Front-end Multiplexing - applied to SQUID multiplexing : Athena X-IFU and QUBIC experiments

As we have seen for digital camera market and a sensor resolution increasing to "megapixels", all the scientific and high-tech imagers (whatever the wave length - from radio to X-ray range) tends also to always increases the pixels number. So the constraints on front-end signals transmission increase too. An almost unavoidable solution to simplify integration of large arrays of pixels is front-end multiplexing. Moreover, "simple" and "efficient" techniques allow integration of read-out multiplexers in the focal plane itself. For instance, CCD (Charge Coupled Device) technology has boost number of pixels in digital camera. Indeed, this is exactly a planar technology which integrates both the sensors and a front-end multiplexed readout. In this context, front-end multiplexing techniques will be discussed for a better understanding of their advantages and their limits. Finally, the cases of astronomical instruments in the millimeter and in the X-ray ranges using SQUID (Superconducting QUantum Interference Device) will be described

SQUIDs et Méthodes de Multiplexage

École thématiqueLe SQUID (Superconducting QUantum Interference Device) est un élément essentiel du développement du multiplexage cryogénique. Il fonctionne à température cryogénique, bénéficie d'une grande bande passante (~MHz) et d'un très faible bruit (~pA/√Hz). Dans un premier temps, les deux principes analogiques de multiplexage temporel et fréquentiel seront présentés. Dans un deuxième temps, on parlera de l'utilisation du SQUID qui permet de réaliser un multiplexage temporel ou fréquentiel à l'intérieur d'un cryosta

Commercially Available Capacitors at Cryogenic Temperatures

Commercially available capacitors are not specified for operation at 77 K or 4 K, and some devices showed a dramatic decrease of capacitance at cryogenic temperature. Furthermore, for voltage biasing of cryogenic low impedance sensors it is very important to know parasitic resistance. In this case, the parasitic Equivalent Series Resistance (ESR) of the capacitor used for the AC-biasing is a bottleneck of the voltage biasing. Involved in TES development and SQUID multiplexing, we have characterized the capacitance and the ESR values of some commercially available capacitors at 77 K and 4 K

Introduction au Langage C

DEACours/TPs/examen: Introduction au langage C et C+

Targeting microRNA to improve diagnostic and therapeutic approaches for malignant mesothelioma

Malignant mesothelioma is an aggressive and often fatal cancer associated with asbestos exposure. The disease originates in the mesothelial lining of the serosal cavities, most commonly affecting the pleura. Survival rates are low as diagnosis often occurs at an advanced stage and current treatments are limited. Identifying new diagnostic and therapeutic targets for mesothelioma remains a priority, particularly for the new wave of victims exposed to asbestos through do-it-yourself renovations and in countries where asbestos is still mined and used. Recent advances have demonstrated a biological role for the small but powerful gene regulators microRNA (miRNA) in mesothelioma. A number of potential therapeutic targets have been identified. MiRNA have also become popular as potential biomarkers for mesothelioma due to their stable expression in bodily fluid and tissues. In this review, we highlight the current challenges associated with the diagnosis and treatment of mesothelioma and discuss how targeting miRNA may improve diagnostic, prognostic and therapeutic approaches

Single-Photon Avalanche Diodes (SPAD) in CMOS 0.35 µm technology

International audienceSome decades ago single photon detection used to be the terrain of photomultiplier tube (PMT), thanks to its characteristics of sensitivity and speed. However, PMT has several disadvantages such as low quantum efficiency, overall dimensions, and cost, making them unsuitable for compact design of integrated systems. So, the past decade has seen a dramatic increase in interest in new integrated single-photon detectors called Single-Photon Avalanche Diodes (SPAD) or Geiger-mode APD. SPAD are working in avalanche mode above the breakdown level. When an incident photon is captured, a very fast avalanche is triggered, generating an easily detectable current pulse.This paper discusses SPAD detectors fabricated in a standard CMOS technology featuring both single-photon sensitivity, and excellent timing resolution, while guaranteeing a high integration. In this work, we investigate the design of SPAD detectors using the AMS 0.35 µm CMOS Opto technology. Indeed, such standard CMOS technology allows producing large surface (few mm2) of single photon sensitive detectors. Moreover, SPAD in CMOS technologies could be associated to electronic readout such as active quenching, digital to analog converter, memories and any specific processing required to build efficient calorimeters1 (Silicon PhotoMultiplier – SiPM) or high resolution imagers (SPAD imager). The present work investigates SPAD geometry. MOS transistor has been used instead of resistor to adjust the quenching resistance and find optimum value. From this first set of results, a detailed study of the dark count rate (DCR) has been conducted. Our results show a dark count rate increase with the size of the photodiodes and the temperature (at T=22.5 °C, the DCR of a 10 µm-photodiode is 2020 count s−1 while it is 270 count s−1 at T=−40 °C for a overvoltage of 800 mV). A small pixel size is desirable, because the DCR per unit area decreases with the pixel size. We also found that the adjustment of overvoltage is very sensitive and depends on the temperature. The temperature will be adjusted for the subsequent experiments

Nondissipative Addressing for Time-Division SQUID Multiplexing

International audienceRecent and future astronomical instruments are based on a focal plane mapped by a large array of superconducting bolometers. Cryogenic analog multiplexing readout techniques, based on superconducting quantum interference devices (SQUIDs), are currently developed to achieve the readout of large arrays of this kind of low noise background-limited detectors. To effectively reduce the number of cryogenic wires (particularly, SQUID biasing), line/column addressing is currently used in time-division multiplexing, i.e., same biasing is applied to a few SQUIDs (on a line) of different columns. This technique should dramatically increase power consumption if parallel biasing is applied via resistors to isolate each column; the power budget is particularly limited on this kind of front-end cryogenic readout. A design with one transformer per SQUID is also used to read out SQUID biased in series with no excess of consumption and crosstalk. We propose here a new biasing technique using simple surface-mounted capacitors, which is easier to implement. These capacitors are used to parallel bias SQUIDs without additional Joule effect while minimizing crosstalk. However, capacitors do not allow dc biasing and need a current mean value equal to zero to avoid biasing source saturation. We have then tested square current biasing through capacitors on a commercial SQUID. This measurement shows that capacitors are able to proper bias SQUID and then to perform a nondissipative addressing for time-division SQUID multiplexing

Dark Count rate measurement in Geiger mode and simulation of a photodiode array, with CMOS 0.35 technology and transistor quenching.

International audienceSome decades ago single photon detection used to be the terrain of photomultiplier tube (PMT), thanks to its characteristics of sensitivity and speed. However, PMT has several disadvantages such as low quantum efficiency, overall dimensions, and cost, making them unsuitable for compact design of integrated systems. So, the past decade has seen a dramatic increase in interest in new integrated single-photon detectors called Single-Photon Avalanche Diodes (SPAD) or Geiger-mode APD. SPAD detectors fabricated in a standard CMOS technology feature both single-photon sensitivity, and excellent timing resolution, while guarantying a high integration. SPAD are working in avalanche mode above the breakdown level. When an incident photon is captured, a very fast avalanche is triggered, generating an easily detectable current pulse. In this work, we investigate the design of SPAD detectors using the Austriamicrosystems 0.35 μm CMOS Opto technology. A series of different SPADs has been fabricated and benchmarked in order to evaluate a future integration into a SPAD- based image sensor. The main characteristics of each SPAD operating in Geiger-mode are reported: current voltage, breakdown voltage as a function of temperature. From this first set of results, a detailed study of the Dark Count Rate (DCR) has been conducted. Our results show a dark count rate increase with the size of the photodiodes and the temperature (at T=22.5°C, the DCR of a 10μm-photodiode is 2020 count.s-1 while it is 270 count.s-1 at T=- 40°C for a overvoltage of 800mV). We found that the adjustment of overvoltage is very sensitive and depends on the temperature. The temperature will be adjusted for the subsequent experiments. A mathematical model is presented for reproduce the DCR of a single photodiode. We simulated the noise (DCR) of array of 32x32 photo-detectors. Our results show, of course an increase of DCR of 1024, but especially, the probability of having two pulses simultaneously is 0 (without light). By studying these probabilities of occurrence of the pulses, we think we can reduce the DCR of 50% with a statistical method and reduce the crosstalk of 90%. This study is realized in order to prepare the first digital matrices sensor in Geiger mode

The role of IL-6 in skin fibrosis and cutaneous wound healing

The timely resolution of wound healing is critical for restoring the skin as a protective barrier. The switch from a proinflammatory to a reparative microenvironment must be tightly regulated. Interleukin (IL)-6 is a key modulator of the inflammatory and reparative process: it is involved in the differentiation, activation, and proliferation of leukocytes, endothelial cells, keratinocytes, and fibroblasts. This review examines the role of IL-6 in the healing of cutaneous wounds, and how dysregulation of IL-6 signaling can lead to either fibrosis or a failure to heal. The role of an IL-6/TGF-β feedback loop is discussed in the context of fibrogenesis, while IL-6 expression and responses in advanced age, diabetes, and obesity is outlined regarding the development of chronic wounds. Current research on therapies that modulate IL-6 is explored. Here, we consider IL-6′s diverse impact on cutaneous wound healing

The contribution of animal models to understanding the role of the immune system in human idiopathic pulmonary fibrosis

Pulmonary fibrosis occurs in a heterogeneous group of lung disorders and is characterised by an excessive deposition of extracellular matrix proteins within the pulmonary interstitium, leading to impaired gas transfer and a loss of lung function. In the past 10 years, there has been a dramatic increase in our understanding of the immune system and how it contributes to fibrogenic processes within the lung. This review will compare some of the models used to investigate the pathogenesis and treatment of pulmonary fibrosis, in particular those used to study immune cell pathogenicity in idiopathic pulmonary fibrosis, highlighting their advantages and disadvantages in dissecting human disease