Search

Lensless microscopy requires the simplest possible configuration, as it uses only a light source, the sample and an image sensor. The smallest practical microscope is demonstrated here. In contrast to standard lensless microscopy, the object is located near the lighting source. Raster optical microscopy is applied by using a single-pixel detector and a microdisplay. Maximum resolution relies on reduced LED size and the position of the sample respect the microdisplay. Contrarily to other sort of digital lensless holographic microscopes, light backpropagation is not required to reconstruct the images of the sample. In a mm-high microscope, resolutions down to 800 nm have been demonstrated even when measuring with detectors as large as 138 μm × 138 μm, with field of view given by the display size. Dedicated technology would shorten measuring time., This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 737089 and from the Ministry of Science and Innovation, the Spanish State Research Agency and the European Regional Development Fund through project PID2019-105714RB-I00.

Belle II DEPFET, PXD, and SVD Collaborations: et al., The Belle II experiment comes with a substantial upgrade of the Belle detector and will operate at the SuperKEKB energy-asymmetric ee collider with energies tuned to ϒ(4S) resonance s=10.588 GeV. The accelerator has successfully completed the first phase of commissioning in 2016 and the first electron–positron collisions in Belle II took place in April 2018. Belle II features a newly designed silicon vertex detector based on DEPFET pixel and double-sided strip layers. Currently, a subset of the vertex detector is installed (Phase 2 of the experiment). Installation of the full detector (Phase 3) will be completed by the end of 2018. This paper describes the Phase 2 arrangement of the Belle II silicon vertex detector, with focus on the interconnection of detectors and their integration with the software framework of Belle II. Alignment issues are discussed based on detector simulations and first acquired data., This work is supported by MSCA-RISE, European Union project JENNIFER (EU grant n. 644294), MEXT, Japan, WPI, and JSPS (Japan); ARC (Australia); BMWFW (Austria); MSMT, Czech Republic, GAUK 404316 (Czech Republic); AIDA-2020 (Germany); DAE, India and DST (India); INFN (Italy); NRF-2016K1A3A7A09005605 and RSRI (Korea); MNiSW (Poland); Federal Ministry of Education and Research (BMBF, Germany); and MINECO, Spain grant FPA2015-71292-C2-1-P (Spain).

In this work we present a new microscope based on Nano-illumination microscopy (NIM), i.e., an innovative technique based on a 2D array of nano-Light-Emitting Diodes (LEDs) used to illuminate a sample. The key point of this method is that the pitch of the LED array fixes the spatial resolution. So, potentially, with LED pitches lower than the diffraction limit, super resolution could be achieved. While nanometer sized LEDs are not available yet, we present a prototype based on optical downscaling of a single 5µm lateral size LED. Extended Field-of-View (FOV) is obtained by mechanical movement with nanopositioners. Aspects of NIM microscopy such as its size, its flexibility in the sensing hardware or its potential for fluorescence, make it a perfect candidate to enhance emerging sensing applications in different fields, but especially life science (medical imaging, genomics, ...). We demonstrate the possibilities of the NIM technique with patterns as well as with biological samples.

Belle-II DEPFET and PXD Collaboration: et al., The Belle II experiment at the SuperKEKB energy-asymmetric e+ e- collider has completed a series of substantial upgrades and started collecting data in 2019. The experiment is expected to accumulate a data set of 50 ab−1 to explore new physics beyond the Standard Model at the intensity frontier. The pixel detector (PXD) of Belle II plays a key role in vertex determination. It has been developed using the DEpleted P-channel Field Effect Transistor (DEPFET) technology, which combines low power consumption in the active pixel area and low intrinsic noise with a very small material budget. In this paper, commissioning and performance of the PXD measured with first collision data are presented., This work is supported by MEXT, Japan, WPI, Japan, and JSPS (Japan); MSMT, GAUK 404316, MSCA-RISE project JENNIFER-2 (EU grant n. 822070) (Czech Republic); Federal Ministry of Education and Research (BMBF, Germany) and MINECO, Spain grant FPA2015-71292-C2-1-P (Spain).

The recent advances in chip-size microscopy based on optical scanning with spatially resolved nano-illumination light sources are presented. This new straightforward technique takes advantage of the currently achieved miniaturization of LEDs in fully addressable arrays. These nano-LEDs are used to scan the sample with a resolution comparable to the LED sizes, giving rise to chip-sized scanning optical microscopes without mechanical parts or optical accessories. The operation principle and the potential of this new kind of microscope are analyzed through three different implementations of decreasing LED dimensions from 20 µm down to 200 nm.

MicroLED arrays with the capability of switching each pixel separately with high frequency can serve as structured micro-illumination light engines for applications in sensing, optogenetics, microscopy and many others. We describe a scalable chip process chain for the fabrication of passive-matrix microLED arrays, which were integrated with PCB-based driving electronics. The arrays were produced by deep-etching of conventional planar LED structures on sapphire, followed by filling and planarization steps. The pixel resolution lies in the range of 254 to 2540 pixels-per-inch (ppi), the arrays consist of 32 x 32 pixels. Optical output powers up to 50 µW per pixel were measured. In comparison to CMOS-based approaches, the presented technology is a simplified strategy to produce microLED arrays with high pixel counts.

GaN-based light emitting diodes (LEDs) have been shown to effectively operate down to nanoscale dimensions, which allows further downscaling the chip-based LED display technology from micro- to nanoscale. This brings up the question of what resolution limit of the illumination pattern can be obtained. We show two different approaches to achieve individually switchable nano-LED arrays. We evaluated both designs in terms of near-field spot size and optical crosstalk between neighboring pixels by using finite difference time domain (FDTD) simulations. The numerical results were compared with the performance data from a fabricated nano-LED array. The outcome underlines the influence of geometry of the LED array and materials used in contact lines on the final illumination spot size and shape.

Tiny lights enable molecular-scale imaging Arrays of nanoscale light-emitting diodes (LEDs) offer an energy-efficient means for achieving microscopic imaging with resolution below the diffraction limit. Microscale LEDs are already poised to have a transformative impact on display technology, but it remains challenging to construct arrays of individually controllable LEDs at the nanometer scale. Daria Bezshlyakh of the Technische Universität Braunschweig in Germany and colleagues have developed a fabrication approach that enabled them to manufacture a compact super-resolution imaging system based on such arrays. Their device employs gallium nitride nano-LEDs that generate precisely structured patterns of illumination, which make it possible to image specimens at spatial resolutions smaller than the wavelength of light. Based on the performance and stability of this initial prototype, the authors conclude that similar devices could offer a promising platform for future molecular imaging applications.

In lensless microscopy, spatial resolution is usually provided by the pixel density of current digital cameras, which are reaching a hard-to-surpass pixel size / resolution limit over 1 µm. As an alternative, the dependence of the resolving power can be moved from the detector to the light sources, offering a new kind of lensless microscopy setups. The use of continuously scaled-down Light-Emitting Diode (LED) arrays to scan the sample allows resolutions on order of the LED size, giving rise to compact and low-cost microscopes without mechanical scanners or optical accessories. In this paper, we present the operation principle of this new approach to lensless microscopy, with simulations that demonstrate the possibility to use it for super-resolution, as well as a first prototype. This proof-of-concept setup integrates an 8 × 8 array of LEDs, each 5 × 5 μm2pixel size and 10 μmpitch, and an optical detector. We characterize the system using Electron-Beam Lithography (EBL) pattern. Our prototype validates the imaging principle and opens the way to improve resolution by further miniaturizing the light sources. © 2020 Optical Society of America under the terms of theOSA Open Access Publishing Agreement

The Belle II experiment features a substantial upgrade of the Belle detector and will operate at the SuperKEKB energy-asymmetric e+e− collider at KEK in Tsukuba, Japan. The accelerator completed its first phase of commissioning in 2016, and the Belle II detector saw its first electron-positron collisions in April 2018. Belle II features a newly designed silicon vertex detector based on double-sided strip layers and DEPFET pixel layers. A subset of the vertex detector was operated in 2018 to determine background conditions (Phase 2 operation). The collaboration completed full detector installation in January 2019, and the experiment started full data taking. This paper will report on the final arrangement of the silicon vertex detector part of Belle II with a focus on online monitoring of detector conditions and data quality, on the design and use of diagnostic and reference plots, and on integration with the software framework of Belle II. Data quality monitoring plots will be discussed with a focus on simulation and acquired cosmic and collision data.

A miniature internet of things (IoT)-based point-of-care testing (PoCT) fluorescence reader, able to perform both intensity and time-resolved measurements of different fluorescent tags, is presented. This low cost platform has been conceived for performing tests in low-resource and remote settings, displaying versatile performance and yet simple operation. It consists on an external case of 43 × 30 × 42 mm3 (built in a 3D-printer) where all the elements are fixed, including some basic optics (3 lenses and 2 filters), a laser diode and a custom designed Single-Photon Avalanche Diodes (SPADs) camera. Both, the laser and the camera are controlled by a Field Programmable Gate Array (FPGA) with IoT capabilities. The PoCT was validated by detecting Plasmodium antigen in a fluorescent enzyme-linked immunosorbent assay (ELISA) using a fluorescence substrate. The results were compared to those provided in parallel by two commercial fluorescent plate readers. As it will be shown, the PoCT fluorescent readout was more sensitive than its colorimetric counterpart. Furthermore, the PoCT displayed similar signal trends and levels of detection than the bulkier and more expensive commercial fluorescence plate readers. These results demonstrate that the PoCT platform developed could bring the performance of central laboratory assay techniques closer to the end-user level.

We describe the integration of techniques and technologies to develop a Point-of-Care for molecular diagnosis PoC-MD, based on a fluorescence lifetime measurement. Our PoC-MD is a low-cost, simple, fast, and easy-to-use general-purpose platform, aimed at carrying out fast diagnostics test through label detection of a variety of biomarkers. It is based on a 1-D array of 10 ultra-sensitive Single-Photon Avalanche Diode (SPAD) detectors made in a 0.18 &mu, m High-Voltage Complementary Metal Oxide Semiconductor (HV-CMOS) technology. A custom microfluidic polydimethylsiloxane cartridge to insert the sample is straightforwardly positioned on top of the SPAD array without any alignment procedure with the SPAD array. Moreover, the proximity between the sample and the gate-operated SPAD sensor makes unnecessary any lens or optical filters to detect the fluorescence for long lifetime fluorescent dyes, such as quantum dots. Additionally, the use of a low-cost laser diode as pulsed excitation source and a Field-Programmable Gate Array (FPGA) to implement the control and processing electronics, makes the device flexible and easy to adapt to the target label molecule by only changing the laser diode. Using this device, reliable and sensitive real-time proof-of-concept fluorescence lifetime measurement of quantum dot QdotTM 605 streptavidin conjugate is demonstrated.

Time-resolved fluorescence measurement is extraordinarily powerful in the analysis of substances due to its effectiveness in eliminating measurement artifacts. Some fluorescence measurements are still conducted on CMOS chips with the decay times determined after reading the data off the chip and fitting the fluorescence decay histogram. We present a novel approach in which an analog CMOS chip divides the fluorescence decay time into slices and classifies the photons according to their arrival times at a CMOS SPAD sensor. The chip was fabricated in a 1P6M 0.18 μm HV-CMOS process. The slice timings can be tailored from 168 ps to 4.9 ns, covering most fluorescence decay times. 9 timing windows are generated per pixel that count up to 13 b each, with a resolution of 0.16 mV/photon, for a maximum output voltage of 1.3 V, in an area of 150 μm × 50 μm. Here, we report on the first practical application of this circuit, which integrates an array of 5 pixels in a single chip and has an excitation light and a microfluidic chip of up to 3 channels. This system could determine the decay time of quantum dots in 20 nl of solution. Thus, this paper could help in the development of a point-of-care device based on time-resolved fluorescence.

This work presents a first prototype for a new approach to microscopy: a system basing its resolving power on the light emitters instead of the sensors, without using lenses. This new approach builds on the possibility of making LEDs smaller than current technology sensors, offering a new approach to microscopy we plan on developing towards superresolution. The microscope consists on a SPAD based camera, a 8x8 LED array with 5x5 μm LEDs distributed with a pitch of 10 μm, and discrete driving electronics to control them. We present simulations of the system, as well as the first microscope prototype implementing the method, and the results obtained through it.

Recent research into miniaturized illumination sources has prompted the development of alternative microscopy techniques. Although they are still being explored, emerging nano-light-emitting-diode (nano-LED) technologies show promise in approaching the optical resolution limit in a more feasible manner. This work presents the exploration of their capabilities with two different prototypes. In the first version, a resolution of less than 1 µm was shown thanks to a prototype based on an optically downscaled LED using an LED scanning transmission optical microscopy (STOM) technique. This research demonstrates how this technique can be used to improve STOM images by oversampling the acquisition. The second STOM-based microscope was fabricated with a 200 nm GaN LED. This demonstrates the possibilities for the miniaturization of on-chip-based microscopes., This work was partially supported by the European Union’s Horizon 2020 research and innovation program under grant agreement No. 737089—ChipScope.

Fluorescence-based techniques are amongst the most widely used methods in molecular analysis in life science with multiple applications in clinical analysis and biomedical diagnosis. Considerable efforts have been directed toward the miniaturization of the fluorescence-based instruments, in an effort to reduce both cost and form factor for point of care (PoC) applications, but at the expense of increasing the complexity of the system or losing sensitivity. A new technology is being developed to build a PoC device based on fluorescence lifetime detection for molecular diagnosis with a sensitivity comparable to the bulky optical instruments and with a diagnosis time of a few seconds. Our PoC is a low-cost, simple, fast and easy to use general purpose platform, aimed at carrying out a fast diagnostics test through label detection of a variety of biomarkers. The system is designed to eliminate the optical requirements associated with traditional fluorescence lifetime instruments. With an array of ultra-sensitive detectors based on CMOS SAPD (single photo avalanche diode) technology along a custom microfluidic polydimethyl-siloxane (PDMS) cartridge on top of the sensor to insert the sample. The proximity of the sample and the SPAD sensor conjointly with the gate mode operation of the sensors, makes the use of lenses and optical filters unnecessary. The device is operated in Time Correlated Single Photon Counting (TCSPC), measuring the time of arrival of the photons after excitation of the fluorescence with a nanosecond laser diode. The sensor, which is extremely sensitive to light in the rage from 400 to 1000 nm, and of ultra-high speed, works in gated mode, which makes it practically unaffected by the intrinsic noise. The system has been characterized with several concentrations of fluorescent quantum dots (Qdot®605 streptavidin conjugate from Life Technologies) as proof-of-concept for lifetimes of several nanoseconds. The lifetime of the quantum dots is 35 ns, and is measured in only 15 seconds.

It is well known that avalanche photodiodes operated in the Geiger mode above the breakdown voltage offer a virtually infinite gain and time accuracy in the picosecond range that can be used for single photon detection. However, their performance in particle detection still remains unexplored. In this contribution, we are going to expose different steps that we have taken in order to prove the efficiency of the Geiger mode avalanche photodiodes in the aforementioned field. In particular, we will present a setup for the characterization of these sensors in a test beam. The expected results of the test beam at DESY and CERN have been simulated with Geant4 and will also be exposed.

This work presents a low cost fluorescence life time measurement system, aimed at carrying out fast diagnostic tests through label detection in a portable system so it can be used in a medical consultation, within a short time span. The system uses Time Correlated Single Photon Counting (TCSPC), measuring the arrival time of individual photons and building a histogram of those times, showing the fluorescence decay of the label which is characteristic of each fluorescent substance. The system is implemented using a Xilinx FPGA which controls the experiment and includes a Time to Digital Converter (TDC) to perform measurements with a resolution in the order of tenths of picoseconds. Also included are a laser diode and the driving electronics to generate short pulses as well as a HV-CMOS implemented Single Photon Avalanche Diode (SPAD) as a high gain sensor. The system is entirely configurable so it can easily be adapted to the target label molecule and measurement needs. The histogram is constructed within the FPGA and can then be read as convenient. Various performance parameters are also shown, as well as experimental measurements of a quantum dot fluorescence decay as a proof of concept.

This paper addresses the circuit implementation challenges resulting from the integration of a therapeutic clip in a magnetically maneuverable wireless capsule intended for colonoscopy. To deal with the size constraints typical of a capsule endoscope, an Application Specific Integrated Circuit (ASIC) has been designed specifically to habilitate the release of the therapeutic clip. The ASIC is a complete System on Chip (SoC) that incorporates a circuit for the low power release of the clip, thus overcoming the limitations of the power supply system. With a size of 14[Formula: see text]mm2, the ASIC can be incorporated in practically any capsule endoscope, consuming only an idle-state power of 1.5[Formula: see text]mW.

This work reports on a novel effort to use Avalanche PhotoDiodes (APDs) to construct an active pixel detector for charged particles in collider experiments. A dual-beam Focused Ion Beam setup was used to characterize the response of the device. Results on the sensitivity of the guard structures separating pixels are compared to a detailed Monte Carlo simulation. These results suggest that, through control of the doping concentration, devices with a much improved fill factor can be achieved. A new technology is proposed that could elevate the fill factor to 100%.

Electron beams of Scanning Electron Microscope (SEM) and dual-beam Focused Ion Beam (FIB) have been used to characterize a Geiger-mode Avalanche Photodiode (GAPD) array. The main advantage of those electron beams is the spot-size unprecedent resolution compared to the laser beams typically used for the characterization of optical imagers. Operation mode is also different, as instead of generating electron-hole pairs due to photon absorption, electrons are generated by the high energy injected electrons. The GAPDs used have been fabricated with a conventional CMOS process. They are excellent for the purpose of this experiment because of their very high intrinsic gain and speed, giving rise, when properly biased, to a large output signal as a consequence of detected photons or ionizing particles. The detected counts due to injected particles have been correlated with Montecarlo simulations (Penelope) of the injected charge in the interaction region.

Point of care devices for the early diagnosis of current relavant diseases of our society require novel miniature and very effective devices. This contribution focuses on the description of behavioral models aimed to develop custom readout Application-Specific Integrated Circuits (ASICs) for the measurement of Fluorescence and Fluorescence life-time of target substances. The well suited for the ASIC development Verilog-A behavioral description language is used to describe the sensor, an ultra sensitive Single Photon Avalanche Diode (SPAD) fabricated in a conventional CMOS process, and the fluorescence signal.

The electronics for monolithically integrated gas sensor arrays fabricated using a compatible CMOS process have been developed. Circuitry includes the heater driver for temperature control and an interface circuit for inspection of the four sensors in the array. The operating temperature of the sensing resistors is between 200° and 400°C. The proposed temperature controller is capable of regulating the temperature of a 2100 × 2100 μm hotplate up to 400°C with a resolution of 2°C with 5 V supply voltage. A readout circuit based on a ring-oscillator has been included to measure the sensing resistance change upon gas exposure over a high dynamic range. Because it is robust, small, low priced and offers future capabilities with adequate signal processing, the system would be able to cover most of today's gas sensor markets.

This work presents a low cost fluorescence life time measurement system, aimed at carrying out fast diagnostic tests through label detection in a portable system so it can be used in a medical consultation, within a short time span. The system uses Time Correlated Single Photon Counting (TCSPC), measuring the arrival time of individual photons and building a histogram of those times, showing the fluorescence decay of the label which is characteristic of each fluorescent substance. The system is implemented using a Xilinx FPGA which controls the experiment and includes a Time to Digital Converter (TDC) to perform measurements with a resolution in the order of tenths of picoseconds. Also included are a laser diode and the driving electronics to generate short pulses as well as a HV-CMOS implemented Single Photon Avalanche Diode (SPAD) as a high gain sensor. The system is entirely configurable so it can easily be adapted to the target label molecule and measurement needs. The histogram is constructed within the FPGA and can then be read as convenient. Various performance parameters are also shown, as well as experimental measurements of a quantum dot fluorescence decay as a proof of concept.

In this paper, an ASIC fabricated in 180 nm CMOS technology from AMS with the very front-end electronics used to readout LGAD sensors is presented as well as its experimental results. The front-end has the typical architecture for Si-strip readout, i.e., preamplification stage with a Charge Sensitive Amplifier (CSA) followed by a CR-RC shaper. Both amplifiers are based on a folded cascode structure with a PMOS input transistor and the shaper only uses passive elements for the feedback stage. The CSA has programmable gain and a configurable input stage in order to adapt to the different input capacitance of the LGAD sensors (pixelated, short and long strips) and to the different input signal (depending on the gain of the LGAD). The fabricated prototype has an area of 0.865 mm × 0.965 mm and includes the biasing circuit for the CSA and the shaper, 4 analog channels (CSA+shaper) and programmable charge injection circuits included for testing purposes. Noise and power analysis performed during simulation fixed the size of the input transistor to W/L = 860 μm/0.2 μm. The shaping time is fixed by design at 1 us and, in this ASIC version, the feedback elements of the shaper are passive, which means that the area of the shaper can be reduced using active elements in future versions. Finally, the different gains of the CSA have been selected to maintain an ENC below 400 electrons for a detector capacitor of 20 pF, with a power consumption of 150 μ W per channel.

The role and activity of catalytic additives on solid-state gas sensors are determined by the additive chemical state, aggregation form and interaction with the semiconductor oxide. All these parameters depend on the technological steps involved in the element introduction and the treatments applied to the sensor material. The aim of this work is to analyse the influence of the additive introduction procedure on the gas sensor performance. In order to achieve this objective, two sets of different palladium, platinum or gold modified tin oxide materials have been prepared. In a first set of samples, additives were introduced by impregnation of the previously thermally stabilised oxide. In the second set, catalyst addition was carried out before any thermal treatment was applied. The study of the catalytically modified materials, calcined at different treatment temperatures between 250 and 1000°C, has been performed by means of HRTEM, XRD, XPS, and Raman spectroscopy. The influence of both processes on additive surface concentration, chemical state, nanoparticle growth and resistivity values are presented and discussed. Moreover, electrical characterisation of the sensors prepared from these materials has been carried out.

A 130 nm mixed (analog and digital) CMOS chip intended to read silicon strip detectors for future linear collider experiments was developed. Currently under testing, this chip has been optimized for a silicon micro-strip tracking device. It includes 88 channels of a full analog signal processing chain with the corresponding digital control and readout. Every analog channel includes (i) a low noise charge amplifier and integration with long pulse shaping, (ii) an eight by eight positions analog sampler for both storing successive events and reconstructing the full pulse shape, and (iii) a sparsifier performing analog sum of three adjacent inputs to decide whether there is signal or not. The whole system is controlled by the digital part, which allows configuring all the reference currents and voltages, drives the control signals to the analog memories, records the timing and channel information and subsequently performs the conversion to digital values of samples. The total surface of the circuit is 10×5 mm2, with each analog channel occupying an area of 105×3500 μm2, and the remaining space of about 9000×700 μm2 being filled by the analog channels on the silicon.

The effects of the introduction of Pt and Pd by impregnation in sol–gel fabricated SnO 2 nanoparticles after calcination are reported in this paper. The differences in base resistance and sensitivity of sensors prepared using these powders are presented and explained — taking into account the chemical states of the metal additives and the generated surface states in the band gap of the SnO 2 .

The control of the technological steps such as calcination temperature and introduction of catalytic additives are accepted to be key points in the obtaining of improved sol–gel fabricated SnO2 thick film gas sensors with different sensitivity to NO2 and CO. In this work, after proving that the undoped material calcined at 1000°C is optimum for NO2 detection, grinding is added as third technological step for further modification of particle surface characteristics, allowing to reduce cross-sensitivity to CO. The influence of grinding on the base resistance and on the sensor signals to NO2 and CO is discussed in detail as a function of the structural differences of the sensing material.

In2O3 thin films prepared by sol–gel method make it possible to detect low levels (several hundreds ppb) of nitrogen dioxide in air. The possibility of grain size control in indium oxide-sensing layers has been established by using of two preparation methods—electron beam evaporation (EB) and sol–gel technique (SG). SG-prepared samples show smaller particles sizes (down to 5 nm), higher state of agglomeration, higher sensor resistance in air and higher response to NO2 in comparison to EB samples. Sol–gel technique leads to the preparation of polycrystalline indium oxide with particle sizes of about 5–6 nm after calcination at 400°C and 20 nm after calcination at 700°C. The initial state of particle agglomeration in initial indium hydroxide sol (IHS), stabilized with nitric acid, influences the structure and surface morphology of the resulting indium oxide. While the In2O3 layer prepared by using low agglomerated IHS is smooth and porous, In2O3 layers prepared from highly agglomerated IHS consist of two regions—thin layer and crystallite agglomerates in cubic and rectangular parallelepiped form. The last shows the best results in terms of NO2 sensitivity. Sensor resistance and NO2 sensitivity increase with the decrease of the grain sizes in In2O3.

This paper presents an analysis of the maximum achievable fill-factor by a pixel detector of Geiger-mode avalanche photodiodes with the Chartered 130 nm/Tezzaron 3D process. The analysis shows that fill-factors between 66% and 96% can be obtained with different array architectures and a time-gated readout circuit of minimum area. The maximum fill-factor is achieved when the two-layer vertical stack is used to overlap the non-sensitive areas of one layer with the sensitive areas of the other one. Moreover, different sensor areas are used to further increase the fill-factor. A chip containing a pixel detector of the Geiger-mode avalanche photodiodes and aimed to future linear colliders has been designed with the Chartered 130 nm/Tezzaron 3D process to increase the fill-factor.

Verilog-AMS is used to model the analog front-end of one channel in a multichannel readout ASIC for Silicon microstrips. The modellization in a behavioral language allowed to extract the requirements of the main components of the channel whithout needing to make the design at transistor level, thus decreasing the design time. This model of a complete channel will be used for further integration with the digital proces-sign electronics of the multichannel ASIC.

Photodiodes are the simplest but most versatile semiconductor optoelectronic devices. They can be used for direct detection of light, of soft X and gamma rays, and of particles such as electrons or neutrons. For many years, the sensors of choice for most research and industrial applications needing photon counting or timing have been vacuum-based devices such as Photo-Multiplier Tubes, PMT, and Micro-Channel Plates, MCP (Renker, 2004). Although these photodetectors provide good sensitivity, noise and timing characteristics, they still suffer from limitations owing to their large power consumption, high operation voltages and sensitivity to magnetic fields, as well as they are still bulky, fragile and expensive. New approaches to high-sensitivity imagers tend to use CCD cameras coupled with either MCP Image Intensifiers, I-CCDs, or Electron Multipliers, EM-CCDs (Dussault & Hoess, 2004), but they still have limited performances in extreme time-resolved measurements. A fully solid-state solution can improve design flexibility, cost, miniaturization, integration density, reliability and signal processing capabilities in photodetectors. In particular, Single- Photon Avalanche Diodes, SPADs, fabricated by conventional planar technology on silicon can be used as particle (Stapels et al., 2007) and photon (Ghioni et al., 2007) detectors with high intrinsic gain and speed. These SPAD are silicon Avalanche PhotoDiodes biased above breakdown. This operation regime, known as Geiger mode, gives excellent single-photon sensitivity thanks to the avalanche caused by impact ionization of the photogenerated carriers (Cova et al., 1996). The number of carriers generated as a result of the absorption of a single photon determines the optical gain of the device, which in the case of SPADs may be virtually infinite. The basic concepts concerning the behaviour of G-APDs and the physical processes taking place during their operation will be reviewed next, as well as the main performance parameters and noise sources.

Avalanche photodiodes operated in the Geiger mode offer a high intrinsic gain as well as an excellent timing accuracy. These qualities make the sensor specially suitable for those applications where detectors with high sensitivity and low timing uncertainty are required. Moreover, they are compatible with standard CMOS technologies, allowing sensor and front–end electronics integration within the pixel cell. However, the sensor suffers from high levels of intrinsic noise, which may lead to erroneous results and limit the range of detectable signals. They also increase the amount of data that has to be stored. In this work, we present a pixel based on a Geiger-mode avalanche photodiode operated in the gated mode to reduce the probability to detect noise counts interfering with photon arrival events. The readout circuit is based on a two grounds scheme to enable low reverse bias overvoltages and consequently lessen the dark count rate. Experimental characterization of the fabricated pixel with the HV–AMS 0.35 μm standard technology is also presented in this article.

In the last years the fabrication of SPAD cameras has become one of the main fields of interest in 3-D imaging and bioapplications. In this paper we present the comparison between two standard CMOS technologies to fabricate SPADs cameras. The two technologies used in the comparison are a high voltage 0.35μm technology from AMS and a high integration 130nm technology from STM. The advantage of using a standard CMOS technology among a dedicated is the possibility of integrating the control/reading electronics into the same die. Neither of the processes is optimized for optical applications, and no post-processing has been applied to improve the features. The technologies have been selected due to the different integration density, and different intrinsic process parameters with similar cost. Comparison has been done by fabricating several structures in both technologies which allow analyzing sensibility, noise, and time response. Experimental results show that the high voltage technology has a lower level of dark counts than the 130nm. Instead, the high integration technology has a shorter quenching time, 1.5ns, which reduces the afterpulsing events to a negligible level. In optical applications it is important to have a high integration of the camera reducing the pitch of the pixel, while noise effects can be corrected in post-processing. For low frequency events, such as high energetic particle tracking, the noise frequency has to be lower, but it is also required a high fill factor. Depending on the specific application this analysis allows to opt for the most suitable technology.

The present article describes the design of a new low-voltage radiation-tolerant band gap reference circuit. The proposed circuit has been designed for biasing analog modules in the slow control of the Data Handling Processor for reading DEPFET sensors in the Super KEK-B particle accelerator in Japan. It has been implemented in a 90nm standard CMOS technology. The BGR circuit provides a sub-1V voltage reference. It is possible to operate the circuit with 1 and 1.2V supplies. For that, a trimming net based on resistors was included. Tolerance to radiation is achieved by means of enclosed layout transistors and guard rings. The total area of the BGR is 181x110μm2. The power consumption is set at 18.70uA for the 1V supply case and at 55.18uA for the 1.2V supply case.

The high sensitivity and excellent timing accuracy of Geiger mode avalanche photodiodes makes them ideal sensors as pixel detectors for particle tracking in high energy physics experiments to be performed in future linear colliders. Nevertheless, it is well known that these sensors suffer from dark counts and afterpulsing noise, which induce false hits (indistinguishable from event detection) as well as an increase of the necessary area of the readout system. In this work, we present a comparison between APDs fabricated in a high voltage 0.35 µm and a high integration 0.13 µm commercially available CMOS technologies that has been performed to determine which of them best fits the particle collider requirements. In addition, a readout circuit that allows low noise operation is introduced. Experimental characterization of the proposed pixel is also presented in this work.

The influence of the calcination temperature and doping on the structural and electrical properties of SnO 2 nanopowders for gas sensors is investigated. The effectivity of grinding before and/or after calcination of the oxide will be discussed in terms of both structural modifications and electrical response of gas sensors.

It is presented a new method to control brushless micromotors which eliminates freewheeling currents. To test the method, a new driver has been designed and fabricated in a 0.35 µm standard CMOS process. It is shown in the paper how the driver is effectively reducing the freewheeling currents.

Particle detection can be done with many different sensors. In this case, the particle detector is based on avalanche photodiodes (APDs) integrated on standard CMOS technology. The integration of the sensors allows the possibility to integrate also the processing circuitry, reducing the volume of components, the complexity, and also the cost of the total device. The sensor is based on a double sensor detection to discriminate the inherent noise of APDs. An electrical model of the sensor, including noise modeling of dark counts and afterpulsing, based on fabricated component, has been developed to proof the suitability of the proposed detector circuit.

Microrobots were proposed more than 20 years ago but it has proven challenging to integrate a power system and actuators into some few mm3. There have been some attempts to create an autonomous mobile microrobot but any has been successful. Moreover, the proposed microrobots were simply mobile platforms incapable of sensing its environment and taking decisions. I-SWARM has been designed to be a real autonomous microrobot. It is powered by solar cells and provided with a locomotion unit for moving, an IR module for communicating and a contact tip for detecting near objects. Those modules are managed by an ASIC designed specifically for I-SWARM. All the electronics (power electronics, buffers, ADCs, DACs, control unit, analog transducers and an oscillator) have been embedded in the ASIC due to the limited area, 3 × 3 mm2. The ASIC is a complete System On Chip (SoC) that has several features not reported before in any circuit for microrobots: communicate and act cooperatively with other I-SWARM microrobots, detect near objects, measure distance to an object, light trailing and reprogramability. This paper gives some guidelines to design integrated circuits for microrobots.

This paper reports on the design and implementation of a low-voltage, low-power Wake-Up circuit consisting on a Power-on-Reset module and a clock generator. No external components are used neither for the Power-on- Reset nor for the clock generation. The clock generator module is temperature compensated by applying a current limiting technique. The Wake-Up circuit has been fabricated in a 130 nm ultra-low power technology of STMicroelectronics in an area of 40 μm times 40 μm.

A low power successive approximation analog-to-digital converter is presented operating at 1.2 V supply. The circuit has been designed in a 0.13 μm standard CMOS technology. The power consumption while converting is 13 μW, and in standby mode the power is reduced to 5.8 μW. The resolution is programmable between 1 to 8 bits. It can work from 500 Hz up to 50 kHz clock frequencies.

A digital controller for a 1 cm microrobot fabricated in a 0.35mum CMOS process is presented. The robot is provided with two piezoactuators based on stick-slip and non-sliding movement: a carrier platform and a rotor to position an arm provided with a nanomanipulation tool as an AFM tip. The control signals are generated by the controller chip using the Bresenham algorithm. It has been adapted to the robot movements improving the power consumption. Power reduction is of at least 30%

Transmission electron microscopy and optical absorption measurements on InxGa1−xAs tensile layers grown on InP (001), having a range of In composition varying between 42·0 and 51·6% and thicknesses of 0·1 and 0·4 μm, have been carried out. The characteristics of the growth mode depending on strain and layer thickness are presented, showing the degradation of the epilayer with increasing mismatch. In these tensile layers, a random three-dimensional mode of growth leading to a very rough surface morphology has been found in the most mismatched layers studied.MST/3330

A mixed-mode interface circuit for monolithically integrated gas sensor arrays has been developed. Circuitry includes the heater driver for the temperature control, interface electronics for inspection of up to four sensors array and interface logic for smart control. Because of its characteristics as robustness, small, size, low price and future capabilities with the adequate signal processing the system composed by the sensor and the application specific integrated circuit would be able to cover most of today markets considered for gas sensors.

The effort at the UB and CNM to study the feasibility of using standard CMOS technology Geiger avalanche photo-diodes (GAPDs) for pixel tracking detectors is reported. Generally APDs are used as photon detector devices. The possibility of using APDs in Geiger mode (that is reverse-biased above breakdown) for direct particle detection is the purpose of the ongoing R&D program, which tries to exploit GAPDs’ features suitable for particle detection.

The need to move forward in the knowledge of the subatomic world has stimulated the development of new particle colliders. However, the objectives of the next generation of colliders sets unprecedented challenges to the detector performance. The purpose of this contribution is to present a bidimensional array based on avalanche photodiodes operated in the Geiger mode to track high energy particles in future linear colliders. The bidimensional array can function in a gated mode to reduce the probability to detect noise counts interfering with real events. Low reverse overvoltages are used to lessen the dark count rate. Experimental results demonstrate that the prototype fabricated with a standard HV-CMOS process presents an increased efficiency and avoids sensor blindness by applying the proposed techniques.

This work presents low noise readout circuits for silicon pixel detectors based on Geiger mode avalanche photodiodes. Geiger mode avalanche photodiodes offer a high intrinsic gain as well as an excellent timing accuracy. In addition, they can be compatible with standard CMOS technologies. However, they suffer from a high intrinsic noise, which induces false counts indistinguishable from real events and represents an increase of the readout electronics area to store the false counts. We have developed new front-end electronic circuitry for Geiger mode avalanche photodiodes in a conventional 0.35 μm HV-CMOS technology based on a gated mode of operation that allows low noise operation. The performance of the pixel detector is triggered and synchronized with the particle beam thanks to the gated acquisition. The circuits allow low reverse bias overvoltage operation which also improves the noise figures. Experimental characterization of the fabricated front-end circuit is presented in this work.

The gated operation is proposed as an efficient method to reduce and uniformize noise figures in pixel detectors based on Geiger mode avalanche photodiodes. This idea has been proved by prototyping and characterizing a 3x3 array with the sensor and the front-end electronics monolithically integrated on a single CMOS die fabricated in a conventional CMOS technology.