Systèmes et microsystèmes multiphysiques

The researchers involved in the SMH team have advanced experience in the field of integrated systems for instrumentation. Such systems are composed of two specific subsets:

• a transducer that converts a physical quantity into an electrical signal,
• the instrumental chain that performs signal conditioning (amplification, processing, handling) of the transducer's electrical signal.

Most of the research topics in that area are strongly related to applications and are often based on industrial partnerships. Our main research activities focus on single-chip co-integration of transducers and their dedicated instrumental chains. In particular, ICube's SMH team has been developing advanced skills in the fields of mixed-signal, low-power, low-noise, ultra-fast systems design, IC design (mainly in CMOS, BiCMOS and high-voltage CMOS technologies) and complex signal processing.

Integrated magnetic sensors

Layout view of a Hall effect transducers-based 3D magnetic sensors integrated in CMOS technology

These activities concern the development of CMOS technology-compatible high-resolution magnetic sensors and mainly on Hall effect-based sensors that can measure one, two or three axis magnetic field components.

Silicon Hall effect sensors typically allow the measuring of both static and dynamic magnetic fields with resolution in the range of 10µT (for comparison purpose, the Earth magnetic field in Strasbourg is about 47 µT). This level of performance is usually achieved with Horizontal Hall Devices (HHD), i.e. transducers that are sensitive to the component that is perpendicular to the surface of the chip. 2D or 3D magnetic field sensors require the use of Vertical Hall Devices (VHD), i.e. sensitive to the component that is parallel to the surface of the chip, and are usually implemented in high-voltage compatible technologies to reach the same level of performance as HHDs. We have developed the first high-performance low-voltage CMOS technology compatible VHD (LV-VHD). Our most recent LV-VHD achieves best reported performance with about 50 µT resolution.

We have also been investigating a promising new device called the CHOPFET. The CHOPFET is a MAGFET-based (magnetic field-effect transistor) structure that allows the applying of the “spinning current” technique, so far applied to Hall devices only. This opens new perspective in terms of ultra-low power and ultra-high resolution fully CMOS compatible magnetic sensors.

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  Micrograph of perpendicular LV-VHDs

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  MRI 3D magnetic field gradient measurment

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  3D view of the CHOPFET structure

Related projects

The principal projects related to magnetic field sensors research activities are:

• development of a catheter magnetic navigation system for X-ray-based endovascular surgery
• XYZ-IRM project, "Development of a dedicated system for active minimally-invasive surgery tools tracking in IRM environment"
• industrial project in collaboration with SOCOMEC SA company, 2007-2011, "Development of a galvanomagnetic (contactless) current sensor for industrial applications"
• ANR TecSan project, SmartMRECG (Magnetic Resonance sequence synchronisation and ECG patient monitoring), 2008-2011, "Development of an ECG-Hall sensor for ECG signal measurement and processing in IRM environment"
• industrial project in collaboration with ABB company, "Rogowki coil-based current sensors with integrated conditioning electronics"

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  Active magnetic tracking system

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  Industrial current sensor

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  ECG signal correction with ECG-Hall system

Fast imagers

This activity aims at developing efficient devices dedicated to measure transient light phenomenons in the time domain, typically between 1 ms (digital CCD camera, intensified and shut) and 1 ps (streak camera), for scientific and industrial investigation purpose.

We have grown advanced experience in the field of instrumentation systems for optical metrology with both spatial and temporal resolution. In particular, we have been working on streak camera systems, which have extremely fast light phenomena measurement capabilities. Whatever the utilized technology (rotating mirror, vacuum tube or silicon), the "streak" approach has 100 to 1000 times better temporal resolution performance compared to the "framing" imagers, and without the constraints of the latter. Thus, these systems have incomparable direct light measurement performance and can also be adapted for measuring spatial or spectral variations.

The SMH team works on two approaches, i.e. two different technologies:

• the vacuum tube technology for both 2D (framing) and 1D (streak) camera design.
  • In framing mode, our ultrafast gated intensified camera achieves gating width of 200 ps FWHM. 2D images with 512x512 pixels spatial resolution are thus acquired at above 1 peta pixels/s sampling rate.
  • In streak mode, spatial resolution of our camera is reduced down to one single line of 1024 pixels with 2 ps per-pixel temporal resolution, leading to above 1 peta pixels/s total sampling rate.

• the fully integrated standard CMOS technology for solid-state 2D and 1D cameras.
  • In framing mode, our solid-state burst image sensors reach above 10 Mega frames/s frame rate, with 400x400 pixels spatial resolution, leading to above 1 tera pixels/s total sampling rate.
  • In streak mode, our sensors boast subnanosecond temporal resolution with up to 8 Gfps and 128 frames on-chip storage capacity.
  • Recurrent optical events can also be acquired at such temporal resolution, with extreme sensitivity, i.e. down to single photon counting, thanks to Single Photon Avalanche Diode (SPAD).

Our results lead to the development of a promising technology based on optical tomography of near-infrared diffusing environments, currently in use for medical applications. Time-resolved fluorescence is also an ideal utilization of our systems for applications such as FLIM imagers or high throughput screening of biomolecule thanks to micro fluidic chip.

Vacuum tube and integrated streak cameras

Related projects

The principal projects related to fast imagers research activities are:

• ANR JCJC SIROPOU project, 2008-2010, "system imageur pour l’observation des phenomènes optiques ultrarapides"
• ANR PICO² project, 2015-2019,in collaboration with IPCMS and the LBP, "les interactions biomoléculaires relevées par fluorescence PICOseconde dans les PICO litres”
• ANR FALCON project, 2014-2017, in collaboration with the CEA LETI, Dolphin Integration and the LPSC, "Caméra rapide 10 millions d’images par seconde par assemblage nanotechnologique"
• Alsace Region/FUI SPIRIT project, 2009-2011, in collaboration with Telmat SA, Photonis (pays-bas), Montena (suisse), "Réalisation d'un système d'imagerie médicale constituant un outil de diagnostic"
• SATT "Maturation" ISC project, 2016-2018, in collaboration with Optronis GmbH, "Caméra à balayage de fente à résolution sub-nanoseconde en technologie CMOS"
• scientific collaboration project MAITODIC, in collaboration with the Institut de Saint Louis (ISL), 2014 – 2017, "Développement d'un démonstrateur de capteur d'imagerie 3D CMOS par temps de vol photonique sur la base d'un concept ISL"

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  Vacuum tube streak camera

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  CMOS streak camera

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  Subnanosecond temporal resolution

Chemical sensors

Test bench for chemical sensor system combining O-FET devices to a dedicated high-voltage CMOS conditioning IC

Integrated chemical sensors find their applications in several fields such as medicine, healthcare, security or industry, where there is a growing interest for more efficient, more compact, faster and cheaper devices.

Therefore, since 2010, we have been developing new activities around chemical sensors. More specifically, we aim at interfacing chemical sensors made out of various materials (CNTFET, O-FET, etc.) with their dedicated integrated conditioning electronics. For technological reasons, new electronic devices for chemical phenomenon measurement often require high-voltages (up to several tens of volts) to be properly operated. Therefore, we have been investigating high-voltage CMOS technology-compliant instrumental chains. In particular, we have proposed new high-efficiency DC-DC converters topologies and a dimensioning tool for DC-DC converters conception and optimization. From low-voltage standard IC supply voltage (1.8V, 3.3, 5V), our DC-DC converters can supply power for high-voltage modules (typically operated at 40 to 50 V) on resistive loads (up to several tens of µA).

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  O-FET molecule

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  O-FET structure

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  DC-DC converter, LCP topology

Related projects

The projects related to the chemical sensors activities are:

• ANR CAPTEX, 2010-2013, "Modeling of CNTFET-based explosive gas sensors and development of their dedicated fully integrated conditioning electronics"
• API CORALIE, 2015-2016, "Study and fabrication of organic transistors O-FET and their dedicated fully integrated conditioning electronics, functionalizing for biological or medical applications"

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  O-FET Ids=f(Vgate) characteristic curve

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  High-voltage CMOS IC for chemical sensor

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  CNTFET-based sensor test board