the irradiation dose, e.g. the fading time. In addition, such an analysis can reduce the uncertainties of the reconstructed irradiation dose, especially for low irradiation doses.Because it is not possible to measure the temperature of the dosemeter during the readout process, the recorded time-dependent glow curves have to be converted to temperature-dependent glow curves before the analysis.

Improvement of the TLD dose calculation by application of an individual residual dose correction

Thermoluminescence (TL) detectors store energy from ionizing radiation, this energy is then released in the readout process by heating the detector. The light that is emitted can be recorded in the form of a glow curve (GC), from which the dose can be calculated. The TL detectors discussed in this paper are made of LiF:Mg,Ti and produced by Thermo Scientific under the name TLD-100. They are used in the routine dosimetry process of Seibersdorf Laboratories, where several thousand dosimeters need to be read every month. This paper investigates a method to improve the measurement accuracy by applying a detector-specific residual dose correction. Opposed to the current practice, where a constant value is subtracted to correct for an always present small zero-dose and a contribution from the natural background radiation, the method introduced in this paper uses a second readout immediately following the original readout to calculate and subtract a residual dose, which is then different for each detector. It will be shown that this decreases the standard deviation of detectors irradiated with the same dose, as well as allowing for a possibly smaller lower limit of detection.

TLD and OSLD dosimetry systems for remote audits of radiotherapy external beam calibration

The Imaging and Radiation Oncology Core QA Center in Houston (IROC-H) performs remote dosimetry audits of more than 20,000 megavoltage photon and electron beams each year. Both a thermoluminescent dosimeter (TLD-100) and optically stimulated luminescent dosimeter (OSLD; nanoDot) system are commissioned for this task, with the OSLD system being predominant due to the more time-efficient read-out process. The measurement apparatus includes 3 TLD or 2 OSLD in an acrylic mini-phantom, which are irradiated by the institution under reference geometry. Dosimetry systems are calibrated based on the signal-to-dose conversion established with reference dosimeters irradiated in a Co-60 beam, using a reference dose of 300 cGy for TLD and 100 cGy for OSLD. The uncertainty in the dose determination is 1.3% for TLD and 1.6% for OSLD at the one sigma level. This accuracy allows for a tolerance of ±5% to be used.

Performance of Scintillation Pixel Detectors with MPPC Read-out and Digital Signal Processing

We have assembled and tested a system of 2 detector modules containing Lutetium Fine Silicate scintillator pixels in 4 × 4 matrix, read out by multi-pixel photon counter arrays with the matching element size. The amplified signals were acquired using fast digitizers and stored for offline analysis. Using two different approaches, we have determined the single crystal relative energy resolution at 511 keV to be 14% and 12%. The coincidence time resolution has been tested using the digital constant fraction triggering and the leading edge method, and the resulting resolutions are 1.6 ns and 0.5 ns, respectively.

Tunable Luminescence Contrast of Na0.5Bi4.5Ti4O15:Re (Re = Sm, Pr, Er) Photochromics by Controlling the Excitation Energy of Luminescent Centers.

High luminescent switching contrast of photochromic materials is extremely important in improving the sensitivity and resolution of optical switches and high-density optical data storage devices. To date, conventional methods, such as tuning absorption and emission bands based on electron or resonance energy transfer mechanisms in well-known organic photochromic molecules or compounds, have routinely been adopted to tune luminescent switching behavior. However, these strategies and mechanisms are not effectively applied to luminescence switching in inorganic materials because their crystal structures differ strongly from those of organic materials. In this paper, we report a new method to significantly tune the luminescent switching contrast by modifying the excitation energy of luminescent centers in a newly synthesized photochromism material: Na0.5Bi4.5Ti4O15:Re (Re = Sm, Pr, Er). A significant enhancement of luminescence switching contrast was achieved when the luminescent centers were excited by low energy photons at a given irradiation wavelength, intensity, and time, compared with high excitation energy photons. The trend "the lower the excitation energy, the higher the luminescence switching contrast" is universal in different rare earth ion-doped Na0.5Bi4.5Ti4O15 ferroelectrics. The changes in the luminescent switching contrast based on excitation energy are ascribed to nonradiative energy transfer from the luminescent center to the color center by dipole-dipole interactions according to Dexter theory. This possible utilization of excitation energy at lower energy levels is usually less destructive to both information recording and the recording material itself during luminescent readout processes while achieving higher luminescence switching contrast.

Theoretical Analysis of Gap Potential Functions and Corner Saturation in 2-D, Symmetric Magnetic Recording Heads With Tilted Gap Corners

The 2-D, semi-infinite symmetrical head with gap corner angle $\alpha $ and in the absence of a soft underlayer was postulated in the early history of magnetic recording to develop the field theory necessary for modeling and understanding the record and readout processes. Practical and mathematical considerations limited the theory of this general head structure to corner angles $\alpha = 90^{\circ }$ (right-angled head) and $\alpha = 0^{\circ }$ (“thin” gap head). Thus, explicit and analytical solutions for the gap potential function and its Fourier transform (necessary for determining the fields beyond the head surface) as functions of corner angle for symmetrical heads remain unavailable. Moreover, saturation in the gap corners associated with the reduction of the gap corner angle is not well understood and characterized. In this paper, the scalar magnetic potential of a single 2-D corner is derived exactly, and the superposition of two corner potentials was then used to derive an approximate analytical expression for the gap potential function of 2-D symmetrical heads with arbitrary corner angle. The derived expressions for the potentials and fields were in excellent agreement with exact analytical solutions and with finite-element solutions for all $\alpha \leq 90^{\circ }$ . The derived expressions were also shown to predict accurately the surface potentials of other symmetrical head structures, including the tilted pole head, the parallel plate head, and the tilted plate head. An analytical approximation for the Fourier transform of the surface field for the 2-D symmetrical head was derived, showing the shift in the spectral gap nulls toward longer wavelengths with reducing gap corner angle. Systematic finite-element calculations of the static vector potential for the 2-D symmetrical head were carried out using a nonlinear B-H core material model for different driving fields and corner angles. Corner saturation was characterized by the driving fields that yield 10% root-mean-square deviation from the linear material response. The simulations correctly predicted the known saturation driving field $M_{s}$ /2 for right-angle heads ( $M_{\mathrm {s}}$ is the core saturation magnetization), and revealed a generalization for all $\alpha \leq 90^{\circ }$ in the form of the exponential dependence $aM_{s}\exp (b\alpha )$ , where the free parameters $a$ and $b$ were determined from fitting to the finite-element simulations for both field maxima and their gradients.

System-on-Chip Considerations for Heterogeneous Integration of CMOS and Fluidic Bio-Interfaces.

CMOS chips are increasingly used for direct sensing and interfacing with fluidic and biological systems. While many biosensing systems have successfully combined CMOS chips for readout and signal processing with passive sensing arrays, systems that co-locate sensing with active circuits on a single chip offer significant advantages in size and performance but increase the complexity of multi-domain design and heterogeneous integration. This emerging class of lab-on-CMOS systems also poses distinct and vexing technical challenges that arise from the disparate requirements of biosensors and integrated circuits (ICs). Modeling these systems must address not only circuit design, but also the behavior of biological components on the surface of the IC and any physical structures. Existing tools do not support the cross-domain simulation of heterogeneous lab-on-CMOS systems, so we recommend a two-step modeling approach: using circuit simulation to inform physics-based simulation, and vice versa. We review the primary lab-on-CMOS implementation challenges and discuss practical approaches to overcome them. Issues include new versions of classical challenges in system-on-chip integration, such as thermal effects, floor-planning, and signal coupling, as well as new challenges that are specifically attributable to biological and fluidic domains, such as electrochemical effects, non-standard packaging, surface treatments, sterilization, microfabrication of surface structures, and microfluidic integration. We describe these concerns as they arise in lab-on-CMOS systems and discuss solutions that have been experimentally demonstrated.

Memristive Biosensors Integration With Microfluidic Platform

The integration of nanoscale sensors with microfluidic platforms is a powerful tool for the design of robust biosensing devices that present high reliability and the advantage of a quick data acquisition. In addition, microfluidic based lab-on-a-chip sensors require minute amounts of clinical samples and cancer biosensing products. However, the integration of nanostructures in such more complex configurations may significantly complicate the electrical readout process. The aim of the present work is to develop improved devices for cancer prognosis based on nanofabricated Memristive Biosensors integrated for the first time with a microfluidic structure. The effective readout of the Memristive Biosensors electrical response is enabled through a series of specially designed metal line extensions realized accordingly in order to fully retain the sensing output signal.

Synthesis and photochromic properties of dithienylethenes axially coordinating with Mn(II)-porphyrins

A series of Mn(II)-porphyrinnic dithienylethenes were synthesized and the photochemical transitions between opening isomers and closed isomers upon the irradiation of ultraviolet light and visible light were detected by the UV–vis spectrometer. Furthermore, the open forms can emit fluorescence and the closed form can’t while irradiated in appropriate light that will not cause the optical chemical reaction. Therefore, a nondestructive readout process could be achieved for application in optical data storage.

High-density channel model and detection method for signal readout from super-resolution near-field structure discs

Although a readout method using the super-resolution near-field structure (super-RENS) effect can overcome diffraction limits, readout characteristics for greatly surpassed high-density conditions do not become clear, because a high-density channel function having a differential response property is superimposed on a normal readout function. We propose a high-density channel model to indicate the properties of the super-RENS effect directly. This model can be expressed as a differential response function using the finite impulse response (FIR) filter model. It expresses the super-RENS readout process, which is divided on the basis of recording densities such as high and normal Blu-ray Disc™ densities. We estimated the properties of super-RENS readout signals by comparison between theoretical expressions and experiments. Results show that good signal quality require readout signals having sharp peaks and smaller offsets. We also evaluated the channel model by adding an adaptive FIR filter and a Viterbi decoder by simulations. Results show that the super-RENS disc can achieve a fourfold higher recording density if the signal-to-noise ratio (S/N) is improved to 6 dB in the case of partial response (PR) (1 + D + D2).

A Touch Prediction and Window Sensing Strategy for Low-Power and Low-Cost Capacitive Multitouch Screen Systems

A new multitouch sensing strategy, named the Touch Prediction and Window Sensing (TPWS), is proposed and realized in this paper for projected capacitive touch screens. The detection procedures of TPWS are divided into two stages: a pre-sensing stage for predicting the possible touched regions, and a window sensing stage for obtaining the accurate touched positions. Since the measurements of the untouched sensing cells are reduced significantly, the TPWS strategy needs lower efforts on signal readout and data processing than the traditional strategies. A prototype system was designed and realized, which consists of three identical 48-channel readout chips, a 15-in capacitive touch screen, and a commercial host processor. The readout chip is specially designed for the TPWS strategy using $\hbox{0.13}~\mu\hbox{m}$ 1.8 V/5 V CMOS process. The measurement results show that, the total power consumption of the system is only about 65 mW with a power supply of 5 V, and the reporting rate of the system achieves 500 Hz for no touches and 83 Hz for ten touches. The area of the readout chip is only 0.087 $ ~\hbox{mm}^{2}$ per sensing channel. The proposed TPWS strategy can be used to realize low-power and low-cost multitouch screen system, and it is especially efficient for large-sized screen.

PSA Detection with Femtomolar Sensitivity and a Broad Dynamic Range Using SERS Nanoprobes and an Area-Scanning Method

Recently, surface-enhanced Raman scattering (SERS)-based immunoassays (SIA) have drawn much attention as diagnostic tools with large multiplex capacity and high sensitivity. However, several challenges—such as a low reproducibility, a time-consuming read-out process, and limited dynamic range—remain. In this study, we report a reliable and sensitive SIA platform for prostate specific antigen (PSA) detection. Reliability and sensitivity were achieved by two approaches: (1) well-established SERS probes, so-called SERS dots that have high sensitivity (single particle detection) and little particle-to-particle variation in SERS intensity; and (2) a whole area-scanning readout method for rapid and reliable chip analysis rather than point scanning. As a feasibility test, PSA could be detected with high sensitivity (ca. 0.11 pg/mL, 3.4 fM LOD), with a wide dynamic range (0.001–1000 ng/mL). Thus, the developed platform will facilitate development of reliable immunoassays with high sensitivity and a wide dynamic r...

Fast structured illumination microscopy using rolling shutter cameras

Spatial light modulators (SLM) update in a synchronous manner, whereas the data readout process in fast structured illumination systems is usually done using a rolling shutter camera with asynchronous readout. In structured illumination microscopy (SIM), this leads to synchronization problems causing a speed limit for fast acquisition. In this paper we present a configuration to overcome this limit by exploiting the extremely fast SLM display and dividing it into several segments along the direction of the rolling shutter of the sCMOS camera and displaying multiple SLM frames per camera acquisition. The sCMOS runs in continuous rolling shutter mode and the SLM keeps the readout-line always inside a dark region presenting different SIM patterns before and after the readout/start-exposure line.Using this approach, we reached a raw frame rate of 714 frames per second (fps) resulting in a two-beam SIM acquisition rate of 79 fps with a region of interest (ROI) of 16.5 × 16.5 μm2.

Development of new data acquisition system for COMPASS experiment

This paper presents development and recent status of the new data acquisiton system of the COMPASS experiment at CERN with up to 50 kHz trigger rate and 36 kB average event size during 10 second period with beam followed by approximately 40 second period without beam. In the original DAQ, the event building is performed by software deployed on switched computer network, moreover the data readout is based on deprecated PCI technology; the new system replaces the event building network with a custom FPGA-based hardware. The custom cards are introduced and advantages of the FPGA technology for DAQ related tasks are discussed. In this paper, we focus on the software part that is mainly responsible for control and monitoring. The most of the system can run as slow control; only readout process has realtime requirements. The design of the software is built on state machines that are implemented using the Qt framework; communication between remote nodes that form the software architecture is based on the DIM library and IPBus technology. Furthermore, PHP and JS languages are used to maintain system configuration; the MySQL database was selected as storage for both configuration of the system and system messages. The system has been design with maximum throughput of 1500 MB/s and large buffering ability used to spread load on readout computers over longer period of time. Great emphasis is put on data latency, data consistency, and even timing checks which are done at each stage of event assembly. System collects results of these checks which together with special data format allows the software to localize origin of problems in data transmission process. A prototype version of the system has already been developed and tested the new system fulfills all given requirements. It is expected that the full-scale version of the system will be finalized in June 2014 and deployed on September provided that tests with cosmic run succeed.

Large-Area Microphone Array for Audio Source Separation Based on a Hybrid Architecture Exploiting Thin-Film Electronics and CMOS

We present a system for reconstructing-independent voice commands from two simultaneous speakers, based on an array of spatially distributed microphones. It adopts a hybrid architecture, combining large-area electronics (LAE), which enables a physically expansive array ( ${>} 1\text{ m}$ width), and a CMOS IC, which provides superior transistors for readout and signal processing. The array enables us to: 1) select microphones closest to the speakers to receive the highest SNR signal; 2) use multiple spatially diverse microphones to enhance robustness to variations due to microphones and sound propagation in a practical room. Each channel consists of a thin-film transducer formed from polyvinylidene fluoride (PVDF), a piezopolymer, and a localized amplifier composed of amorphous silicon (a-Si) thin-film transistors (TFTs). Each channel is sequentially sampled by a TFT scanning circuit, to reduce the number of interfaces between the large-area electronics (LAE) and CMOS IC. A reconstruction algorithm is proposed, which exploits the measured transfer function between each speaker and microphone, to separate two simultaneous speakers. The algorithm overcomes 1) sampling-rate limitations of the scanning circuits and 2) sensitivities to microphone placement and directionality. An entire system with eight channels is demonstrated, acquiring and reconstructing two simultaneous audio signals at 2 m distance from the array achieving a signal-to-interferer (SIR) ratio improvement of ${\sim} 12\text{ dB}$ .

Investigation of Readout Cell Configuration and Parameters on Functionality and Stability of Bi-Directional RSFQ TFF

Considering the two main categories of rapid single flux quantum gates with destructive and nondestructive readout process, we have investigated the effects of readout cell topology and involved critical parameters on the proper functionality and stability of the states of the newly developed bidirectional T flip-flops (TFFs). It is observed that instabilities and fluctuations in the state of the gate (memory of TFF) after each transition determine the minimum time intervals between the clock pulses set by the ac bias current, further limiting the ultimate operation frequency of the circuits. The absolute values of the current levels of the junctions at each state, which play an important role in the behavior of the cell, are studied, and their variations over several consequent pulses are stabilized by optimizing the cell parameters. The appropriate values of the circuit and junction parameters are found, resulting in the optimum operation of the circuit for having the best margins possible. We report on the investigated circuit topology and parameter optimizations of the readout circuit of the considered bidirectional TFF.