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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.

Proceedings of the 29th International Workshop on Vertex Detectors (VERTEX2020), Tsukuba, Japan (Online); Journal of the Physical Society of Japan 34, 010002 (2021). doi:10.7566/JPSCP.34.010002, The Belle II experiment at the super KEK B factory (SuperKEKB) started its physics operation with the full detector setup in March 2019, and it aims at collecting 50 ab$^{���1}$ of $e^+e^���$ collision data. The vertex detector (VXD) of Belle II contains a 4-layer silicon vertex detector (SVD) using double sided silicon strips and an inner 2-layer pixel detector (PXD) that is based on the depleted P-channel Field Effect Transistor (DEPFET) technology. The signal generation and amplification are combined in pixels with a minimum pitch of 55 �� 50 ��m$^2$. The sensors are thinned down to 75 ��m, and each module has interconnects and ASICs integrated on the sensor with silicon frames for mechanical support. This approach led to a material budget of around 0.21% X$_0$ per layer including the cooling structure in the acceptance region. The PXD has an integration time of around 20 ��s, a signal-to-noise ratio of around 50 and a detecting efficiency of better than 99%. Its two layers are arranged at the radii of 14 and 22 mm around the interaction point, and an impact parameter resolution of better than 15 ��m has been achieved. Due to its close proximity to the beam line and its sensitivity to few-keV photons, the PXD also plays an important role in background studies., Published by The Physical Society of Japan, Tokyo

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.

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

Belle-II DEPFET and PXD Collaboration: et al., A DEpleted P-channel Field Effect Transistor (DEPFET) based pixel detector was developed for the Belle II VerteX Detector (VXD). It is designed to achieve a good impact parameter resolution better than 15𝜇m at the very high luminosity conditions of this experiment. In the first half of 2018 four final production modules have been deployed in the commissioning run of the detector and their performance is discussed., This work is supported by MEXT, WPI, and JSPS (Japan); MSMT, GAUK 404316, MSCA-RISE project JENNIFER (EU grant n. 644294) (Czech Republic); Federal Ministry of Education and Research (BMBF, Germany) and MINECO grant FPA2015-71292-C2-1-P (Spain).

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.

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.

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.

The extraordinary sensitivity of single-photon avalanche diodes (SPADs) makes these devices the ideal option for vision systems aimed at low-light applications. Nevertheless, there exist large dark count rate and photon detection probability non-uniformities, which reduce the dynamic range of the detector. As a result, the capability to create image contrast is severely damaged or even lost. This paper presents the implementation of a correction algorithm to compensate for the mentioned non-uniformities and thus extend the contrast of the generated images. To demonstrate its efficiency, the proposed technique is applied to real images obtained with a fabricated SPAD image sensor. An increase of more than 3 b of contrast is obtained.

This work presents the development of a Geiger-mode Avalanche PhotoDiode pixel detector in standard CMOS technologies aimed at the vertex and tracker regions of future linear colliders, i.e. the International Linear Collider and the Compact LInear Collider. In spite of all the advantages that characterize this technology, GAPD detectors suffer from noise pulses that cannot be distinguished from real events and low fill-factors that reduce the detection efficiency. To comply with the specifications imposed by the next generation of particle colliders, solutions to minimize the intrinsic noise pulses and increase the fill-factor have been thoroughly investigated.

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.

The silicon photomultiplier (SiPM) is a novel detector technology that has undergone a fast development in the last few years owing to its notable advantages, which comprise single-photon resolution and ultra-fast response time. However, the typical high dark count rates of the sensor may prevent the detection of low-intensity radiation fluxes. In this article, the time-gated operation with short active periods in the nanosecond range is proposed as a solution to reduce the number of cells fired due to noise in those application fields that function under a trigger command, such as gated fluorescence lifetime imaging microscopy.

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.

An optical imager for triggered applications is presented. The detector consists of a 10 × 43 array of single-photon avalanche pixels and exhibits an unusual fill-factor of 67%. It has been fabricated in a conventional 0.35 μm HV-CMOS process. The array presents an average dark count rate of 67 kHz at a reverse bias overvoltage of 1 V. Due to the large sensor area of 20 μm × 100 μm, the array is operated in a time-gated mode to reduce the probability of detecting the sensor noise down to 10 −4 noise counts per frame with an active period of 4 ns. The crosstalk can be minimized to negligible levels also by means of the time-gated operation. A number of experiments have been conducted on the detector to show that the proposed technique is advantageous in improving the imager signal-to-noise ratio, dynamic range, contrast and spatial resolution.

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 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.

The CERN Beam Instrumentation group has been working during the last years on the beam wire scanners upgrade to cope up with the increasing requirements of CERN experiments. These devices are used to measure the beam profile by crossing a thin wire through a circulating beam, the resulting secondary particles produced from beam/wire interaction are detected and correlated with the wire position to reconstruct the beam profile. The upgraded secondary particles acquisition electronics will use polycrystalline chemical vapour deposition (pCVD) diamond detectors for particle shower measurements, with low noise acquisitions performed on the tunnel, near the detector. The digital data is transmitted to the surface through an optical link with the GBT protocol. Two integrator ASICs (ICECAL and QIE10) are being characterized and compared for detector readout with the complete acquisition chain prototype. This contribution presents the project status, the QIE10 front-end performance and the first measurements with the complete acquisition system prototype. In addition, diamond detector signals from particle showers generated by an operational beam wire scanner are analysed and compared with an operational system.

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%.

Recent progresses in miniaturization of sensors and actuators have yielded to the first attempt to create an mm3 -sized autonomous robot with sensing capabilities called I-SWARM. The robot is conceived to interact with other I-SWARM robots in order to create a robotic swarm. It is provided with a locomotion unit, an infrared communication system, a contact sensor, solar cells for powering, and a system on chip (SoC) that acts as the brain of the robot. All these components are mounted over a flexible printed circuit board, being I-SWARM a real system in package (SiP). The SoC communicates with other I-SWARMs, sense its environment, processes data and takes decisions, as for example moving, with less than 1.5 mW. Different electronic circuits (power electronics, buffers, ADCs, DACs, control units, analog transducers, and even an oscillator) have been embedded in the SoC due to the limited area, less than 3 × 3 mm2. The SoC is reprogrammable optically in order to change the behavior of the microrobot.

In this paper we discuss the noise analysis of time variant shapers in the frequency domain, based on well established concepts of the theory of time varying circuits. A frequency domain extension of the techniques typically adopted for noise analysis in detector instrumentation is proposed and applied to a classic time variant shaper: the gated integrator. In some cases, this frequency domain method makes easier the study of systems in which one of the blocks or noise sources is better described in the frequency domain. In that sense, a practical case involving a gated integrator and a Correlated Double Sampler (CDS) time variant shaper is presented.

Advances in single photon avalanche detector (SPAD) arrays propose improving the fill factor by confining several SPADs in the same well, with a main issue related to crosstalk. In applications that measure at fixed times, the pixels can be inhibited before the arrival of the crosstalk charge. This letter reports the crosstalk characterization in an array of SPADs, where the sensors share the same n-well (fill factor 67%), and fabricated in a conventional CMOS technology. The reduction of the gating time completely eliminates the crosstalk, as predicted by the theory and TCAD simulations.

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.

The objective of this paper is to present the design and validation of a cantilever-based contact sensing system for a micro-robot. Key elements of the fabrication process of the sensor and the ele ...

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 increasing requirements of CERN experiments make essential the upgrade of beam instrumentation in general, and high accuracy beam profile monitors in particular. The CERN Beam Instrumentation Group has been working during the last years on the Wire Scan- ners upgrade. These systems cross a thin wire through a circulating beam, the resulting secondary particles produced from beam/wire interaction are detected to reconstruct the beam profile. For the new secondary shower acquisition system, it is necessary to perform very low noise measurements with high dynamic range coverage. The aim is to design a system without tuneable parameters and compatible for any beam wire scanner location at the CERN complex. Polycrystalline chemical vapour deposition diamond detectors (pCVD) are proposed as new detectors for this application because of their radiation hardness, fast response and linearity over a high dynamic range. For the detector readout, the acquisition electronics must be designed to exploit the detector capabilities and perform bunch by bunch measurements at 40MHz. This paper describes the design challenges of such a system, analysing different acquisition possibilities from the signal integrity point of view. The proposed system architecture is shown in detail and the development status presented.

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.

The advances of the semiconductor industry enable microelectromechanical systems sensors, signal conditioning logic and network access to be integrated into a smart sensor node. In this framework, a mixed-mode interface circuit for monolithically integrated gas sensor arrays was developed with high-level design techniques. This interface system includes analog electronics for inspection of up to four sensor arrays and digital logic for smart control and data communication. Although different design methodologies were used in the conception of the complete circuit, high-level synthesis tools and methodologies were crucial in speeding up the whole design cycle, enhancing reusability for future applications and producing a flexible and robust component.

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 silicon photomultiplier (SiPM) is a novel detector technology that has undergone a fast development in the last few years, owing to its single-photon resolution and ultra-fast response time. However, the typical high dark count rates of the sensor may prevent the detection of low intensity radiation fluxes. In this article, the time-gated operation with short active periods in the nanosecond range is proposed as a solution to reduce the number of cells fired due to noise and thus increase the dynamic range. The technique is aimed at application fields that function under a trigger command, such as gated fluorescence lifetime imaging microscopy.

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.

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.

a b s t r a c t A bidimensional array based on single­photon avalanche diodes for triggered imaging systems is pre­ sented. The diodes are operated in the gated mode of acquisition to reduce the probability to detect noise counts interfering with photon arrival events. In addition, low reverse bias overvoltages are used to lessen the dark count rate. Experimental results demonstrate that the prototype fabricated with a stan­ dard HV­CMOS process gets rid of afterpulses and offers a reduced dark count probability by applying the proposed modes of operation. The detector exhibits a dynamic range of 15 bits with short gated ‘on’ periods of 10 ns and a reverse bias overvoltage of 1.0 V.

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.

Miniaturization of sensors and actuators up to the point of active features in endoscopic capsules, such as locomotion or surgery, is a challenge. VECTOR endoscopic capsule has been designed to be the first endoscopic capsule with active locomotion. It is equipped with mini-legs driven by Brushless DC (BLDC) micro motors. In addition it can be also equipped with some other sensors and actuators, like a liquid lens, that permits to enable advanced functions. Those modules are managed by an ASIC specifically designed for the VECTOR capsule. The ASIC is a complete System-On-Chip (SoC) and integrates all the electronics needed to enable the legged locomotion and the sensing and actuating functions of the capsule in an unique chip. The SoC also enables other functions for endoscopic capsules such as drug delivery and a biopsy system. The size of the SoC is 5.1 mm × 5.2 mm in a 0.35 um high voltage CMOS technology.

Commercial endoscopic capsules are passive. Nevertheless, active capabilities such as active locomotion, drug delivery or biopsy, among others, can now be offered with the aid of robotics. New robotic functions require additional electronics for control purposes, as well as for the sensors and actuators. To avoid increasing the capsule size as a consequence, it is useful to incorporate all the electronics into the minimum number of elements, preferably in a single ASIC. This paper describes the ASIC included in a robotised capsule with the abovementioned active functions. The ASIC is a system-on-chip (SoC) integrating all the electronics needed to control the other electronic elements in the capsule. It also enables the movement of two BLDC motors, illuminates the exploration region and focuses a liquid lens used to achieve advanced vision capabilities. Details of the complete system integration are also given.

Single-photon avalanche diodes (SPADs) are nowadays the most consolidate solid-state alternative to photomultiplier tubes and time-correlated single-photon counting. Optical benches are used for the characterization of the noise figures of these detectors, including dark count, afterpulsing effects and cross-talk. With accurate optical setups it is possible to obtain resolutions down to 5 microns, but with today's technologies, this spot size can cover more than one single pixel. Moreover, on other common and envisaged applications like particle detection in Nuclear and High Energy Physics or as silicon photomultipliers for Cerenkov telescopes, this does not allow to observe what happens when a charge is generated between consecutive pixels. This work presents the innovative characterization of single-photon detectors with the aid of the electron beam generated in a dual beam FIB/SEM apparatus. A simple setup allows a very good control of the dose and the spot down to 5 nm at 30 keV, The characterization has been proven in photodetectors fabricated in a standard CMOS technology. The results have been validated by comparison with those obtained by optical setups, with simulation with PENELOPE (Penetration and Energy Loss of Positrons and Electrons) and by technology simulations with ISE-tCAD.

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.

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.

The paper reports the electronics used in a new developed wireless endoscopic capsule provided with novel focus and locomotion features. The locomotion is enabled by using legs driven by 2 brushless DC (BLDC) micromotors. The focusing system is enabled by using a liquid lens with a variable focal. These functions are managed by an ASIC that has been developed to provide the specific innovative functions. The size of the ASIC is 3.0 mm × 2.7 mm in a 0.35 um high voltage CMOS technology. The ASIC is described in detail, as well as the performances when it is used with the final devices used in the capsule.