Papers by Marco Sampietro
Copyright and moral rights for the publications made accessible in the public portal are retained... more Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
The paper will describe a new photodetector based on a metal-organic semiconductor material sensi... more The paper will describe a new photodetector based on a metal-organic semiconductor material sensitive to the near IR region of the electromagnetic spectrum. The detector has a planar metal-semiconductor-metal structure with the active material deposited from liquid phase over a quartz substrate. Together with the fabrication process and the time response to light pulses, emphasis will be given to the intrinsic wavelength selectivity of the semiconductor material, of about 100nm around its peak sensitivity. The ease of deposition may enable to directly develop optical devices on passive optical component or on electronic substrates.
Nuclear Instruments and Methods in Physics Research, Aug 1, 1996
We report on the performance of a doublet of 3" cylindrical silicon drift detectors installed as ... more We report on the performance of a doublet of 3" cylindrical silicon drift detectors installed as an upgrade of the CERES/NA45 electron pair spectrometer for the Pb-beam at the CERN SPS. The silicon detectors provide external particle tracking and background rejection of conversions and close Dalitz pairs. Results on vertex reconstruction and rejection from a Pb test-run in 1994 are presented.
Small, Dec 28, 2015
Methods for the manipulation of single magnetic particles have become of particular interest for ... more Methods for the manipulation of single magnetic particles have become of particular interest for in-vitro biological studies. Most of them require an external microscope to provide the operator with the feedback for controlling the particle motion, thus preventing their use in high throughput experiments. In this paper, a simple and compact system with integrated electrical feedback is presented, implementing in the very same device both the manipulation and the detection of single particles transit. The proposed platform is based on zig-zag shaped magnetic nanostructures, where transverse magnetic domain walls are pinned at the corners and attract magnetic particles in suspension. By applying suitable external magnetic fields, domain walls move to the nearest corner, thus causing the step by step displacement of the particles along the nanostructure. The very same structure is employed also for detecting the bead transit. Indeed, the presence of the magnetic particle over the domain wall affects the depinning field required for its displacement. This characteristic field can be monitored Received: ((will be filled in by the editorial staff)) Revised: ((will be filled in by the editorial staff))
arXiv (Cornell University), May 14, 2019
In Broadband Stimulated Raman Spectroscopy, the intrinsic limit given by the laser shot noise is ... more In Broadband Stimulated Raman Spectroscopy, the intrinsic limit given by the laser shot noise is seldom reached due to the electronic noise of the front-end amplifier and the intensity fluctuations of the laser source. In this paper we present a low-noise multi-channel acquisition system, with an integration-oriented design, able to compensate the common-mode fluctuations of the laser output power with the pseudo-differential structure and reach a sensitivity better than 10 ppm thanks to the lock-in technique.
Automatic control of the silicon microring OSR and multiplexer in DML-based WDM transmitter for 40G TWDM-PON OLT
We present a control system for wavelength stabilization of silicon MRR used to improve ER in a f... more We present a control system for wavelength stabilization of silicon MRR used to improve ER in a four-channel DML-based transmitter. The ER enhancement is achieved with automatic control and the sensitivity of the system is better than -28 dBm at 10-3 BER after 40-km transmission.
4×10 Gbit/s L-band WDM transmitter with automatic control of silicon photonic channel multiplexer and carver
We present an L-band WDM transmitter exploiting a feedback-controlled Si photonic circuit for cha... more We present an L-band WDM transmitter exploiting a feedback-controlled Si photonic circuit for channel multiplexing and extinction ratio enhancement of four DML sources. 4×10 Gbit/s transmission along a 50-km SMF is demonstrated.
<title>Progress with PN-CCDs for the XMM satellite mission</title>
Proceedings of SPIE, Oct 1, 1991
ABSTRACT
Conduction and degradation analysis of organic LEDs by current noise monitoring
Proceedings of SPIE, Feb 27, 2002
... Phys. 80, (1996), 6002 6. VNSavvateev, AVYakimov, D.Davidov, R.Pogreb, MRNeuman, Y.Avny, Appl... more ... Phys. 80, (1996), 6002 6. VNSavvateev, AVYakimov, D.Davidov, R.Pogreb, MRNeuman, Y.Avny, Appl.Phys.Lett. 71 (1997) 3344 7. ST Lee, ZQ Gao, LS Hung, Appl. Phys. Lett. 75, (1999), 1404 8. M. Probst, R. Haight, Appl. Phys. Lett. ...
Proceedings of SPIE, May 4, 2011
Lab-on-a-chip systems have been attracting a growing attention for the perspective of miniaturiza... more Lab-on-a-chip systems have been attracting a growing attention for the perspective of miniaturization and portability of bio-chemical assays. Here we present a the design and characterization of a miniaturized, USB-powered, self-contained, 2-channel instrument for impedance sensing, suitable for label-free tracking and real-time detection of cells flowing in microfluidic channels. This original circuit features a signal generator based on a direct digital synthesizer, a transimpedance amplifier, an integrated square-wave lock-in coupled to a ΣΔ ADC converter, and a digital processing platform. Real-time automatic peak detection on two channels is implemented in a FPGA. System functionality has been tested with an electronic resistance modulator to simulate 1% impedance variation produced by cells, reaching a time resolution of 50μs (enabling a count rate of 2000 events/s) with an applied voltage as low as 200mV. Biological experiments have been carried out counting yeast cells. Statistical analysis of events is in agreement with the expected amplitude and time distributions. 2-channel yeast counting has been performed with concomitant dielectrophoretic cell separation, showing that this novel and ultra compact sensing system, thanks to the selectivity of the lock-in detector, is compatible with other AC electrical fields applied to the device.
Sensors and Actuators B-chemical, Apr 1, 2017
In recent years, the development of portable platforms for performing fast and point-of-care anal... more In recent years, the development of portable platforms for performing fast and point-of-care analyses has drawn considerable attention for their wide variety of applications in life science. In this framework, tools combining magnetoresistive biosensors with magnetic markers have been widely studied in order to detect concentrations of specific molecules, demonstrating high sensitivity and ease of integration with conventional electronics. In this work, first, we develop a protocol for efficient hybridization of natural DNA; then, we show the detection of hybridization events involving natural DNA, namely genomic DNA extracted from the pathogenic bacterium Listeria monocytogenes, via a compact magnetic tunneling junction (MTJ)-based biosensing apparatus. The platform comprises dedicated portable electronics and microfluidic setups, enabling point-of-care biological assays. A sensitivity below the nM range is demonstrated. This work constitutes a step forward towards the development of portable lab-on-chip platforms, for the multiplexed detection of pathogenic health threats in food and food processing environment.
IEEE Transactions on Biomedical Circuits and Systems, Dec 1, 2017
A dual-channel credit-card-sized impedance cell counter featuring a throughput of 2000 cell/s and... more A dual-channel credit-card-sized impedance cell counter featuring a throughput of 2000 cell/s and detection of single yeast cells (5 μm) with a signal-to-noise ratio of 20 dB is presented. Its compactness is achieved by a CMOS ASIC combining a lock-in impedance demodulator with an oversampling 20-bit ADC and real-time peak detection embedded in field-programmable gate ar-ray. The module is coupled to a dielectrophoretic cell-sorting mi-crofluidic device, offering compact and label-free electrical readout that replaces the need for a fluorescence microscope and, thus, is suitable for pointof-care diagnostics. The independent role of each dimension of the planar sensing microelectrodes is demonstrated, with simulations and experiments, along with its relevant effect on the spectrum of thin channels, deriving useful design guidelines.
Journal of Lightwave Technology, Nov 15, 2021
The noise power spectral density of a detector is essential for determining the frequency of oper... more The noise power spectral density of a detector is essential for determining the frequency of operation and readout architecture that yields an optimal signal-to-noise ratio. In this work, we characterize a waveguide-integrated PbTe mid-infrared detector and report on its noise spectrum, highlighting the presence of a current-dependent 1/f term dominating at low frequency and/or high bias over the Johnson component typical of a photoconductor. This behaviour, together with the substantially flat frequency response in the range between 1 kHz to 1 MHz, guide towards a lock-in readout strategy, that allows one to operate in the region of minimum noise without penalties in the detection performance. Practical guidelines to optimize the readout resolution are provided and the limit of detection of a gas sensing system exploiting PbTe photoconductors is derived, as an example of how a careful co-design of sensors and electronics can dramatically improve the detection performance.
A power efficient, battery powered optogenetic headstage for doing in-vivo experiments with freel... more A power efficient, battery powered optogenetic headstage for doing in-vivo experiments with freely moving genetically modified animals is presented. The proposed system is designed with commercial off-the-shelf components, and is based on a Bluetooth Low Energy (BLE) System-on-Chip (SoC) with an integrated antenna and a programmable ARM Cortex-M3 microprocessor core able to control the circuit. The optical signal is generated using a compact laser diode (LD) suitable for a wearable headstage. LD produces light in a highly concentrated way considerably improving the LD-optical fiber coupling efficiency. The proposed optogenetic system is shown to provide 120 mW/mm 2 at the fiber tip with a current consumption of 60mA, considerably lower than LED-based systems. The system is remotely controlled by a smartphone app where the user can define optical stimulations patterns settings (optical power, frequency, duty cycle, etc.). It is also powerful enough to be ready to house additional optogenetics functionalities, like electrochemical sensing of the cell response, without significant modifications, thus being the basis of an integrated optogenetic platform.
The intrinsic sensitivity limit of Stimulated Raman Spectroscopy (SRS) is given by the shot noise... more The intrinsic sensitivity limit of Stimulated Raman Spectroscopy (SRS) is given by the shot noise of the optical stimulation. However, it is seldom reached due to the electronic noise of the front-end amplifier and the intensity fluctuations of the laser source. Here, we present a low-noise differential amplifier able to compensate the common-mode fluctuations given by the laser and to reach a sensitivity better than 10 ppm thanks to the lock-in technique.
arXiv (Cornell University), Dec 11, 2007
APL Photonics
Spontaneous Raman microscopy reveals the chemical composition of a sample in a label-free and non... more Spontaneous Raman microscopy reveals the chemical composition of a sample in a label-free and non-invasive fashion by directly measuring the vibrational spectra of molecules. However, its extremely low cross section prevents its application to fast imaging. Stimulated Raman scattering (SRS) amplifies the signal by several orders of magnitude thanks to the coherent nature of the nonlinear process, thus unlocking high-speed microscopy applications that provide analytical information to elucidate biochemical mechanisms with subcellular resolution. Nevertheless, in its standard implementation, narrowband SRS provides images at only one frequency at a time, which is not sufficient to distinguish constituents with overlapping Raman bands. Here, we report a broadband SRS microscope equipped with a home-built multichannel lock-in amplifier simultaneously measuring the SRS signal at 32 frequencies with integration time down to 44 µs, allowing for detailed, high spatial resolution mapping of ...
Advanced Science, 2021
Malaria remains the most important mosquito‐borne infectious disease worldwide, with 229 million ... more Malaria remains the most important mosquito‐borne infectious disease worldwide, with 229 million new cases and 409.000 deaths in 2019. The infection is caused by a protozoan parasite which attacks red blood cells by feeding on hemoglobin and transforming it into hemozoin. Despite the WHO recommendation of prompt malaria diagnosis, the quality of microscopy‐based diagnosis is frequently inadequate while rapid diagnostic tests based on antigens are not quantitative and still affected by non‐negligible false negative/positive results. PCR‐based methods are highly performant but still not widely used in endemic areas. Here, a diagnostic tool (TMek), based on the paramagnetic properties of hemozoin nanocrystals in infected red blood cells (i‐RBCs), is reported on. Exploiting the competition between gravity and magnetic forces, i‐RBCs in a whole blood specimen are sorted and electrically detected in a microchip. The amplitude and time evolution of the electrical signal allow for the quant...
IEEE Journal of Solid-State Circuits, 2020
Pseudo-resistor circuits are used to mimic large value resistors and base their success on the re... more Pseudo-resistor circuits are used to mimic large value resistors and base their success on the reduction of occupied areas with respect to physical devices of equal value. This article presents an optimized architecture of pseudo-resistor, made in standard CMOS 0.35 µm technology to bias a low-noise transimpedance amplifier for high-sensitivity applications in the frequency range 100 kHz-10 MHz. The architecture was selected after a critical review of the different topologies to implement high-value resistances with MOSFET transistors, considering their performance in terms of linearity of response, symmetric dynamic range, frequency behavior, and simplicity of realization. The resulting circuit consumes an area of 0.017 mm 2 and features a tunable resistance from 20 M to 20 G, dynamic offset reduction due to a more than linear I-V curve, and a high-frequency noise well below the one of a physical resistor of equal value. This latter aspect highlights the larger perspective of pseudo-resistors as building blocks in very low-noise applications in addition to the advantage in occupied areas they provide.
Journal of Raman Spectroscopy, 2020
We introduce a high‐sensitivity broadband stimulated Raman scattering (SRS) setup featuring wide ... more We introduce a high‐sensitivity broadband stimulated Raman scattering (SRS) setup featuring wide spectral coverage (up to 500 cm−1) and high‐frequency resolution (≈20 cm−1). The system combines a narrowband Stokes pulse, obtained by spectral filtering an Yb laser, with a broadband pump pulse generated by a home‐built optical parametric oscillator. A single‐channel lock‐in amplifier connected to a single‐pixel photodiode measures the stimulated Raman loss signal, whose spectrum is scanned rapidly using a galvanometric mirror after the sample. We use the in‐line balanced detection approach to suppress laser fluctuations and achieve close to shot‐noise‐limited sensitivity. The setup is capable of measuring accurately the SRS spectra of several solvents and of obtaining hyperspectral data cubes consisting in the broadband SRS microscopy images of polymer beads test samples as well as of the distribution of different biological substances within plant cell walls.
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Papers by Marco Sampietro