arXiv subjects

Mariano Barella

Publications and source records attributed to Mariano Barella.

6 recordsLinked to original sources

arXiv2026

Morphology-Driven optimization of Double Nanohole-based Plasmonic Optical Tweezers

Plasmonic Optical Tweezers based on Double Nanohole (DNH) structures are an emerging tool for trapping and interrogating single proteins under physiologically relevant conditions without the need for labeling or tethering. Nevertheless, their current performance is hindered by low signal-to-noise ratios for small proteins, fabrication variability, and photothermal instabilities, in part due to the required high laser power. To address these limitations, we present a comprehensive optimization of DNH parameters using parametric simulations and morphological characterization of experimentally fabricated DNHs. This approach ensures that the optimized geometries are experimentally realizable and compatible with established fabrication processes. We evaluate critical structural features, including gap width, gap length, cusp curvature, wedged tapers, adhesion layer and gold layer thicknesses, and the inclusion of pillars inside the nanoholes. By tailoring these variables, we aim to maximize the transmission variation upon trapping single nanoparticles or proteins and the local electric-field enhancement, thereby maximizing the optical force, while minimizing the required optical power. Two optimized DNH designs are proposed and simulated using a heuristic approach and a differential evolution algorithm. Both substantially outperform the reference structure and deliver 6.5- and 22-fold increases in sensitivity and 2.4- and 1.4-fold improvement in electric-field enhancement, respectively. These refinements provide a framework for developing efficient nanostructures to study single-protein dynamics with Plasmonic Optical Tweezers.

physics.bio-ph↗

arXiv2025

Total Ionizing Dose Measurements in Small Satellites in LEO using LabOSat-01

LabOSat-01 is a payload designed to perform characterization experiments on electronic devices in hostile environments. Both Commercial-Off-The-Shelf components and custom nano and micro devices were studied in the last decade with this platform. The Total Ionizing Dose (TID) received by small satellites in Low Earth Orbit was measured with LabOSat-01 using p-MOSFET COTS and the results are presented in this work. Measurements were performed on two satellite missions, each totalling 1100 days, launched three years apart. Dosimeters were integrated in different satellite positions, with different shielding, and the measured TID after 1100 days ranged from 5 Gy to 19 Gy.

physics.space-ph↗

arXiv2024

Characterization of SiPM Performance in a Small Satellite in Low Earth Orbit using LabOSat-01

In this work, the performance of SensL MicroFC-60035 SiPM devices was studied during a 1460-day mission in Low Earth Orbit (LEO) using the LabOSat-01 characterization payload. Two of these platforms, carrying two SiPMs each, were integrated into the ÑuSat-7 satellite (COSPAR-ID: 2020-003B). Analysis revealed that these SiPMs experienced an increase in dark current over time due to damage from trapped and solar proton radiation. The total ionizing dose received by the payload and the SiPMs was measured using p-MOSFET dosimeters, with a resulting value of 5 Gy, or a 1 MeV neutron equivalent fluence of $ϕ_n = 5 \cdot 10^9$ n/cm$^2$. The dark current was observed to increase up to 500 times. Parameters such as Gain and Photon Detection Efficiency remained unchanged throughout the mission. These findings align with previous performance reports involving different SiPMs irradiated with various particles and energies.

physics.ins-det↗

arXiv2021

Challenges on Optical Printing of Colloidal Nanoparticles

While colloidal chemistry provides ways to obtain a great variety of nanoparticles, with different shapes, sizes, material composition, and surface functions, their controlled deposition and combination on arbitrary positions of substrates remains a considerable challenge. Over the last ten years, optical printing arose as a versatile method to achieve this purpose for different kinds of nanoparticles. In this article we review the state of the art of optical printing of single nanoparticles, and discuss its strengths, limitations, and future perspectives, by focusing on four main challenges: printing accuracy, resolution, selectivity, and nanoparticles photostability.

cond-mat.mes-hall↗

arXiv2021

In Situ Photothermal Response of Single Gold Nanoparticles Through Hyperspectral Imaging AntiStokes Thermometry

Several fields of applications require a reliable characterization of the photothermal response and heat dissipation of nanoscopic systems, which remains a challenging task both for modeling and experimental measurements. Here, we present a new implementation of anti-Stokes thermometry that enables the in situ photothermal characterization of individual nanoparticles (NPs) from a single hyperspectral photoluminescence confocal image. The method is label-free, applicable to any NP with detectable anti-Stokes emission, and does not require any prior information about the NP itself or the surrounding media. With it, we first studied the photothermal response of spherical gold NPs of different sizes on glass substrates, immersed in water, and found that heat dissipation is mainly dominated by the water for NPs larger than 50 nm. Then, the role of the substrate was studied by comparing the photothermal response of 80 nm gold NPs on glass with sapphire and graphene, two materials with high thermal conductivity. For a given irradiance level, the NPs reach temperatures 18% lower on sapphire and 24% higher on graphene than on bare glass. The fact that the presence of a highly conductive material such as graphene leads to a poorer thermal dissipation demonstrates that interfacial thermal resistances play a very significant role in nanoscopic systems, and emphasize the need for in situ experimental thermometry techniques. The developed method will allow addressing several open questions about the role of temperature in plasmon-assisted applications, especially ones where NPs of arbitrary shapes are present in complex matrixes and environments.

physics.optics↗

arXiv2020

COTS MOS Dosimetry on the MeMOSat Board, Results After 2.5 Years in Orbit

We present the results after 2.5 years in or-bit of Total Ionizing Dose (TID) measurements done using Metal Oxide Semiconductor (MOS) dosimeters on the MeMOSat board. The MeMOSat board was launched on July 19th 2014 at the BugSat-1 "Tita" microsatellite developed by Satellogic to stay at LEO. We used as dosimeters p-channel Commercial Off The Shelf (COTS) MOS transistors with gate oxides of 250~nm. Before launch, a subset of transistors with similar drain current to voltage (I-V)curves where selected from a group of 100 devices. The temperature dependence of the (I-V) curves was studied to find the minimum temperature coefficient biasing point. Then, a calibration subgroup of sensors was irradiated using a $^{60}$Co gamma source to study their response to TID, showing responsivities of $\sim$75~mV/krad when the sensors are irradiated without gate bias. Also, the post irradiation response of the sensors was monitored, in order to include a correction for low dose rate irradiations, yielding 30~mV/krad. A biasing and reading circuit was developed in order to allow the reading of up to 4 sensors.The threshold voltage was monitored during different periods of the mission. After 2.5 years in orbit,the threshold voltage of the sensor mounted on the MeMOSat Board had a V$_\mathrm{T}$ shift of approximately 35~mV corresponds to a dose of 1.2~krads.

physics.ins-det↗